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| www.fairchildsemi.com KA3502 PC SMPS Supervisory IC Features * * * * * * * * * * Complete Housekeeping Circuit Few External Components Over Voltage Protection for 3.3V/5V/12V/Adj. Output Over Current Protection for 3.3V/5V/12V Output Open-Collector Output and Remote On/Off Function Remote On/Off Delay Time Control Precision Voltage Reference for Outputs, 5V/12V Uncommitment Precision Voltage Reference for +5Vs Power Good Signal Generator with Hysteresis Disable Logic of 3.3V, 5V, 12V for Complete Shutdown Descriptions The KA3502 is complete housekeeping circuitry for use in the secondary side of SMPS(Switched Mode Power Supply). It contains various functions, which are two Precision Voltage References, Over Voltage/Current Protection, Remote On/Off Control, Power Good Signal Generator, Disable Logic and etc. 20-DIP 1 Internal Block Diagram V33 V5 V12 123 PWM FB1 VREF1 UV 14 11 6 15 VCC 5 R3 R1 R5 Vcc Adj 4 R2 R4 R6 + + + + 1.26V COMP1 Ion R8 1k R10 39k Ichg R15 5.1k 9 R9 10k R13 Vcc 5.2V + COMP9 Q3 PG Tsur 17 2.7V IS5 19 -+ 50mV IS33 20 -+ 135mV IS12 18 Vcc + COMP2 Vcc + COMP3 Vcc + - + - COMP4 65mV Vcc + 2V S Vcc Q R Q1 REFERENCE1 + COMP7 Vcc + COMP8 R12 2V1.3V Q2 COMP5 Vcc Vcc + COMP6 1.4V Ion+ Ioff 2.8V + 2V0.7V R11 5.4k 12 FB2 1.28V1.24V 13 VREF2 R14 REFERENCE2 R7 7 REM 8 Trem 16 GND 10 Topr Rev. 5.0 (c)2000 Fairchild Semiconductor International KA3502 Pin Assignments #1 V33 #20 IS33 V5 IS5 V12 IS12 Adj Tsur VCC PWM K A 3 5 0 2 GND FB1 REM VREF1 Trem VREF2 PG FB2 Topr #10 UV #11 NO 1 2 3 4 5 6 7 8 9 10 NAME V33 V5 V12 Adj VCC PWM REM Trem PG Topr FUNCTION +3.3 V OUTPUT VOLTAGE +5 V OUTPUT VOLTAGE +12 V OUTPUT VOLTAGE ADJUSTABLE OVP INPUT SUPPLY VOLTAGE REMOTE ON/OFF OUTPUT REMOTE ON/OFF INPUT REMOTE ON/OFF DELAY POWER GOOD OUTPUT PG DELAY NO 11 12 13 14 15 16 17 18 19 20 NAME UV FB2 VREF2 VREF1 FB1 GND Tsur IS12 IS5 IS33 FUNCTION PG INPUT for Det FEEDBACK for REFERENCE 2 PRECISION REFERENCE PRECISION REFERENCE FEEDBACK for REFERENCE 1 GROUND OCP DELAY Current INPUT for +12V Current INPUT for +5V Current INPUT for +3.3V 2 KA3502 Pin Description Pin Number 1 2 3 4 5 6 Pin Name V33 V5 V12 ADJ VCC PWM Pin Function Descrition +3.3 V Output Voltage of SMPS Secondary side +5 V Output Voltage of SMPS Secondary side +12 V Output Voltage of SMPS Secondary side Adjustable OVP Input. Its Threshold Voltage is 1.26 V. This pin can be used for another protection signal. Supply Voltage. Operating range is 15 V ~ 24 V. Vcc=18 V, Ta=25C at test. Remote On/Off Output. This signal controls the primary power switch (PWM IC) through an Opto-coupler. Maximum current rating is 30 mA. When PWM="Low", the main SMPS is operational and If PWM="High", the main SMPS is turned-off. Remote On/Off Input. It is TTL operation and its threshold voltage is 1.4 V. Voltage at this pin can reach normally 4.6 V, with absolutely maximum voltage, 5.25 V. If REM="Low", PWM="Low". That means the main SMPS is operational. When REM ="High", then PWM="High" and the main SMPS is turned-off. Remote On/Off delay. Ton/Toff=8 ms/24 ms (Typ.) with Ctrem=0.1uF. Its High/Low threshold voltage is 2 V/0.7 V and the maximum voltage after full charging is about 2.8 V. So, V (Chg.) = 2 V, V (Dischg.) = 2.1 V Typ. Power Good output signal. PG="High" means that the power is "Good" for operation and PG="Low" means "Power Fail". PG Delay. Td=250 ms (Typ.) with Ctopr=2.2uF. The High/Low threshold voltage are 2 V/1.3 V and the voltage of PIN 10 is clamped at 5.2 V for Noise margin. Under-Voltage Detect Pin. Its threshold voltage is 1.26V 20mV Typ. Feedback for Precision Reference2. Absolute min/max current rating is 1 mA/30 mA. Precision Reference 2 input Voltage. This circuit equals to KA431 and it is designed for an Auxiliary voltage, +5 Vs. It is trimmed to 1.6%. Precision Reference 1 Input Voltage. This circuit equals to KA431 and it is for corrective output voltages of +5 V/+12 V. It's trimmed to 1.6%. Feedback for Precision Reference1. Absolute min/max current rating is 2 mA/30 mA because of internal connection. Ground Timing pin for Over Current Protection blank-out time. Its threshold voltage is 2 V and clamped at 2.7 V after full charging. Target of delay time is 20 ms~30 ms and it is realized through external R & C. Current Sense Input for +12V. This pin is connected to the Current Sensing resistor or inductor. If the voltage drop of the resistor or inductor is larger than the fixed offset voltage ( 65 mV Typ.), PWM becomes "High" after some delay and the main SMPS is turned-off. Current Sense Input for +5 V. The OCP Offset voltage for +5 V is 50 mV Current Sense Input for +3.3 V. The OCP Offset voltage for +3.3 V is 135 mV 7 REM 8 Trem 9 10 11 12 13 14 15 16 17 PG Topr UV FB2 VREF2 VREF1 FB1 GND Tsur 18 19 20 IS12 IS5 IS33 3 KA3502 Absolute Maximum Ratings Parameter Supply Voltage UV Input Voltage Input Maximum Voltage Cathode Current for FB1, 2 PWM Maximum Current PG Output Maximum Current Power Dissipation Operating Temperature Range Storage Temperature Range Symbol Vcc Vuv Vin (max) Ik1, 2 Io (PWM) Io (PG) Pd Topr Tstg Value 15 ~ 24 24 Vcc - 3 1 ~ 30 30 30 1 0 ~ 70 -65 ~ 150 Unit V V V mA mA mA W C C Temperature Characteristics Parameter Temperature Stability for Vref1, 2 (0C Ta 70C) Symbol Vref1, 2 Value 17 Unit mV 4 KA3502 Electrical Characteristics (Vcc = 18V, Ta = 25C) Parameter PROTECTION SECTION Over Voltage Protection For 3.3 V Over Voltage Protection For 5 V Over Voltage Protection For 12 V OVP Input Threshold Voltage for Adj Comparator Offset Voltage for 3.3 V Comparator Offset Voltage for 5 V Comparator Offset Voltage for 12 V OCP Delay Comparator Input Threshold Voltage Pin 17 (Tsur) Input Clamp Voltage REMOTE ON/OFF SECTION Remote On/off Input Threshold Vtg. Remote On/off Input Open Voltage Remote On/off Input Low Current ON Delay Time OFF Delay Time PWM Saturation Voltage PWM Leakage Current REFERENCE 1 SECTION Reference Input Voltage 1 Line Regulation 1 Current Stability 1 Output Sinking Current Capability 1 Absolute Precision of Internal Three Resistors Matching Coefficient of Internal Three Resistors Temperature Stability Gain Bandwidth 1 Vref1 Vref1 (line) Vref1 Isink1 Rint Rrate Vref1 GBW1 IIk1=1 mA 15 V KA3502 Electrical Characteristics (Continued) Parameter REFERENCE 2 SECTION Reference Input Voltage 2 Line Regulation 2 Current Stability 2 Output Sinking Current Capability 2 Temperature Stability 2 Gain Bandwidth 2 POWER GOOD SECTION Detecting UV Voltage Detecting V5 Voltage Hysteresis Voltage 1 Hysteresis Voltage 2 High Threshold Voltage of Comp 9 Noise margin of Vtopr Charging Current for PG Delay Turn-On Delay Time for PG UV Input Pull Down Resistor PG Output Rising Time PG Output Falling Time PG Output Saturation Voltage PG Output Voltage at High Status DISABLE SECTION Disable Saturation Voltage for V33 Disable Saturation Voltage for V5 Disable Saturation Voltage for V12 TOTAL STANDBY CURRENT Supply Current Of Vcc Icc Vcc=18 V, REM=2V 5 10 mA Note: 1.These parameters, although guaranteed, but not 100% tested in production. Symbol Vref2 Vref2 (line) Vref2 Isink2 Vref2 GBW2 Vuv Vin (V5) HY1 HY2 Vth (H) Vtopr Ichg Topr Ruv Tr Tf Vsat (PG) Vpgh Vdis33 Vdi5 Vdis12 Condition IIk2=1 mA 15 V Typ. 2.50 1 5 25 13 1 1.26 4.3 40 0.7 2.0 4 -18 250 20 1 300 0.3 0.2 0.2 0.2 Max. 2.54 20 17 1.30 4.5 80 2.2 -28 500 0.4 5.25 0.4 0.4 0.4 Unit V mV/V mV mA mV MHz V V mV V V V uA msec kohm usec nsec V V V V V 6 KA3502 Typical Characteristics 2.510 2.53 2.505 Vref1, 2 (V) 0 25 50 75 100 2.52 Vref (V) 2.500 2.51 2.495 2.50 2.490 -25 2.49 0 5 10 15 1k (mA) 20 25 30 Temp (Dgree) Figure 1. Temperature Stability for Vref1,2 1.260 Figure 2. Vref1,2 Current Stability 20 1.255 15 Vadj (V) 1.250 PWM (V) 0 25 50 75 100 10 1.245 5 1.240 -25 0 1.10 1.15 1.20 1.25 1.30 1.35 Temp (Degree) Vadj (V) Figure 3. Bandgap Voltage (Vadj) 20 Figure 4. OVP Input Threshold Voltage for Adj 20 15 15 PWM (V) 10 PWM (V) 3.75 4.00 4.25 4.50 10 5 5 0 3.50 0 5.0 5.5 6.0 6.5 7.0 V33 (V) V5 (V) Figure 3. Over Voltage Protection for +3.3V Figure 4. OCP Offiset Voltage for 3.3V 7 KA3502 Typical Characteristics (Continued) 20 20 Vos33=IS33-V33 15 15 PWM (V) 10 PWM (V) 13 14 15 16 10 5 5 0 12 0 110 120 130 140 150 V12 (V) Vos33 (mV) Figure 7. Over Voltage Protection for +12V 20 Vos5=IS5-V5 15 Figure 8. OCP Offiset Voltage for 3.3V 20 Vos=IS12-Vo12 15 PWM (V) PWM (V) 10 10 5 5 0 40 45 50 55 60 0 55 60 65 70 75 Vos5 (mV) V8 (V) Figure 9. OCP Offiset Voltage for 5V 20 20 Figure 10. OCP Offiset Voltage for 12V 15 15 PWM (V) 10 PWM (V) 0.5 1.0 1.5 2.0 10 5 5 0 0.0 0 0.0 0.5 1.0 1.5 2.0 2.5 Vth (V) V8 (V) Figure 11. Remotr On/Off Input Threshold Figure 12. ON/OFF Delay Threshold Voltage 8 KA3502 Typical Characteristics (Continued) 25 6 5 4 20 PWM (V) PG (V) 0 5 10 15 20 15 3 2 10 5 1 0 1.20 0 1.22 1.24 1.26 1.28 1.30 Isink (mA) Vuv (V) Figure 13. PWM Saturation Voltage 5 Figure 14. Detecting UV Voltage 5 4 4 PG (V) 2 PG (V) 4.8 4.6 4.4 4.2 4.0 3 3 2 1 1 0 5.0 0 0.5 1.0 1.5 2.0 2.5 V5 (V) V10 (V) Figure 15. Detecting V5 Voltage for PG 0.4 Figure 16. High/low Threshold Voltage of Comp9 0.4 0.3 0.3 Vsat_PG (V) Vdis (V) 0.2 0.2 0.1 0.1 0.0 0.0 0 5 10 Isink (mA) 15 20 25 0 5 10 15 20 Isink (mA) Figure 17. PG Saturating Voltage Figure 18. Disable Saturation Voltage 9 KA3502 Typical Characteristics (Continued) 10 20 8 15 PWM Icc (mA) 6 (V) 4 10 2 5 REM 0 14 16 18 20 22 24 0 0 20 40 60 80 100 Vcc (V) Time (msec) Figure 19. Supply Current of Vcc Figure 20. 6 5 4 PG (V) 3 2 1 0 0.0 UV 0.2 0.4 0.6 0.8 1.0 Time (sec) Figure 21. PG Delay 10 KA3502 Mechanical Dimensions Package Dimensions in millimeters 20-DIP 11 KA3502 Ordering Information Product Number KA3502 Package 20-DIP Operating Temperature 0C ~ 70C 12 KA3502 13 KA3502 DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR INTERNATIONAL. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. www.fairchildsemi.com 9/25/00 0.0m 001 Stock#DSxxxxxxxx 2000 Fairchild Semiconductor International 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. |
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