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PLL Frequency Synthesizer ADF4108
FEATURES
8.0 GHz bandwidth 3.2 V to 3.6 V power supply Separate charge pump supply (VP) allows extended tuning voltage in 3.3 V systems Programmable, dual modulus prescaler 8/9, 16/17, 32/33, or 64/65 Programmable charge pump currents Programmable antibacklash pulse width 3-wire serial interface Analog and digital lock detect Hardware and software power-down mode Loop filter design possible with ADIsimPLL
GENERAL DESCRIPTION
The ADF4108 frequency synthesizer can be used to implement local oscillators in the up-conversion and down-conversion sections of wireless receivers and transmitters. It consists of a low noise digital PFD (phase frequency detector), a precision charge pump, a programmable reference divider, programmable A and B counters, and a dual-modulus prescaler (P/P + 1). The A (6-bit) and B (13-bit) counters, in conjunction with the dualmodulus prescaler (P/P + 1), implement an N divider (N = BP + A). In addition, the 14-bit reference counter (R counter), allows selectable REFIN frequencies at the PFD input. A complete phase-locked loop (PLL) can be implemented if the synthesizer is used with an external loop filter and voltage controlled oscillator (VCO). Its very high bandwidth means that frequency doublers can be eliminated in many high frequency systems, simplifying system architecture and reducing cost.
APPLICATIONS
Broadband wireless access Satellite systems Instrumentation Wireless LANs Base stations for wireless radio
AVDD DVDD
FUNCTIONAL BLOCK DIAGRAM
VP CPGND REFERENCE REFIN 14-BIT R COUNTER 14 R COUNTER LATCH CLK DATA LE 24-BIT INPUT REGISTER FUNCTION LATCH A, B COUNTER LATCH 13 13-BIT B COUNTER LOAD LOAD 6-BIT A COUNTER M3 M2 M1 SDOUT LOCK DETECT CURRENT SETTING 1 CPI3 CPI2 CPI1 CURRENT SETTING 2 CPI6 CPI5 CPI4 HIGH Z 19 AVDD MUX MUXOUT PHASE FREQUENCY DETECTOR RSET
CHARGE PUMP
CP
22
FROM SDOUT FUNCTION LATCH
N = BP + A
RFINA RFINB
PRESCALER P/P + 1
ADF4108
06015-001
6 CE AGND DGND
Figure 1.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2006 Analog Devices, Inc. All rights reserved.
ADF4108 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Timing Characteristics..................................................................... 5 Absolute Maximum Rating ............................................................. 6 ESD Caution.................................................................................. 6 Pin Configuration and Function Descriptions............................. 7 Typical Performance Characteristics ............................................. 8 Theory of Operation ........................................................................ 9 Reference Input Stage................................................................... 9 RF Input Stage............................................................................... 9 Prescaler (P/P + 1)........................................................................ 9 A and B Counters ......................................................................... 9 R Counter ...................................................................................... 9 Phase Frequency Detector and Charge Pump...........................9 MUXOUT and Lock Detect...................................................... 10 Input Shift Register .................................................................... 10 Latch Summary........................................................................... 11 Reference Counter Latch Map.................................................. 12 AB Counter Latch Map ............................................................. 13 Function Latch Map................................................................... 14 Initialization Latch Map ............................................................ 15 Function Latch............................................................................ 16 Initialization Latch ..................................................................... 17 Power Supply Considerations................................................... 17 Interfacing ....................................................................................... 18 ADuC812 Interface .................................................................... 18 ADSP-2181 Interface ................................................................. 18 PCB Design Guidelines for Chip Scale Package......................... 19 Outline Dimensions ....................................................................... 20 Ordering Guide .......................................................................... 20
REVISION HISTORY
4/06--Revision 0: Initial Version
Rev. 0 | Page 2 of 20
ADF4108 SPECIFICATIONS
AVDD = DVDD = 3.3 V 2%, AVDD VP 5.5 V, AGND = DGND = CPGND = 0 V, RSET = 5.1 k, dBm referred to 50 , TA = TMIN to TMAX, unless otherwise noted. Table 1.
Parameter RF CHARACTERISTICS RF Input Frequency (RFIN) RF Input Sensitivity Maximum Allowable Prescaler Output Frequency 3 REFIN CHARACTERISTICS REFIN Input Frequency REFIN Input Sensitivity 4 REFIN Input Capacitance REFIN Input Current PHASE DETECTOR Phase Detector Frequency 6 CHARGE PUMP ICP Sink/Source High Value Low Value Absolute Accuracy RSET Range ICP Three-State Leakage Sink and Source Current Matching ICP vs. VCP ICP vs. Temperature LOGIC INPUTS VIH, Input High Voltage VIL, Input Low Voltage IINH, IINL, Input Current CIN, Input Capacitance LOGIC OUTPUTS VOH, Output High Voltage VOH, Output High Voltage IOH VOL, Output Low Voltage POWER SUPPLIES AVDD DVDD VP IDD (AIDD + DIDD) 7 IP Power-Down Mode (AIDD + DIDD) 8 B Version 1 1.0/8.0 -5/+5 300 325 20/250 0.8/VDD 10 100 104 B Chips 2 (Typ) 1.0/8.0 -5/+5 300 325 20/250 0.8/VDD 10 100 104 Unit GHz min/max dBm min/max MHz max MHz max MHz min/max V p-p min/max pF max A max MHz max Programmable; see Figure 19 5 625 2.5 3.0/11 1 2 1.5 2 1.4 0.6 1 10 1.4 VDD - 0.4 100 0.4 3.2/3.6 AVDD AVDD/5.5 17 0.4 10 5 625 2.5 3.0/11 1 2 1.5 2 1.4 0.6 1 10 1.4 VDD - 0.4 100 0.4 3.2/3.6 AVDD AVDD/5.5 17 0.4 10 mA typ A typ % typ k typ nA typ % typ % typ % typ V min V max A max pF max V min V min A max V max V min/V max V min/V max mA max mA max A typ AVDD VP 5.5 V 15 mA typ TA = 25C Open-drain output chosen; 1 k pull-up resistor to 1.8 V CMOS output chosen IOL = 500 A With RSET = 5.1 k With RSET = 5.1 k See Figure 19 1 nA typical; TA = 25C 0.5 V VCP VP - 0.5 V 0.5 V VCP VP - 0.5 V VCP = VP/2 Test Conditions/Comments See Figure 12 for input circuit For lower frequencies ensure slew rate (SR) > 320 V/s P=8 P = 16 For f < 20 MHz, ensure SR > 50 V/s Biased at AVDD/2 5
Rev. 0 | Page 3 of 20
ADF4108
Parameter NOISE CHARACTERISTICS Normalized Phase Noise Floor 9 Phase Noise Performance 10 7900 MHz Output 11 Spurious Signals 7900 MHz Output11
1 2
B Version 1 -219 -81 -61
B Chips 2 (Typ) -219 -81 -61
Unit dBc/Hz typ dBc/Hz typ dBc typ
Test Conditions/Comments
@ VCO output @ 1 kHz offset and 1 MHz PFD frequency @ 1 MHz offset and 1 MHz PFD frequency
Operating temperature range (B version) is -40C to +85C. The B chip specifications are given as typical values. 3 This is the maximum operating frequency of the CMOS counters. The prescaler value should be chosen to ensure that the RF input is divided down to a frequency that is less than this value. 4 AVDD = DVDD = 3.3 V. 5 AC coupling ensures AVDD/2 bias. 6 Guaranteed by design. Sample tested to ensure compliance. 7 TA = 25C; AVDD = DVDD = 3.3 V; P = 32; RFIN = 8 GHz, fPFD = 200 kHz, REFIN = 10 MHz. 8 TA = 25C; AVDD = DVDD = 3.3 V; R = 16,383; A = 63; B = 891; P = 32; RFIN = 7.0 GHz. 9 This value can be used to calculate phase noise for any application. Use the formula -219 + 10 log(fPFD) + 20 logN to calculate in-band phase noise performance as seen at the VCO output. The value given is the lowest noise mode. 10 The phase noise is measured with the EVAL-ADF4108EB1 evaluation board, with the Hittite HMC506LP4 VCO. The spectrum analyzer provides the REFIN for the synthesizer (fREFOUT = 10 MHz @ 0 dBm). 11 fREFIN = 10 MHz; fPFD = 1 MHz; fRF = 7900 MHz; N = 7900; loop B/W = 50 kHz, VCO = HMC506LP4, spurs are dominated by the leakage current on the tuning port of the HMC506LP4 VCO.
Rev. 0 | Page 4 of 20
ADF4108 TIMING CHARACTERISTICS
AVDD = DVDD = 3.3 V 2%, AVDD VP 5.5 V, AGND = DGND = CPGND = 0 V, RSET = 5.1 k, dBm referred to 50 , TA = TMIN to TMAX, unless otherwise noted. Table 2.
Parameter 1 t1 t2 t3 t4 t5 t6
1 2
Limit 2 (B Version) 10 10 25 25 10 20
Unit ns min ns min ns min ns min ns min ns min
Test Conditions/Comments DATA to CLOCK setup time DATA to CLOCK hold time CLOCK high duration CLOCK low duration CLOCK to LE setup time LE pulse width
Guaranteed by design but not production tested. Operating temperature range (B Version) is -40C to +85C.
t3
CLOCK
t4
t1
DATA DB23 (MSB) DB22
t2
DB2 DB1 (CONTROL BIT C2) DB0 (LSB) (CONTROL BIT C1)
t6
LE
t5
LE
06015-002
Figure 2. Timing Diagram
Rev. 0 | Page 5 of 20
ADF4108 ABSOLUTE MAXIMUM RATING
TA = 25C, unless otherwise noted. Table 3.
Parameter AVDD to GND 1 AVDD to DVDD VP to GND VP to AVDD Digital I/O Voltage to GND Analog I/O Voltage to GND REFIN, RFINA, RFINB to GND Operating Temperature Range Industrial (B Version) Storage Temperature Range Maximum Junction Temperature TSSOP JA Thermal Impedance CSP JA Thermal Impedance (Paddle Soldered) Reflow Soldering Peak Temperature (60 sec) Time at Peak Temperature Transistor Count CMOS Bipolar
1
Rating -0.3 V to +3.9 V -0.3 V to +0.3 V -0.3 V to +5.8 V -0.3 V to +5.8 V -0.3 V to VDD + 0.3 V -0.3 V to VP + 0.3 V -0.3 V to VDD + 0.3 V -40C to +85C -65C to +125C 150C 112C/W 30.4C/W
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. This device is a high performance RF integrated circuit with an ESD rating of <2 kV, and it is ESD sensitive. Proper precautions should be taken for handling and assembly.
260 40 sec 6425 303
GND = AGND = DGND = 0 V.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Rev. 0 | Page 6 of 20
ADF4108 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
RSET 1 CP 2 CPGND 3 AGND 4
16 VP 15 DVDD
ADF4108
14 MUXOUT
20 CP 19 RSET 18 VP 17 DVDD 16 DVDD
CPGND 1 AGND 2 AGND 3 RFINB 4 RFINA 5
PIN 1 INDICATOR
TOP VIEW 13 LE (Not to Scale) 12 DATA RFINB 5 RFINA 6 AVDD 7 REFIN 8
11 CLK 10 CE
ADF4108
TOP VIEW (Not to Scale)
15 MUXOUT 14 LE 13 DATA 12 CLK 11 CE
NOTE: TRANSISTOR COUNT 6425 (CMOS), 303 (BIPOLAR).
Figure 3. TSSOP Pin Configuration for TSSOP
06015-030
Figure 4. LFCSP_VQ Pin Configuration
Table 4. Pin Function Descriptions
Pin No. TSSOP LFCSP_VQ 1 19 Mnemonic RSET Description Connecting a resistor between this pin and CPGND sets the maximum charge pump output current. The nominal voltage potential at the RSET pin is 0.66 V. The relationship between ICP and RSET is 25.5 I CP MAX = R SET with RSET = 5.1 k, ICP MAX = 5 mA. Charge Pump Output. When enabled, this pin provides ICP to the external loop filter, which in turn drives the external VCO. Charge Pump Ground. This is the ground return path for the charge pump. Analog Ground. This is the ground return path of the prescaler. Complementary Input to the RF Prescaler. This point must be decoupled to the ground plane with a small bypass capacitor, typically 100 pF. See Figure 12. Input to the RF Prescaler. This small signal input is ac-coupled to the external VCO. Analog Power Supply. This voltage may range from 3.2 V to 3.6 V. Decoupling capacitors to the analog ground plane should be placed as close as possible to this pin. AVDD must be the same value as DVDD. Reference Input. This is a CMOS input with a nominal threshold of VDD/2 and a dc equivalent input resistance of 100 k. See Figure 11. This input can be driven from a TTL or CMOS crystal oscillator or it can be ac-coupled. Digital Ground. Chip Enable. A logic low on this pin powers down the device and puts the charge pump output into three-state mode. Taking the pin high will power up the device, depending on the status of the power-down bit, F2. Serial Clock Input. This serial clock is used to clock in the serial data to the registers. The data is latched into the 24-bit shift register on the CLK rising edge. This input is a high impedance CMOS input. Serial Data Input. The serial data is loaded MSB first with the 2 LSBs being the control bits. This input is a high impedance CMOS input. Load Enable, CMOS Input. When LE goes high, the data stored in the shift registers is loaded into one of the four latches, the latch being selected using the control bits. This multiplexer output allows either the lock detect, the scaled RF, or the scaled reference frequency to be accessed externally. Digital Power Supply. This may range from 3.2 V to 3.6 V. Decoupling capacitors to the digital ground plane should be placed as close as possible to this pin. DVDD must be the same value as AVDD. Charge Pump Power Supply. This voltage should be greater than or equal to VDD. In systems where VDD is 3.3 V, it can be set to 5 V and used to drive a VCO with a tuning range of up to 5 V.
2 3 4 5 6 7
20 1 2, 3 4 5 6, 7
CP CPGND AGND RFINB RFINA AVDD
8
8
REFIN
9 10
9, 10 11
DGND CE
11
12
CLK
12 13 14 15 16
13 14 15 16, 17 18
DATA LE MUXOUT DVDD VP
Rev. 0 | Page 7 of 20
06015-003
9
DGND
AVDD 6 AVDD 7 REFIN 8 DGND 9 DGND 10
ADF4108 TYPICAL PERFORMANCE CHARACTERISTICS
FREQ UNIT: GHz PARAM TYPE: s DATA FORMAT: MA Freq 0.50000 0.60000 0.70000 0.80000 0.90000 1.00000 1.10000 1.20000 1.30000 1.40000 1.50000 1.60000 1.70000 1.80000 1.90000 2.00000 2.10000 2.20000 2.30000 2.40000 2.50000 2.60000 2.70000 2.80000 2.90000 3.00000 3.10000 3.20000 3.30000 3.40000 3.50000 3.60000 3.70000 3.80000 3.90000 4.00000 4.10000 4.20000 MAGS11 0.89148 0.88133 0.87152 0.85855 0.84911 0.83512 0.82374 0.80871 0.79176 0.77205 0.75696 0.74234 0.72239 0.69419 0.67288 0.66227 0.64758 0.62454 0.59466 0.55932 0.52256 0.48754 0.46411 0.45776 0.44859 0.44588 0.43810 0.43269 0.42777 0.42859 0.43365 0.43849 0.44475 0.44800 0.45223 0.45555 0.45313 0.45622 KEYWORD: R ANGS11 -17.2820 -20.6919 -24.5386 -27.3228 -31.0698 -34.8623 -38.5574 -41.9093 -45.6990 -49.4185 -52.8898 -56.2923 -60.2584 -63.1446 -65.6464 -68.0742 -71.3530 -75.5658 -79.6404 -82.8246 -85.2795 -85.6298 -86.1854 -86.4997 -88.8080 -91.9737 -95.4087 -99.1282 -102.748 -107.167 -111.883 -117.548 -123.856 -130.399 -136.744 -142.766 -149.269 -154.884 Freq 4.30000 4.40000 4.50000 4.60000 4.70000 4.80000 4.90000 5.00000 5.10000 5.20000 5.30000 5.40000 5.50000 5.60000 5.70000 5.80000 5.90000 6.00000 6.10000 6.20000 6.30000 6.40000 6.50000 6.60000 6.70000 6.80000 6.90000 7.00000 7.10000 7.20000 7.30000 7.40000 7.50000 7.60000 7.70000 7.80000 7.90000 8.00000 MAGS11 0.45555 0.46108 0.45325 0.45054 0.45200 0.45043 0.45282 0.44287 0.44909 0.44294 0.44558 0.45417 0.46038 0.47128 0.47439 0.48604 0.50637 0.52172 0.53342 0.53716 0.55804 0.56362 0.58268 0.59248 0.61066 0.61830 0.61633 0.61673 0.60597 0.58376 0.57673 0.58157 0.60040 0.61332 0.62927 0.63938 0.65320 0.65804 ANGS11 -159.680 -164.916 -168.452 -173.462 -176.697 178.824 174.947 170.237 166.617 162.786 158.766 153.195 147.721 139.760 132.657 125.782 121.110 115.400 107.705 101.572 97.5379 93.0936 89.2227 86.3300 83.0956 80.8843 78.0872 75.3727 73.9456 73.5883 74.1975 76.2136 77.1545 76.1122 74.8359 74.0546 72.0061 69.9926
OUTPUT POWER (dB)
VDD = 3.3V, VP = 5V ICP = 5mA PFD FREQUENCY = 1MHz -20 LOOP BANDWIDTH = 50kHz RES BANDWIDTH = 3kHz VIDEO BANDWIDTH = 3kHz -40 AVERAGES = 1 OUTPUT POWER = -0.3dBm HMC506LP4 VCO -60
0
-0.3dBm
-61dBc
-80
-100
06015-004
-2MHz
-1MHz
7900MHz FREQUENCY
1MHz
2MHz
Figure 5. S Parameter Data for the RF Input
Figure 8. Reference Spurs at 7.9 GHz Note: The spurs are dominated by the leakage current of the tuning port on the HMC506LP4 VCO. The leakage current was measured to be 27 nA.
6
0 VDD = 3.3V -5 TA = +85C
RF INPUT POWER (dBm)
5 4 3 2
ICP (mA)
VPP = 5V ICP SETTLING = 5mA
-10 -15 TA = +25C -20 -25 -30 TA = -40C
06015-005
1 0 -1 -2 -3 -4 -5
1
2
3
4
5
6
7
8
9
0
0.5
1.0
1.5
2.0
2.5 VCP (V)
3.0
3.5
4.0
4.5
5.0
RF INPUT FREQUENCY (GHz)
Figure 6. RF Input Sensitivity
Figure 9. Charge Pump Output Characteristics
-50 -60 -70
-120 VDD = 3V VP = 5V -130
PHASE NOISE (dBc/Hz)
-80 -90 -100 -110 -120 -130 -140 VDD = 3.3V, VP = 5V ICP = 5mA PFD FREQUENCY = 1MHz LOOP BANDWIDTH = 50kHz PHASE NOISE = -82dBc/Hz @ 1kHz HMC506LP4 VCO
06015-010
PHASE NOISE (dBc/Hz)
-140
-150
-160
-170
10MHz FREQUENCY OFFSET
100k
1M
10M
100M
PHASE FREQUENCY DETECTOR (Hz)
Figure 7. Phase Noise at 7.9 GHz Phase Noise
Figure 10. Phase Noise (Referred to CP Output) vs. PFD Frequency
Rev. 0 | Page 8 of 20
06015-014
-150 1kHz
-180 10k
06015-015
-35
-6
06015-011
-120
ADF4108 THEORY OF OPERATION
REFERENCE INPUT STAGE
The reference input stage is shown in Figure 11. SW1 and SW2 are normally closed switches. SW3 is normally open. When power-down is initiated, SW3 is closed and SW1 and SW2 are opened. This ensures that there is no loading of the REFIN pin on power-down.
POWER-DOWN CONTROL
feedback counter. The counters are specified to work when the prescaler output is 300 MHz or less. Thus, with an RF input frequency of 4.0 GHz, a prescaler value of 16/17 is valid but a value of 8/9 is not valid.
Pulse Swallow Function
The A and B counters, in conjunction with the dual-modulus prescaler, make it possible to generate output frequencies that are spaced only by the reference frequency divided by R. The equation for the VCO frequency is as follows:
f VCO = [(P x B ) + A ] x f REFIN R
NC SW2 REFIN NC SW1
100k
TO R COUNTER BUFFER
where: fVCO is the output frequency of external voltage controlled oscillator (VCO). P is the preset modulus of dual-modulus prescaler (8/9, 16/17, and so on.). B is the preset divide ratio of binary 13-bit counter (3 to 8191). A is the preset divide ratio of binary 6-bit swallow counter (0 to 63). fREFIN is the external reference frequency oscillator.
N = BP + A
06015-016
SW3 NO
Figure 11. Reference Input Stage
RF INPUT STAGE
The RF input stage is shown in Figure 12. It is followed by a 2-stage limiting amplifier to generate the CML clock levels needed for the prescaler.
BIAS GENERATOR 500 1.6V AVDD 500
13-BIT B COUNTER FROM RF INPUT STAGE PRESCALER P/P + 1 MODULUS CONTROL N DIVIDER LOAD LOAD 6-BIT A COUNTER
TO PFD
RFINA
RFINB
Figure 13. A and B Counters
06015-017
AGND
R COUNTER
The 14-bit R counter allows the input reference frequency to be divided down to produce the reference clock to the phase frequency detector (PFD). Division ratios from 1 to 16,383 are allowed.
Figure 12. RF Input Stage
PRESCALER (P/P + 1)
The dual-modulus prescaler (P/P + 1), along with the A and B counters, enables the large division ratio, N, to be realized (N = BP + A). The dual-modulus prescaler, operating at CML levels, takes the clock from the RF input stage and divides it down to a manageable frequency for the CMOS A and B counters. The prescaler is programmable. It can be set in software to 8/9, 16/17, 32/33, or 64/65. It is based on a synchronous 4/5 core. A minimum divide ratio is possible for contiguous output frequencies. This minimum is determined by P, the prescaler value, and is given by: (P2 - P).
PHASE FREQUENCY DETECTOR AND CHARGE PUMP
The phase frequency detector (PFD) takes inputs from the R counter and N counter (N = BP + A) and produces an output proportional to the phase and frequency difference between them. Figure 14 is a simplified schematic. The PFD includes a programmable delay element that controls the width of the antibacklash pulse. This pulse ensures that there is no dead zone in the PFD transfer function and minimizes phase noise and reference spurs. Two bits in the reference counter latch, ABP2 and ABP1, control the width of the pulse. (See Figure 17.)
A AND B COUNTERS
The A and B CMOS counters combine with the dual-modulus prescaler to allow a wide ranging division ratio in the PLL
Rev. 0 | Page 9 of 20
06015-018
ADF4108
VP CHARGE PUMP
DVDD
HI
D1
Q1 U1
UP
ANALOG LOCK DETECT DIGITAL LOCK DETECT R COUNTER OUTPUT MUX CONTROL
R DIVIDER
CLR1
PROGRAMMABLE DELAY ABP2 ABP1
MUXOUT
U3 CP
N COUNTER OUTPUT SDOUT
HI
CLR2 DOWN D2 Q2
06015-019
DGND
Figure 15. MUXOUT Circuit
CPGND
U2 N DIVIDER
INPUT SHIFT REGISTER
The ADF4108 digital section includes a 24-bit input shift register, a 14-bit R counter, and a 19-bit N counter, comprising a 6-bit A counter and a 13-bit B counter. Data is clocked into the 24-bit shift register on each rising edge of CLK. The data is clocked in MSB first. Data is transferred from the shift register to one of four latches on the rising edge of LE. The destination latch is determined by the state of the two control bits (C2, C1) in the shift register. These are the 2 LSBs, DB1 and DB0, as shown in the timing diagram of Figure 2. The truth table for these bits is shown in Table 5. Figure 16 shows a summary of how the latches are programmed. Table 5. C2 and C1 Truth Table
Control Bits C2 C1 0 0 0 1 1 0 1 1 Data Latch R counter N counter (A and B) Function latch (Including prescaler) Initialization latch
Figure 14. PFD Simplified Schematic and Timing (in Lock)
MUXOUT AND LOCK DETECT
The output multiplexer on the ADF4108 allows the user to access various internal points on the chip. The state of MUXOUT is controlled by M3, M2, and M1 in the function latch. Figure 19 shows the full truth table. Figure 15 shows the MUXOUT section in block diagram form.
Lock Detect
MUXOUT can be programmed for two types of lock detect: digital lock detect and analog lock detect. Digital lock detect is active high. When the lock detect precision (LDP) bit in the R counter latch is set to 0, digital lock detect is set high when the phase error on three consecutive phase detector (PD) cycles is less than 15 ns. With LDP set to 1, five consecutive cycles of less than 15 ns are required to set the lock detect. It will stay set high until a phase error of greater than 25 ns is detected on any subsequent PD cycle. The N-channel open-drain analog lock detect should be operated with an external pull-up resistor of 10 k nominal. When lock has been detected, this output will be high with narrow, low-going pulses.
Rev. 0 | Page 10 of 20
06015-020
ADF4108
LATCH SUMMARY
REFERENCE COUNTER LATCH
LOCK DETECT PRECISION
RESERVED
TEST MODE BITS
ANTIBACKLASH WIDTH
14-BIT REFERENCE COUNTER
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 X 0 0 LDP T2 T1 ABP2 ABP1 R14 R13 R12 R11 R10 R9
DB9 R8
DB8 R7
DB7 R6
DB6 R5
DB5 R4
DB4 R3
DB3 R2
DB2 R1
DB1 C2 (0)
DB0 C1 (0)
N COUNTER LATCH
CP GAIN
RESERVED
13-BIT B COUNTER
6-BIT A COUNTER
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 X X G1 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3
DB9 B2
DB8 B1
DB7 A6
DB6 A5
DB5 A4
DB4 A3
DB3 A2
DB2 A1
DB1
DB0
C2 (0) C1 (1)
FUNCTION LATCH
FASTLOCK ENABLE
FASTLOCK MODE
CP THREESTATE
PD POLARITY
PRESCALER VALUE
CURRENT SETTING 2
COUNTER RESET
POWERDOWN 2
POWERDOWN 1
CURRENT SETTING 1
TIMER COUNTER CONTROL
MUXOUT CONTROL
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 P2 P1 PD2 CPI6 CPI5 CPI4 CPI3 CPI2 CPI1 TC4 TC3 TC2 TC1 F5
DB9 F4
DB8 F3
DB7 F2
DB6 M3
DB5 M2
DB4 M1
DB3 PD1
DB2 F1
DB1
DB0
C2 (1) C1 (0)
INITIALIZATION LATCH
FASTLOCK MODE FASTLOCK ENABLE
CP THREESTATE
PD POLARITY
PRESCALER VALUE
CURRENT SETTING 2
CURRENT SETTING 1
COUNTER RESET
POWERDOWN 2
POWERDOWN 1
TIMER COUNTER CONTROL
MUXOUT CONTROL
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 P2 P1 PD2 CPI6 CPI5 CPI4 CPI3 CPI2 CPI1 TC4 TC3 TC2 TC1 F5
DB9 F4
DB8
F3
DB7 F2
DB6 M3
DB5 M2
DB4 M1
DB3 PD1
DB2 F1
DB1
DB0
06015-021
C2 (1) C1 (1)
Figure 16. Latch Summary
Rev. 0 | Page 11 of 20
ADF4108
REFERENCE COUNTER LATCH MAP
LOCK DETECT PRECISION
RESERVED
TEST MODE BITS
ANTIBACKLASH WIDTH
14-BIT REFERENCE COUNTER
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 X 0 0 LDP T2 T1 ABP2 ABP1 R14 R13 R12 R11 R10 R9
DB9 R8
DB8 R7
DB7 R6
DB6 R5
DB5 R4
DB4 R3
DB3 R2
DB2 R1
DB1 C2 (0)
DB0 C1 (0)
X = DON'T CARE
R14 0 0 0 0 . . . 1 1 1 1 R13 0 0 0 0 . . . 1 1 1 1 R12 0 0 0 0 . . . 1 1 1 1 .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... R3 0 0 0 1 . . . 1 1 1 1 R2 0 1 1 0 . . . 0 0 1 1 R1 1 0 1 0 . . . 0 1 0 1 DIVIDE RATIO 1 2 3 4 . . . 16380 16381 16382 16383
ABP2 0 0 1 1
ABP1 0 1 0 1
ANTIBACKLASH PULSE WIDTH 2.9ns 1.3ns 6.0ns 2.9ns
TEST MODE BITS SHOULD BE SET TO 00 FOR NORMAL OPERATION.
LDP 0 1
OPERATION THREE CONSECUTIVE CYCLES OF PHASE DELAY LESS THAN 15ns MUST OCCUR BEFORE LOCK DETECT IS SET. FIVE CONSECUTIVE CYCLES OF PHASE DELAY LESS THAN 15ns MUST OCCUR BEFORE LOCK DETECT IS SET.
Figure 17. Reference Counter Latch Map
Rev. 0 | Page 12 of 20
06015-022
BOTH OF THESE BITS MUST BE SET TO 0 FOR NORMAL OPERATION.
ADF4108
AB COUNTER LATCH MAP
CP GAIN
RESERVED 13-BIT B COUNTER 6-BIT A COUNTER CONTROL BITS
DB23 X
DB22 X
DB21 G1
DB20 B13
DB19 B12
DB18 B11
DB17 B10
DB16 B9
DB15 B8
DB14 B7
DB13 B6
DB12 B5
DB11 B4
DB10 B3
DB9 B2
DB8 B1
DB7 A6
DB6 A5
DB5 A4
DB4 A3
DB3 A2
DB2 A1
DB1
DB0
C2 (0) C1 (1)
X = DON'T CARE
A6 0 0 0 0 . . . 1 1 1 1
A5 0 0 0 0 . . . 1 1 1 1
.......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... ..........
A2 0 0 1 1 . . . 0 0 1 1
A1 0 1 0 1 . . . 0 1 0 1
A COUNTER DIVIDE RATIO 0 1 2 3 . . . 60 61 62 63
B13 0 0 0 0 . . . 1 1 1 1
B12 0 0 0 0 . . . 1 1 1 1
B11 0 0 0 0 . . . 1 1 1 1 .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... ..........
B3 0 0 0 0 . . . 1 1 1 1
B2 0 0 1 1 . . . 0 0 1 1
B1 0 1 0 1 . . . 0 1 0 1
B COUNTER DIVIDE RATIO NOT ALLOWED NOT ALLOWED NOT ALLOWED 3 . . . 8188 8189 8190 8191
F4 (FUNCTION LATCH) FASTLOCK ENABLE 0 0 1 1
G1 CP GAIN 0 1 0 1
OPERATION CHARGE PUMP CURRENT SETTING 1 IS PERMANENTLY USED. CHARGE PUMP CURRENT SETTING 2 IS PERMANENTLY USED. CHARGE PUMP CURRENT SETTING 1 IS USED. CHARGE PUMP CURRENT IS SWITCHED TO SETTING 2. THE TIME SPENT IN SETTING 2 IS DEPENDENT ON WHICH FASTLOCK MODE IS USED. SEE FUNCTION LATCH DESCRIPTION.
N = BP + A, P IS PRESCALER VALUE SET IN THE FUNCTION LATCH. B MUST BE GREATER THAN OR EQUAL TO A. FOR CONTINUOUSLY ADJACENT VALUES OF (N x FREF ), AT THE OUTPUT, NMIN IS (P2 - P).
06015-023
THESE BITS ARE NOT USED BY THE DEVICE AND ARE DON'T CARE BITS.
Figure 18. AB Counter Latch Map
Rev. 0 | Page 13 of 20
ADF4108
FUNCTION LATCH MAP
FASTLOCK MODE FASTLOCK ENABLE CP THREESTATE PD POLARITY
PRESCALER VALUE CURRENT SETTING 2 CURRENT SETTING 1
COUNTER RESET
DB2 F1
POWERDOWN 1
POWERDOWN 2
TIMER COUNTER CONTROL
MUXOUT CONTROL
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 P2 P1 PD2 CPI6 CPI5 CPI4 CPI3 CPI2 CPI1 TC4 TC3 TC2 TC1 F5
DB9 F4
DB8 F3
DB7 F2
DB6 M3
DB5 M2
DB4 M1
DB3 PD1
DB1
DB0
C2 (1) C1 (0)
F2 0 1
PHASE DETECTOR POLARITY NEGATIVE POSITIVE
F1 0 1
COUNTER OPERATION NORMAL R, A, B COUNTERS HELD IN RESET
F3 0 1
CHARGE PUMP OUTPUT NORMAL THREE-STATE
F4 0 1 1
F5 X 0 1
FASTLOCK MODE FASTLOCK DISABLED FASTLOCK MODE 1 FASTLOCK MODE 2
TC4 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
TC3 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
TC2 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
TC1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
TIMEOUT (PFD CYCLES) 3 7 11 15 19 23 27 31 35 39 43 47 51 55 59 63
M3 0 0 0 0 1 1 1 1
M2 0 0 1 1 0 0 1 1
M1 0 1 0 1 0 1 0 1
OUTPUT THREE-STATE OUTPUT DIGITAL LOCK DETECT (ACTIVE HIGH) N DIVIDER OUTPUT DVDD R DIVIDER OUTPUT N-CHANNEL OPEN-DRAIN LOCK DETECT SERIAL DATA OUTPUT DGND
CPI6 CPI3 0 0 0 0 1 1 1 1
CPI5 CPI2 0 0 1 1 0 0 1 1
CPI4 CPI1 0 1 0 1 0 1 0 1 3k 1.06 2.12 3.18 4.24 5.30 6.36 7.42 8.50
ICP (mA) 5.1k 0.625 1.25 1.875 2.5 3.125 3.75 4.375 5.0 11k 0.289 0.580 0.870 1.160 1.450 1.730 2.020 2.320
CE PIN 0 1 1 1 P2 0 0 1 1 P1 0 1 0 1
PD2 X X 0 1
PD1 X 0 1 1
MODE ASYNCHRONOUS POWER-DOWN NORMAL OPERATION ASYNCHRONOUS POWER-DOWN SYNCHRONOUS POWER-DOWN
PRESCALER VALUE
06015-024
8/9 16/17 32/33 64/65
Figure 19. Function Latch Map
Rev. 0 | Page 14 of 20
ADF4108
INITIALIZATION LATCH MAP
FASTLOCK MODE FASTLOCK ENABLE CP THREESTATE PD POLARITY
PRESCALER VALUE CURRENT SETTING 2 CURRENT SETTING 1
COUNTER RESET
DB2 F1
POWERDOWN 1
POWERDOWN 2
TIMER COUNTER CONTROL
MUXOUT CONTROL
CONTROL BITS
DB23 DB22 DB21 DB20 DB19 DB18 DB17 DB16 DB15 DB14 DB13 DB12 DB11 DB10 P2 P1 PD2 CPI6 CPI5 CPI4 CPI3 CPI2 CPI1 TC4 TC3 TC2 TC1 F5
DB9 F4
DB8 F3
DB7 F2
DB6 M3
DB5 M2
DB4 M1
DB3 PD1
DB1
DB0
C2 (1) C1 (1)
F2 0 1
PHASE DETECTOR POLARITY NEGATIVE POSITIVE
F1 0 1
COUNTER OPERATION NORMAL R, A, B COUNTERS HELD IN RESET
F3 0 1
CHARGE PUMP OUTPUT NORMAL THREE-STATE
F4 0 1 1
F5 X 0 1
FASTLOCK MODE FASTLOCK DISABLED FASTLOCK MODE 1 FASTLOCK MODE 2
TC4 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1
TC3 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1
TC2 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1
TC1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
TIMEOUT (PFD CYCLES) 3 7 11 15 19 23 27 31 35 39 43 47 51 55 59 63
M3 0 0 0 0 1 1 1 1
M2 0 0 1 1 0 0 1 1
M1 0 1 0 1 0 1 0 1
OUTPUT THREE-STATE OUTPUT DIGITAL LOCK DETECT (ACTIVE HIGH) N DIVIDER OUTPUT DVDD R DIVIDER OUTPUT N-CHANNEL OPEN-DRAIN LOCK DETECT SERIAL DATA OUTPUT DGND
CPI6 CPI3 0 0 0 0 1 1 1 1
CPI5 CPI2 0 0 1 1 0 0 1 1
CPI4 CPI1 0 1 0 1 0 1 0 1 3k 1.06 2.12 3.18 4.24 5.30 6.36 7.42 8.50
ICP (mA) 5.1k 0.625 1.25 1.875 2.5 3.125 3.75 4.375 5.0 11k 0.289 0.580 0.870 1.160 1.450 1.730 2.020 2.320
CE PIN 0 1 1 1 P2 0 0 1 1 P1 0 1 0 1
PD2 X X 0 1
PD1 X 0 1 1
MODE ASYNCHRONOUS POWER-DOWN NORMAL OPERATION ASYNCHRONOUS POWER-DOWN SYNCHRONOUS POWER-DOWN
PRESCALER VALUE
06015-025
8/9 16/17 32/33 64/65
Figure 20. Initialization Latch Map
Rev. 0 | Page 15 of 20
ADF4108
FUNCTION LATCH
The on-chip function latch is programmed with C2 and C1 set to 1 and 0, respectively. Figure 19 shows the input data format for programming the function latch. fastlock is enabled, this bit determines which fastlock mode is used. If the fastlock mode bit is 0, then Fastlock Mode 1 is selected; and if the fastlock mode bit is 1, then Fastlock Mode 2 is selected.
Counter Reset
DB2 (F1) is the counter reset bit. When this bit is 1, the R counter and the AB counters are reset. For normal operation, this bit should be 0. Upon powering up, the F1 bit needs to be disabled (set to 0). Then, the N counter resumes counting in close alignment with the R counter. (The maximum error is one prescaler cycle.)
Fastlock Mode 1
The charge pump current is switched to the contents of Current Setting 2. The device enters fastlock by having a 1 written to the CP gain bit in the AB counter latch. The device exits fastlock by having a 0 written to the CP gain bit in the AB counter latch.
Fastlock Mode 2
The charge pump current is switched to the contents of Current Setting 2. The device enters fastlock by having a 1 written to the CP gain bit in the AB counter latch. The device exits fastlock under the control of the timer counter. After the timeout period determined by the value in TC4:TC1, the CP gain bit in the AB counter latch is automatically reset to 0 and the device reverts to normal mode instead of fastlock. See Figure 19 for the timeout periods.
Power-Down
DB3 (PD1) and DB21 (PD2) provide programmable powerdown modes. They are enabled by the CE pin. When the CE pin is low, the device is immediately disabled regardless of the states of PD2 and PD1. In the programmed asynchronous power-down, the device powers down immediately after latching a 1 into the PD1 bit, with the condition that PD2 has been loaded with a 0. In the programmed synchronous power-down, the device power-down is gated by the charge pump to prevent unwanted frequency jumps. Once the power-down is enabled by writing a 1 into PD1 (on condition that a 1 has also been loaded to PD2), then the device will go into power-down on the occurrence of the next charge pump event. When a power-down is activated (either synchronous or asynchronous mode, including CE pin activated power-down), the following events occur: * * * * * * * All active dc current paths are removed. The R, N, and timeout counters are forced to their load state conditions. The charge pump is forced into three-state mode. The digital lock detect circuitry is reset. The RFIN input is debiased. The reference input buffer circuitry is disabled. The input register remains active and capable of loading and latching data.
Timer Counter Control
The user has the option of programming two charge pump currents. The intent is that Current Setting 1 is used when the RF output is stable and the system is in a static state. Current Setting 2 is meant to be used when the system is dynamic and in a state of change (that is, when a new output frequency is programmed). The normal sequence of events is as follows: The user initially decides what the preferred charge pump currents are going to be. For example, the choice may be 2.5 mA as Current Setting 1 and 5 mA as Current Setting 2. At the same time it must be decided how long the secondary current is to stay active before reverting to the primary current. This is controlled by the timer counter control bits, DB14:DB11 (TC4:TC1) in the function latch. The truth table is given in Figure 19. Now, to program a new output frequency, the user simply programs the AB counter latch with new values for A and B. At the same time, the CP gain bit can be set to 1, which sets the charge pump with the value in CPI6:CPI4 for a period of time determined by TC4-TC1. When this time is up, the charge pump current reverts to the value set by CPI3:CPI1. At the same time, the CP gain bit in the AB counter latch is reset to 0 and is now ready for the next time the user wishes to change the frequency. Note that there is an enable feature on the timer counter. It is enabled when Fastlock Mode 2 is chosen by setting the fastlock mode bit (DB10) in the function latch to 1.
MUXOUT Control
The on-chip multiplexer is controlled by M3, M2, and M1 on the ADF4108. Figure 19 shows the truth table.
Fastlock Enable Bit
DB9 of the function latch is the fastlock enable bit. Fastlock is enabled only when this bit is 1.
Fastlock Mode Bit
DB10 of the function latch is the fastlock mode bit. When
Rev. 0 | Page 16 of 20
ADF4108
Charge Pump Currents
CPI3, CPI2, and CPI1 program Current Setting 1 for the charge pump. CPI6, CPI5, and CPI4 program Current Setting 2 for the charge pump. The truth table is given in Figure 19. When the initialization latch is loaded, the following occurs:
* * The function latch contents are loaded. An internal pulse resets the R, AB, and timeout counters to load-state conditions and also three-states the charge pump. Note that the prescaler band gap reference and the oscillator input buffer are unaffected by the internal reset pulse, allowing close phase alignment when counting resumes. Latching the first AB counter data after the initialization word will activate the same internal reset pulse. Successive AB loads will not trigger the internal reset pulse unless there is another initialization.
Prescaler Value
P2 and P1 in the function latch set the prescaler values. The prescaler value should be chosen so that the prescaler output frequency is always less than or equal to 300 MHz. Thus, with an RF frequency of 4 GHz, a prescaler value of 16/17 is valid but a value of 8/9 is not valid.
*
PD Polarity
This bit sets the phase detector polarity bit. See Figure 19.
CE Pin Method
1. 2. 3. 4. 5. 6. Apply VDD. Bring CE low to put the device into power-down. This is an asynchronous power-down in that it happens immediately. Program the function latch (10). Program the R counter latch (00). Program the AB counter latch (01). Bring CE high to take the device out of power-down. The R and AB counters will now resume counting in close alignment.
CP Three-State
This bit controls the CP output pin. With the bit set high, the CP output is put into three-state. With the bit set low, the CP output is enabled.
INITIALIZATION LATCH
The initialization latch is programmed when C2 and C1 are set to 1 and 1. This is essentially the same as the function latch (programmed when C2, C1 = 1, 0). However, when the initialization latch is programmed, an additional internal reset pulse is applied to the R and AB counters. This pulse ensures that the AB counter is at load point when the AB counter data is latched and the device will begin counting in close phase alignment. If the latch is programmed for synchronous power-down (CE pin is high; PD1 bit is high; PD2 bit is low), the internal pulse also triggers this power-down. The prescaler reference and the oscillator input buffer are unaffected by the internal reset pulse and so close phase alignment is maintained when counting resumes. When the first AB counter data is latched after initialization, the internal reset pulse is again activated. However, successive AB counter loads after this will not trigger the internal reset pulse.
Note that after CE goes high, a duration of 1 s may be required for the prescaler band gap voltage and oscillator input buffer bias to reach steady state. CE can be used to power the device up and down to check for channel activity. The input register does not need to be reprogrammed each time the device is disabled and enabled as long as it has been programmed at least once after VDD was initially applied.
Counter Reset Method
1. 2. 3. 4. 5. Apply VDD. Do a function latch load (10 in 2 LSBs). As part of this, load 1 to the F1 bit. This enables the counter reset. Do an R counter load (00 in 2 LSBs). Do an AB counter load (01 in 2 LSBs). Do a function latch load (10 in 2 LSBs). As part of this, load 0 to the F1 bit. This disables the counter reset.
Device Programming after Initial Power-Up
After initially powering up the device, there are three ways to program the device.
Initialization Latch Method
1. 2. 3. 4. 5. Apply VDD. Program the initialization latch (11 in 2 LSBs of input word). Make sure that the F1 bit is programmed to 0. Next, do a function latch load (10 in 2 LSBs of the control word), making sure that the F1 bit is programmed to a 0. Then do an R load (00 in 2 LSBs). Then do an AB load (01 in 2 LSBs).
This sequence provides the same close alignment as the initialization method. It offers direct control over the internal reset. Note that counter reset holds the counters at load point and three-states the charge pump, but does not trigger synchronous power-down.
POWER SUPPLY CONSIDERATIONS
The ADF4108 operates over a power supply range of 3.2 V to 3.6 V. The ADP3300ART-3.3 is a low dropout linear regulator from Analog Devices. It outputs 3.3 V with an accuracy of 1.4% and is recommended for use with the ADF4108.
Rev. 0 | Page 17 of 20
ADF4108 INTERFACING
The ADF4108 has a simple SPITM-compatible serial interface for writing to the device. CLK, DATA, and LE control the data transfer. When LE (Latch Enable) goes high, the 24 bits that have been clocked into the input register on each rising edge of CLK are transferred to the appropriate latch. See Figure 2 for the timing diagram and Table 5 for the latch truth table. The maximum allowable serial clock rate is 20 MHz. This means that the maximum update rate possible for the device is 833 kHz or one update every 1.2 s. This is certainly more than adequate for systems that have typical lock times in hundreds of microseconds.
SCLOCK MOSI CLK DATA LE CE MUXOUT (LOCK DETECT)
06015-026
ADuC812
I/O PORTS
ADF4108
Figure 21. ADuC812 to ADF4108 Interface
ADSP-2181 INTERFACE
Figure 22 shows the interface between the ADF4108 and the ADSP-21xx Digital Signal Processor. The ADF4108 needs a 24-bit serial word for each latch write. The easiest way to accomplish this using the ADSP21xx family is to use the autobuffered transmit mode of operation with alternate framing. This provides a means for transmitting an entire block of serial data before an interrupt is generated. Set up the word length for 8 bits and use three memory locations for each 24-bit word. To program each 24-bit latch, store the three 8-bit bytes, enable the autobuffered mode, and then write to the transmit register of the DSP. This last operation initiates the autobuffer transfer.
SCLOCK MOSI CLK DATA LE CE I/O FLAGS
06015-027
ADuC812 INTERFACE
Figure 21 shows the interface between the ADF4108 and the ADuC812 MicroConverter(R). Since the ADuC812 is based on an 8051 core, this interface can be used with any 8051 based microcontroller. The MicroConverter is set up for SPI master mode with CPHA = 0. To initiate the operation, the I/O port driving LE is brought low. Each latch of the ADF4108 needs a 24-bit word. This is accomplished by writing three 8-bit bytes from the MicroConverter to the device. When the third byte has been written, the LE input should be brought high to complete the transfer. On first applying power to the ADF4108, it needs four writes (one each to the initialization latch, function latch, R counter latch, and N counter latch) for the output to become active. I/O port lines on the ADuC812 are also used to control powerdown (CE input) and to detect lock (MUXOUT configured as lock detect and polled by the port input). When operating in the mode described, the maximum SCLOCK rate of the ADuC812 is 4 MHz. This means that the maximum rate at which the output frequency can be changed will be 166 kHz.
ADSP-21xx TFS
ADF4108
MUXOUT (LOCK DETECT)
Figure 22. ADSP-21xx to ADF4108 Interface
Rev. 0 | Page 18 of 20
ADF4108 PCB DESIGN GUIDELINES FOR CHIP SCALE PACKAGE
The lands on the chip scale package (CP-20) are rectangular. The printed circuit board pad for these should be 0.1 mm longer than the package land length and 0.05 mm wider than the package land width. The land should be centered on the pad. This will ensure that the solder joint size is maximized. The bottom of the chip scale package has a central thermal pad. The thermal pad on the printed circuit board should be at least as large as this exposed pad. On the printed circuit board, there should be a clearance of at least 0.25 mm between the thermal pad and the inner edges of the pad pattern. This will ensure that shorting is avoided. Thermal vias can be used on the printed circuit board thermal pad to improve thermal performance of the package. If vias are used, they should be incorporated in the thermal pad at 1.2 mm pitch grid. The via diameter should be between 0.3 mm and 0.33 mm and the via barrel should be plated with 1 oz. copper to plug the via. The user should connect the printed circuit board thermal pad to AGND.
Rev. 0 | Page 19 of 20
ADF4108 OUTLINE DIMENSIONS
5.10 5.00 4.90
16 9
4.50 4.40 4.30
1 8
6.40 BSC
PIN 1 0.15 0.05 0.65 BSC 0.30 0.19 COPLANARITY 0.10 1.20 MAX
0.20 0.09
SEATING PLANE
8 0
0.75 0.60 0.45
COMPLIANT TO JEDEC STANDARDS MO-153-AB
Figure 23. 16-Lead Thin Shrink Small Outline Package [TSSOP] (RU-16) Dimensions shown in millimeters
4.00 BSC SQ 0.60 MAX PIN 1 INDICATOR TOP VIEW 3.75 BCS SQ 0.75 0.55 0.35 0.05 MAX 0.02 NOM COPLANARITY 0.08
11 10 6 5
0.60 MAX
16 15
PIN 1 INDICATOR
20 1
2.25 2.10 SQ 1.95 0.25 MIN 0.30 0.23 0.18
12 MAX 1.00 0.85 0.80 SEATING 0.50 PLANE BSC
0.80 MAX 0.65 TYP
0.20 REF
COMPLIANT TO JEDEC STANDARDS MO-220-VGGD-1
Figure 24. 20-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 4 mm x 4 mm Body, Very Thin Quad (CP-20-1) Dimensions shown in millimeters
ORDERING GUIDE
Model ADF4108BRUZ 1 ADF4108BRUZ-RL1 ADF4108BRUZ-RL71 ADF4108BCPZ1 ADF4108BCPZ-RL1 ADF4108BCPZ-RL71 EVAL-ADF4108EB1
1
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Description 16-Lead Thin Shrink Small Outline Package [TSSOP] 16-Lead Thin Shrink Small Outline Package [TSSOP] 16-Lead Thin Shrink Small Outline Package [TSSOP] 20-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 20-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 20-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board
Package Option RU-16 RU-16 RU-16 CP-20-1 CP-20-1 CP-20-1
Z = Pb-free part.
(c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06015-0-4/06(0)
Rev. 0 | Page 20 of 20

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