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Agamem Microelectronics Inc. PRELIMINARY
OVERVIEW
AA18375AP
Switching Regulator Controller
The AA18375AP is a two-channel PWM DC-DC converter control IC that features low-voltage operation. This IC can obtain the step-up, step-down and inverting voltages with a small number of external components. Because the IC is compactly packaged, it is best suited for use as a power supply in portable equipment.
FEATURES
* Wide supply voltage range: 3.6 V to 15 V * Low current consumption: 1.3 mA typical * Control in a wide output frequency range is possible (1 kHz to 500 kHz). * Timer latch, short-circuit protection circuit is built in. * Circuit to prevent malfunction during low input voltage is built in. * Built-in reference voltage (1.28V) output pin. * Dead time period is adjustable over the whole range of duty ratio. * Synchronization operation is possible.
PIN Configuration
(TOP VIEW) CT 1 RT 2 +IN1 3 -IN1 4 FB1 5 D.T.C.1 6 OUT1 7 GND 8 16 VREF 15 SCP 14 +IN2 13 -IN2 12 FB2 11 D.T.C.2 10 OUT2 9 VCC
APPLICATIONS
* LCD Displays * PDAs * Digital Still Cameras * Hand-held and portable instruments
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PIN DESCRIPTIONS
Pin No. Symbol I/O 1 2 3 4 5 6 7 8 CT RT +IN1 -IN1 FB1 D.T.C.1 OUT1 GND -- Description Pin No. Symbol 9 10 11 12 13 14 15 16 VCC OUT2 D.T.C.2 FB2 -IN2 +IN2 SCP VREF
AA18375AP
Switching Regulator Controller
I/O I O I O I I -- O Description IC power supply pin Output2 block push-pull type output pin PWM2 block dead-time setting pin Output pin of error amplifier 2 block Error amplifier 2 block inverting input pin Error amplifier 2 block non-inverting input pin Soft start and short circuit protection setting capacitor connection pin Reference voltage output pin
Pin for oscillation capacitor connection Pin for oscillation timing resistor -- connection Error amplifier 1 block I non-inverting input pin Error amplifier 1 block inverting I input pin Output pin of error amplifier 1 O block PWM1 block dead-time setting I pin Output1 block push-pull type O output pin -- Ground pin
BLOCK DIAGRAM
Vcc 9 CT 1 RT 2
VREF 16
1.28V
Reference Voltage Supply
2.5V
1.9V 1.3V
Triangular wave Oscillator
PWM Comp 1
Error Amp 1
+IN1 3 -IN1 4 FB1 5 FB2 12 +IN2 14 -IN2 13
+ -
+ _ _ + + _
S.C.P.Comp PWM Comp 2 1.1V
OUTPUT 1
7
+ _ _
OUTPUT 2
10
Error Amp 2
+ 1.28V 2.5V 0.9V R
S
SCP 15
R
0.9V
Latch
U.V.L.O
CLR
SET
Q
Q
+ + _
D.T.C. Comp 1.8V
8 GND
6
11
D.T.C. 1 D.T.C. 2
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Agamem Microelectronics Inc. PRELIMINARY
ABSOLUTE MAXIMUM RATING
AA18375AP
Switching Regulator Controller
(Ta = +25 C)
Parameter Power Supply Voltage Error Amp. Input Voltage Collector Output Voltage Collector Output Current Power Dissipation Operating Temperature Storage temperature
Symbol
VCC VI VO IO PD TOP Tstg
Condition Min
Ta +25C -0.3 -30 -55
Rating
Unit Max
18 +10 18 75 *430 +85 V V V mA mW C C
+125
*: The packages are mounted on the epoxy board (4 cm x 4 cm x 1.5 mm).
RECOMMENDED OPERATING CONDITIONS
Parameter Power Supply Voltage Error Amp. Input Voltage Collector Output Voltage Collector Output Current Phase Compensation Capacitor Timing Capacitor Timing Resistor Oscillator Frequency Reference Voltage Output Current Operating Temperature Symbol Min VCC VI VO IO CP CT RT fOSC IREF TOP 3.6 -0.2 - 0.3 - 150 5.1 1 -3 -30 Value Typ 6.0 - - - 0.1 - - - -1 25 Max 15 1.45 15 50 - 15000 100 500 - 85 V V V mA F pF k kHz mA
C
Unit
WARNING: The recommended operating conditions are required in order to ensure the normal operation of the semiconductor device. All of the device's electrical characteristics are warranted when the device is operated within these ranges.
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ELECTRICAL CHARACTERISTICS
Parameter Output Voltage Output Temp. Stability Reference Section Input Stability Load Stability Short Circuit Output Current Under Voltage Lockout Protection Section Threshold Voltage Hysteresis Width Reset Voltage (VCC) Input Threshold Voltage Input Stand by Voltage Protection Circuit Section Input Latch Voltage Input Source Current Comparator Threshold Voltage Oscillator Frequency Triangular Waveform Oscillator Section Frequency Deviation No pull up No pull up - Pin 5, Pin 12 CT = 330 pF, RT = 15 k CT = 330 pF, RT = 15 k condition IOR = - 1 mA Ta = - 30 C to +85 C VCC = 3.6 V to 15 V IOR = - 0.1 mA to - 1 mA VREF = 0 V IOR = - 0.1 mA IOR = - 0.1 mA IOR = - 0.1 mA - -
AA18375AP
Switching Regulator Controller
(Ta = +25 C, VCC = 6 V) Value Symbol Min Typ Max
VREF VRTC Line Load IOS VtH VtL VHYS VR VtPC VSTB VI Ibpc VtC fOSC fdev fdV fdT Vt0 Vt100 Ibdt Idt Vdt 1.26 1.28 0.2 2 1 1.30 2 10 7.5
Unit
V % mV mV mA V V mV V V mV mV A V kHz % % % V V A A V
-2 - - - - -
80 1.5 0.60
-30
2.72 2.60 120 1.9 0.65 50 50
-10 - - - -
0.7 100 100
- - -1.4 - - - - -4 -
0.2
-1.0
1.1 200 10 1
-0.6 - - - -
4
VREF -0.15
Frequency Stability (VCC) VCC = 3.6 V to 15 V Frequency Stability (Ta) Input Threshold Voltage Ta = - 30 C to +85 C Duty Cycle = 0 % Duty Cycle = 100 % - Vdt = 0.7 V Idt = - 40 A VO = 1.6 V VO = 1.6 V VO = 1.6 V VCC = 3.6 V to 15 V
-
1.0 0.4
Dead-Time (fOSC = 10 kHz) Control Input Bias Current Section Latch Mode Source Current Latch Input Voltage Error Amp. Input Offset Voltage Section Input Offset Current Input Bias Current Common Mode Input Voltage Range Voltage Gain Frequency Band Width
- -1 -80 - +10 +100 - +1.45 - -
- -
VREF-0.1
-0.2 -150 - - - -100 - 120 3
VIO IIO IB VICR AV
-10 -100 -500 -0.2 84 -
mV nA nA V V/V
MHz
AV = - 3 dB
BW
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Agamem Microelectronics Inc. PRELIMINARY
Common Mode Rejection Ratio Max Output Voltage Width Output Sink Current Output Source Current PWM Comparator Input Sink Current Section Input Threshold Voltage (fOSC=10 kHz) VO = 1.6 V VO = 1.6 V Duty Cycle = 0 % Duty Cycle = 100 %
Pin 5, Pin 12 = 1.6 V Pin 5, Pin 12 = 1.6 V
AA18375AP
Switching Regulator Controller
CMRR VOM+ VOM IOM+ IOM Vt0 Vt100 IIN+ IIN Leak VSAT ICCS ICCa 60 2.2 - 24 - - 1.05 24 - - - - - 80 2.4 0.7 50 -1.2 1.9 1.3 50 -1.2 - 1.1 1.3 1.7 - - 0.9 - -0.7 2.1 - - -0.7 10 1.4 1.8 2.4 dB V V A mA V V A mA A V mA mA
Input Source Current Output Section Output Leak Current
VO = 15 V
Output Saturation Voltage IO = 50 mA Output "OFF" RT = 15 k
Stand by Current Average Supply Current
TIMING DIAGRAM
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TYPICAL CHARACTERISTICS
AA18375AP
Switching Regulator Controller
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AA18375AP
Switching Regulator Controller
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OPERATION DESCRIPTION
1. Reference voltage
AA18375AP
Switching Regulator Controller
This block is composed of the band gap circuit, and outputs the temperature compensated 2.5 V reference from Vcc (pin 9) for use by internal circuits. A reference voltage of temperature compensated 1/2 Vref can be obtained to external circuit by Vref terminal (pin 16). 2. Oscillator The sawtooth-waveform-like triangular wave having a peak of approximately 1.9 V and a trough of approximately 1.3 V can be generated by connecting the timing capacitor CT (pin 1) and resistor RT (pin 2). The usable oscillation frequency is from 1 kHz to the maximum 500 KHz. The triangular wave is connected with the non-inverting input of PWM comparator for channel 1 side and channel 2 side within the IC inside. 3. Error amplifiers The output voltage of DC-DC converter is detected by the error-amplifier and the amplified signal is input to the PWM comparator. Also, it is possible to perform the gain setting and the phase compensation arbitrarily by connecting a resistor and a capacitor from the FB terminals (pins 5 and 12) to GND. The error amplifier output is internally connected to the inverting inputs of the PWM comparators and also to the short protection circuit. 4. Timer latch short protection circuit This circuit protects the external main switching devices, flywheel diodes, and choke coils, etc. from destruction or deterioration if overload or short-circuit condition of power supply output lasts for a certain time. The timer latch short-circuit protection circuit detects the output level of the error amplifier. If one or both error amplifier outputs are 1.1 V or lower, the low-level output is given and the timer circuit is actuated to start the charge of the external protection-enable capacitor. If the output level of the error amplifier does not drop below the normal voltage range before the capacitor voltage reaches the 1.19 V, it sets the latch circuit, and cuts off the output drive transistor, and sets the dead-time to 100%. 5. Under voltage lockout protection circuit This circuit protects the system from destruction or deterioration due to control malfunction when the supply voltage is low in the transient state of power on/off. The under voltage lockout protection circuit compares the internal reference voltage level with the supply voltage level. If the supply voltage level falls below the reference level it cuts off the output drive transistor, and sets the dead time to 100%. The protection enable terminal (pin 15) is pulled "Low". 6. PWM comparator Each PWM comparator has two inverting inputs and one non-inverting input. This voltage-to-pulse-width converter controls the output pulse width according to the input voltage. The PWM comparator turns the output drive transistor on when the oscillator triangular waveform is higher than the error amplifier output and the dead time control terminal voltage. 7. Output drive transistor This output circuit is open-collector type. The available output current is up to 50 mA. The breakdown voltage of output terminal is 15V.
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TEST CIRCUIT
DTC2 INPUT VCC
AA18375AP
Switching Regulator Controller
FB2 TEST SW 1.28V CPE
16 15 2
4.7K OUT2
+IN2
14
-IN2
13 12 5 11 10 9
4.7K
OUT1
AA18375AP 1 0.1uF +IN1 330pF 15K -IN1 FB1 TEST 3 4 6 DTC1 INPUT 7 8 GND
TYPICAL APPLICATION EXAMPLE
Chopper Type Step Down/Inverting
820pF 1 10K 2 3 2.3K 0.1uF 33K 1uF +33K 1uF +330 330 470 470 33K 4 5 6 7 8 16 0.1uF 15 14 13 0.1uF 12 11 10 9 5.6K 33K 220uF -+ 1.9K
Vin (10V) 56uH
AA18375AP
120uH 120uH Vout+(+5V)
9.1K Vout-(-5V)
220uF -+ GND
220uF -+
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AA18375AP
Switching Regulator Controller
Vin (5V)
Chopper Type Step Up/Inverting
820pF 1 10K 2 3 2.3K 0.1uF 33K 1uF +33K 1uF +330 330 33K 4 5 6 7 8 16 0.1uF 15 14 13 0.1uF 12 11 10 9 16K 33K 220uF -+ 1.9K
56uH
AA18375AP
3.9K 120uH 100 120uH
9.1K Vout-(-5V)
220uF -+ GND
220uF -+ Vout+(+12V)
Vin (5V)
Chopper Type Step Up/Inverting (For High Speed)
820pF 1 10K 2 3 2.3K 0.1uF 33K 1uF +33K 1uF +470 470 220 470 470 - 1uF + 33K 33K 220uF 330pF 150 33K 4 5 6 7 8 16 0.1uF 15 14 13 0.1uF 12 11 10 9 16K 33K 220uF -+ 1.9K
56uH
AA18375AP
120uH
120uH 9.1K Vout-(-5V) 220uF -+
Vout+(+12V)
-+ GND
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HOW TO SET OUTPUT VOLTAGE
AA18375AP
Switching Regulator Controller
The output voltage is set using the connection shown below. The error amplifiers are supplied to the internal reference voltage circuit as are the other internal circuits. The common-mode input voltage range is from - 0.2 V to +1.45 V. When the amplifiers are operated non-inverting, tie the inverting terminal to VREF 1.28 V). When the amplifiers are operated inverting, tie the non-inverting terminal to ground.
R2 + R1 Vref -
Vo+ [=Vref X (1+R2/R1)] PIN5 or PIN12
R2 R1 Vref +
Vo- [= -Vref X (R2/R1)] PIN5 or PIN12
HOW TO SET TIME CONSTANT FOR TIMER LATCH SHORT PROTECTION CIRCUIT
If the load condition drastically changes due to a load short-circuit and if low-level signals (1.1 V or lower) are input to the non-inverting inputs of the short-circuit protection comparator from the error amplifiers, the short circuit protection comparator outputs a "Low" level. The protection enable terminal voltage is discharged, and then the short-circuit protection comparator charges the externally connected protection enable capacitor CPE according to the following formula: -6 VPE = 50 mV + tPE x 10 /CPE -6 0.65 = 50 mV + tPE x 10 /CPE CPE = tPE/0.6 ( F) When the power supply is turned on, the output is considered to be short-circuited state so that the S.C.P. terminal voltage starts charging. It is necessary to set the external capacitor so as to start up the DC-DC converter output voltage before setting the latch circuit in the later stage. Especially, pay attention to the delay of the start-up time when applying the soft-start function.
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SYNCHRONIZATION OF ICs
AA18375AP
Switching Regulator Controller
Multiple instances of this IC can be operated in parallel. If the CT and RT terminals are connected to each other as shown below, the ICs will operate at the same frequency. Instead of applying VRT to the RT terminals, these terminals can be pulled up by a resistor (see resistance indicated by the dashed line in). Select the pull-up resistance Rpull from the formula given below.
Vcc 0.5 x N
Rpull
Rpull: Pull up Resistor (k) VCC: Power Supply Voltage (V) N: Number of Slave ICs
16
15
14
13
12
11
10
9
AA18375AP (MASTER)
1 2 3 4 5 6 7 8
Vcc
CT Rpull
16 15
RT
14
13
12
11
10
9
AA18375AP (SLAVE)
1 2 3 4 5 6 7 8
16
15
14
13
12
11
10
9
VRT 2V
AA18375AP (SLAVE)
1 2 3 4 5 6 7 8
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PACKAGE
AA18375AP
Switching Regulator Controller
AA18375AP - 16-pin Plastic TSSOP
C
L
E1
E
AA18375AP
theta
12(4X)
D
DIMENSIONS IN MILLIMETERS MIN NOM MAX --0.05 0.80 0.19 0.09 4.90 6.20 4.30 --0.45 --0 ----1.00 ----5.00 6.40 4.40 0.65 0.60 ----1.20 0.15 1.05 0.30 0.20 5.10 6.60 4.50 --0.75 0.10 8
A1
A A2
e
b
SYMBOLS A A1 A2 b C D E E1 e L y theta
DIMENSIONS IN INCHES MIN NOM MAX --0.002 0.031 0.007 0.004 0.193 0.244 0.169 --0.018 --0 ----0.039 ----0.197 0.252 0.173 0.026 0.024 ----0.048 0.006 0.041 0.012 0.008 0.201 0.260 0.177 --0.030 0.004 8
NOTE 1. PACKAGE BODY SIZES EXCLUDE MOLD FLASH PROTRUSIONS OR GATE BURRS 2. TOLERANCE 0.1 mm UNLESS OTHERWISE SPECIFIED 3. COPLANARITY : 0.1 mm 4. CONTROLLING DIMENSION IS MILLIMETER. CONVERTED INCH DIMENSIONS ARE NOT NECESSARILY EXACT. 5. FOLLOWED FROM JEDEC MO-153
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NOTES ON USE
AA18375AP
Switching Regulator Controller
* The information described herein is subject to change without notice. * The specifications for the product described in this document are for reference only. Upon actual use, therefore, please request that specifications to be separately delivered. * The application circuit examples explain typical applications of the products, and do not guarantee the success of any specific mass-production design. * Application circuit diagrams and circuit constants contained herein are shown as examples of standard use and operation. Please pay careful attention to the peripheral conditions when designing circuits and deciding upon circuit constants in the set. * Take account of common impedance when designing the earth line on a printed wiring board.
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