View SIP2803_253078.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

SiP2800/01/02/03/04/05
New Product
Vishay Siliconix
Low Power Consumption Current Mode Controller
FEATURES
D D D D D D Pin-for-Pin Compatible with UCC280X Controllers Enhanced Performance UC284X for New Designs 100-mA Typical Start-Up Current 500-mA Typical Operating Current Internal Soft Start at Power-On and After Fault 100-ns Internal Leading Edge Blanking
APPLICATIONS
D D D D D Efficiency-Enhanced DC/DC Converter Modules Low Quiescent Current Standby Power Supplies Offline (AC/DC) Power Supplies Universal Input Power Supplies Buck, Boost, and Buck-Boost Converters
DESCRIPTION
The SiP280X family includes six high-speed, low power consumption, BiCMOS Current Mode Controllers. These integrated circuits contain all of the control and drive functions required for off-line and dc-to-dc current-mode switching power supplies. Their advanced architecture enables the implementation of full-featured designs with minimal external parts count. Maximum Duty Cycle
100% 50% 100% 100% 50% 50%
The SiP280X family controllers are available in both standard and lead (Pb)-free, SO-8 and TSSOP-8 packages, and are rated for operation over the industrial temperature range of --40 to 85 _C.
Part Number
SiP2800 SiP2801 SiP2802 SIP2803 SiP2804 SiP2805
Reference Voltage
5V 5V 5V 4V 5V 4V
Turn-On Threshold
7.2 V 9.4 V 12.5 V 4.1 V 12.5 V 4.1 V
Turn-Off Threshold
6.9 V 7.4 V 8.3 V 3.6 V 8.3 V 3.6 V
TYPICAL APPLICATION CIRCUIT
+48 V +
+
12 V/3 A
+
FB
VCC
COMP
SiP2801
RC REF GND
OUT CS
GND Flyback Converter for Point of Load Application
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
www.vishay.com
1
SiP2800/01/02/03/04/05
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 V FB, Comp, CS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . --0.3 V to 6 V Power Disispation SO-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 W Power Disispation TSSOP-8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 830 mW StorageTemperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . --55 to 150_C
New Product
Currents are positive into, negative out of the specificed terminal.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING RANGE
Input Voltage SIP2803/5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 to 11 V Input Voltage SiP2800/1/2/4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 to 11 V Operating Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . --40 to 85_C
SPECIFICATIONS
Test Conditions Unless Specified Parameter Reference
ILOAD = 0 2 mA TA= 25 C 0.2 mA, Reference Voltage VREF SiP2800/1/2/4 SIP2803/5 Load Regulation Line Regulation Noise Short Circuit Current VLOAD VLINE VNOISE ISC 0.2mA< ILOAD <5mA Vcc=10 V to Clamp , TA = 25 C Vcc=10 V to Clamp 10 Hz < f < 10 kHz, TA = 25 C kHz 130 --5 --35 SiP2800/1/2/4 SIP2803/5 4.925 3.940 4.88 3.90 5.000 4.000 5.00 4.00 10 5.075 4.06 5.10 4.08 30 1.9 2.5 mV/V mV mA mV V
Limits Mina Typb Maxa Unit
Symbol
VCC = 10 V, RT = 100 k, CT = 330 pF CREF = 0.1 mF, --40 _C < TA < 85 _C
Oscillator
Frequency Temperature Stability Amplitude Peak Voltage VP--P VP 2.25 fOSC SiP2800/1/2/4 SIP2803/5 40 26 46 31 2.5 2.40 2.45 2.55 V 52 36 kHz %
Error Amplifier
Input Voltage Input Bias Current Open Loop Gain COMP Sink Current COMP Source Current Gain Bandwidth VIN IBIAS1 AV ISINK ISOURCE BW FB = 2.7 V, COM P= 1.1 V FB = 1.8 V, COMP = VREF -- 1.2 V COMP = 2.5 V COMP = 2.0 V SiP2800/1/2/4 SIP2803/5 2.44 1.95 --1 60 0.3 --0.2 --0.5 2 80 3.5 --0.8 mA MHz 2.50 2.00 2.56 2.05 1 V mA dB
PWM and Overcurrent Comparator
Maximum Duty Cycle Minimum Duty Cycle Gainc Max. Input Signal Input Bias Current 2 www.vishay.com DMAX DMIN AV VIMAX IBIAS2 COMP = 0 V 0 < VCS < 0.8 V COMP = 5 V 1.2 0.9 --200 1.65 1.0 SiP2800/2/3 SiP2801/4/5 97 48 99 49 100 50 0 1.9 1.1 200 V/V V nA %
2
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
SiP2800/01/02/03/04/05
New Product
SPECIFICATIONS
Test Conditions Unless Specified Parameter
COMP to CS Offset CS Pin Blanking Time Overcurrent Comparator Fault Threshold
Vishay Siliconix
Limits Mina
0.45 50 1.47
Symbol
VCC = 10 V, RT = 100 k, CT = 330 pF CREF = 0.1 mF, --40 _C < TA < 85 _C
Typb
0.90 100
Maxa
1.35 150 1.73
Unit
V ns
PWM and Overcurrent Comparator
CS = 0 V
Output
I = 20 mA VOL Output Voltage p g I = 200 mA I = 50 mA, VCC = 5 V I = 20 mA, VCC = 0 V I = --20 mA VCC -- VOH Rise Time Fall Time tr tf CL= 1 nF I = --200 mA I = --50 mA, VCC = 5 V All Parts SIP2803/5 All Parts SIP2803/5 All Parts 0.1 0.35 0.15 0.70 0.15 1.00 0.40 41 44 0.40 0.90 0.40 1.20 0.40 1.90 0.90 70 75 ns V
Undervoltage Lockout
SiP2800 Start Thresholdd VSTART SiP2801 SiP2802/4 SIP2803/5 SiP2800 Stop Thresholdd SiP2801 VSTOP SiP2802/4 SIP2803/5 SiP2800 SiP2801 Start to Stop Hysteresis VHYS SiP2802/4 SIP2803/5 6.6 8.6 11.5 3.7 6.3 6.8 7.6 3.2 0.05 1.5 3.0 0.2 7.2 9.4 12.5 4.1 6.9 7.4 8.3 3.6 0.30 2.0 4.2 0.5 7.8 10.2 13.5 4.5 7.5 8.0 9.0 4.0 0.48 2.4 5.1 0.8 V
Soft-Start
COMP Rise Time SS FB = 1.8 V, Rise from 0.5 V to VREF --1 V 4 10 ms
Overall
Start-up Current Operating Supply Current Vcc Internal Zener Voltaged Vcc Internal Zener Voltage Minus Start Threshold Voltaged ISTART ICC VZ VZ --VSTART Vcc < Start Threshold FB = 0 V, CS = 0 V ICC = 10 mA SiP2802/04 12.0 0.5 0.1 0.5 13.5 1.0 0.2 1.0 15.0 V mA
Notes a. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum (--40_ to 85_C). b. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing and are measured at VCC = 12 V unless otherwise noted. c. Gain is defined by A = VCOMP/VCS , 0 V VCS 0.8 V. d. Start, Stop, and Zener voltages track each other.
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
www.vishay.com
3
SiP2800/01/02/03/04/05
Vishay Siliconix
TYPICAL CHARACTERISTICS
SiP2800/01/02/04 Oscillator Frequency vs. Rt and Ct
1000 1000
New Product
SIP2803/05 Oscillator Frequency vs. Rt and Ct
Oscillator Frequency (kHz)
100 Ct = 100 pF Ct = 200 pF Ct = 330 pF 10 10 100 Rt (k) Ct = 1000 pF 1000
Oscillator Frequency (kHz)
100
Ct = 100 pF Ct = 200 pF Ct = 330 pF Ct = 1000 pF 10 100 Rt (k) 1000
10
Oscillator Dead Time vs. Ct
500 450 400 350 Dead Time (nS) 300 250 200 150 100 50 0 100 SiP2800/01/02/04 SIP2803/05 Rt = 100 k 1.2 COMP to CS Offset (V) 1.3
COMP to CS Offset Voltage vs. Temperature
CS = 0 V
1.1
1.0
0.9
0.8
200
300
400
500
600
700
800
900 1000
0.7 --50
--25
0
25
50
75
100
125
150
Ct (pf)
Temperature (_C)
Error Amplifier Gain and Phase vs. Frequency
80 70 60 50 Phase Gain (dB) 40 30 Gain 20 10 0 --10 --20 --30 1 10 100 Frequency (kHz) 1000 10000 --45 0 45 90 Phase (_) Document Number: 72660 S-41623--Rev.C, 30-Aug-04 135
www.vishay.com
4
SiP2800/01/02/03/04/05
New Product
PIN CONFIGURATION
Vishay Siliconix
SOIC-8
COMP FB CS RC 1 2 3 4 8 7 6 5 REF VCC OUT GND COMP FB CS RC 1 2 3 4 D
TSSOP-8
8 REF 7 VCC 6 OUT 5 GND Top View
Top View
ORDERING INFORMATION
SOIC-8 Part Number
SiP2800DY-T1 SiP2801DY-T1 SiP2802DY-T1 SIP2803DY-T1 SiP2804DY-T1 SiP2805DY-T1
TSSOP-8 Marking
2800 2801 2802 2803 2804 2805 --40 to 85_C 40
Lead (Pb)-Free Part Number
SiP2800DY-T1--E3 SiP2801DY-T1--E3 SiP2802DY-T1--E3 SIP2803DY-T1--E3 SiP2804DY-T1--E3 SiP2805DY-T1--E3
Temperature
Part Number
SiP2800DQ-T1 SiP2801DQ-T1 SiP2802DQ-T1 SIP2803DQ-T1 SiP2804DQ-T1 SiP2805DQ-T1
Lead (Pb)-Free Part Number
SiP2800DQ-T1--E3 SiP2801DQ-T1--E3 SiP2802DQ-T1--E3 SIP2803DQ-T1--E3 SiP2804DQ-T1--E3 SiP2805DQ-T1--E3
Marking
2800 2801 2802 2803 2804 2805
Temperature
--40 to 85_C 40
Additional voltage options are available.
PIN DESCRIPTION
Pin Number
1 2 3 4 5 6 7 8
Name
COMP FB CS RC GND OUT VCC REF Inverting input of the Voltage Error Amplifier
Function
Output of the Voltage Error Amplifier, and the inverting input to the PWM's Current Sense Comparator
Non-inverting input of the PWM Current Sense Comparator, and inverting input of the Overcurrent Fault Comparator (both comparators are fed from the output of the internal 100-ns Leading Edge Blanking circuit) Connection for the PWM Oscillator's timing resistor and timing capacitor Ground Pin. PWM Output Signal (capable of driving 750 mA into the gate of an external MOSFET power switch) Positive supply voltage for the IC IC Reference Voltage
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
www.vishay.com
5
SiP2800/01/02/03/04/05
Vishay Siliconix
DETAILED PIN DESCRIPTION
COMP COMP is the output of the Voltage Error Amplifier (VEA). The VEA is a low output impedance operational amplifier, providing the input to the PWM cycle-by-cycle current limit comparator. As the SiP280X series of parts use a true operational amplifier for the VEA, the COMP terminal can both source and sink current. To add flexibility to these parts, the VEA is internally current limited, which allows OUT to be forced to zero duty cycle by taking the COMP pin to GND. The voltage on COMP is passed through an internal diode to develop an offset voltage of approximately 0.6 V, and then through a resistive divider with a gain of 0.606-V/V, before being presented to the control input of the cycle-by-cycle current limit comparator. Clamping the COMP pin to less than the diode's forward voltage (i.e., <0.5 V) will command the current loop to deliver 0 A, by holding the control input of the cycle-by-cycle current comparator at 0 V. Similarly, the current loop will command the maximum inductor current on each cycle when COMP is at 2.25 V or greater, which drives the control input of the cycle-by-cycle current comparator to 1 V (since [2.25 V -- 0.6 V] x0.606 V/V = 1 V). The SiP280X series additionally features a built-in soft-start function, which functions by clamping the output level of the VEA to an internally generated voltage. This clamp will hold COMP at a low voltage (VCOMP 0 V) until VCC and VREF are at their proper levels. When these levels are appropriate for circuit operation, the internal voltage will begin rising, at the rate of 1 V/ms. This rising clamp level allows the voltage on the COMP pin to rise, which in turn allows the voltage at the control input of the cycle-by-cycle current comparator to increase. The maximum soft-start interval occurs under conditions requiring full duty cycle (50% or 100%, depending upon the part type), and is given by the time required for the voltage on the cycle-by-cycle current comparator's control input to reach 1 V. Since 1 V at the control input to the comparator requires that the COMP pin be at 2.25 V, the maximum soft-start interval is approximately 2.25 ms. CS Input to both the cycle-by-cycle and overcurrent fault current sense comparators. The cycle-by-cycle current limit comparator is the mechanism by which the VEA's output voltage commands the level of inductor or transformer current during a given "on" interval, thereby regulating the overall circuit's output. This comparator forms the inner loop of the two loops used in current-mode regulation. The overcurrent comparator has a trip threshold that is 50% higher than that of the cycle-by-cycle comparator. Under normal operating conditions, this comparator will not trip: its purpose is to provide enhanced protection of the power path components during severe faults (e.g., a short circuit). If the overcurrent comparator is tripped by a fault condition, it will command the SiP280X to do a "full-cycle restart." During this restart, the power supply will be quickly driven to the "off" state, and will be required to wait for five milliseconds (typical) before restarting. When the supply does restart, it will do so using the built-in soft-start function of the SiP280X.
www.vishay.com
New Product
The SiP280X family incorporates internal leading-edge blanking on the CS pin, to keep any spurious voltages on the CS pin from reaching the comparator inputs during the 100-ns interval immediately following the rising edge on OUT (for example, voltages due to capacitive charging currents). Because of this internal leading-edge blanking, many applications require no external RC filter on the CS input. Compared to circuits requiring the use of an external RC filter circuit, leading-edge blanking provides a shorter effective CS to OUT propagation delay. FB FB is the inverting input of the VEA. Internally compared against VREF/2 appearing on the VEA's non-inverting input. To avoid stability problems, keep lead lengths to FB as short as possible, and use good layout practices to minimize the stray capacitances of components connected to this pin. GND The GND pin is both the reference ground and the power ground for this part. OUT OUT is the output of a high-current driver capable of peak currents in excess of 750 mA. OUT is therefore well suited to driving the gates of power MOSFETs. This pin is specifically held low when VCC is below the SiP280X's UVLO threshold, to ensure a predictable system turn-on. Since the OUT pin is internally connected to a low impedance CMOS buffer, it is capable of rapid rail-to-rail transitions. This output topology also mitigates the effects of undershoot and overshoot. For this reason, external Schottky clamp diodes are generally not required on this pin. RC RC is the oscillator frequency programming pin. FOSC is set by the combination of RT and CT. The charging current for CT is provided through RT, which is normally connected between REF and the SiP280X RC pin. CT then connects from RC to GND. Due to the high impedances encountered in low power control circuits, this connection must be a short and quiet return to GND (preferably by means of a dedicated signal trace, separated from all other circuit functions). The oscillator frequency for the SiP280X family of parts is approximated by the following formulas: For the SiP2800, SiP2801, SiP2802, and SiP2804: D FOSC (1.5)/RTCT For the SIP2803 and SiP2805: D FOSC (1.0)/RTCT Here RT is in ohms and CT is in farads. More accurate formulas for FOSC are: For the SiP2800, SiP2801, SiP2802 and SiP2804: D FOSC = 1/{[(CT + CSTRAY) x RT x 0.652] + [(CT + CSTRAY) x RDISCH x 2.53] + TDELAY}
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
6
SiP2800/01/02/03/04/05
New Product
Vishay Siliconix
For the SIP2803 and SiP2805: D FOSC = 1/{[(CT + CSTRAY) x RT x 0.93] + [(CT + CSTRAY) x RDISCH x 2.53] + TDELAY} Here RT is in ohms and CT is in farads, RDISCH is the value of the resistor through which CT is discharged (normally an on-chip 130- resistor, unless the circuit is configured with additional external discharge-path resistance), and tDELAY is an inherent internal comparator delay time of 100 ns. The capacitance associated with the RC pin is approximately 7.5 pF, and should be included as a part of CSTRAY. Note that the SiP2801, SiP2804, and SiP2805 have an internal toggle flip-flop at the output of the oscillator, to ensure that the output duty cycle never exceeds 50%. This divides the frequency appearing at the OUT pin to one-half of the oscillator frequency for these three parts. Values of RT below 10 k are not recommended. Low values of RT cause high circuit operating currents, and very low values will prevent the oscillator from properly discharging CT. REF The reference generator block of the Si280X provides an accurate and stable 4.0 V or 5.0 V (depending upon part number), which is available at this pin of the IC. This voltage is also used internally for other functions on the IC. One of these uses is as the logic power supply for high speed switching logic on the IC; this, and stability concerns, make it important to bypass VREF to GND with a good quality 0.1-mF ceramic capacitor, as close to the part as possible. An electrolytic or tantalum capacitor may be used in addition to the ceramic capacitor. When 1 V < VCC < the UVLO threshold, REF is pulled to ground through a 5-k resistor. Hence, REF can also be used as an output to indicate the part's VCC status. VCC VCC is the positive power connection for the SiP280X controller IC, and should be the most positive terminal on the part. In normal operation, VCC is powered through a current limiting resistor. The required start-up supply current will generally be on the order of 100 mA with VCC below the UVLO voltage of the SiP280X, and can remain at or below 500-mA total supply current once the part starts switching. To prevent the IC from being damaged by overvoltage conditions, each of the SiP2800 family of parts has an internal clamp (effectively
a 12.5-V Zener diode) between VCC and GND. If the part's VCC pin is current-fed through an appropriate dropping resistor, the VCC pin will never exceed its rated voltage, nor will the the device as a whole exceed its rated power dissipation. This does require knowing what the operating current of the IC will be, so that the value of the dropping resistor can be calculated. A good estimate of the actual operating current (ICC) may be made by summing three components: (a) Any external current loading on the VCC or REF pins (b) The operating current required by the IC itself, and (c) The drive current (IDRIVE) required by the external power switch. Item (a) in the above list is a static dc value, and can generally be calculated with good accuracy. Item (b) will increase with operating frequency, but will be fixed for a given value of FOSC. Item (c) is usually the dominant term in the calculation of ICC, as the power required to drive the external power switch will typically increase as FOUT is increased. The most common example of this is seen in driving the gate of a power MOSFET. In such applications, the gate capacitances must be charged once each switching cycle. This calculation is simplified by using the gate charge term given by most MOSFET manufacturers, allowing the use of the formula: IDRIVE = FOUT x Qg of the chosen MOSFET. A first approximation of the necessary dropping resistor value is then given by: R = [(Nominal VSUPPLY) - 12 V]/(Nominal ICC) Here R is in ohms and ICC is in amperes. The resistor limiting the current into the VCC pin should be selected such that ICC(min) equals the worst-case maximum sum of the above currents, while holding ICC(max) to as low a value above that number as practicable (for best overall efficiency), and never more than 25 mA above that number (to avoid exceeding the IC's internal clamp diode ratings). VCC must be bypassed to GND with a good quality 0.1-mF ceramic capacitor, as close to the part as possible. This will help avoid problems created by high-frequency noise on the power supply of the part. An electrolytic or tantalum capacitor may be placed in parallel with the ceramic capacitor if more capacitance is needed or desired.
Document Number: 72660 S-41623--Rev.C, 30-Aug-04
www.vishay.com
7
SiP2800/01/02/03/04/05
Vishay Siliconix
FUNCTIONAL BLOCK DIAGRAM
New Product
VCC REF
Reference Voltage
Overcurrent Comparator -+ 1.5 V SiP2801/4/5 Only TQ Leading Edge Blanking CS
UVLO 13.5 V
COMP FB
OUT Voltage Error Amplifier -REF/2
SQ + -PWM Comparator OSC R
+
Soft-Start GND
RC
www.vishay.com
8
Document Number: 72660 S-41623--Rev.C, 30-Aug-04

▲Up To Search▲

Price & Availability of SIP2803

	To Download SIP2803 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .