FAN7680M

www.fairchildsemi.com FAN7680 PC Power Supply Outputs Monitoring IC Features • PC Power Supply Output Monitor Circuitry • Few External Components • Over Voltage Protection for 3.3V, 5V and 12V(Vcc) Outputs • Under Voltage Protection for 3.3V, 5V and 12V(Vcc) Outputs with Delay Time • Fault Protection Output with Open Drain Output • Open Drain Power Good Output • 300ms Power Good Delay • 38ms PSON On/Off Debounce • 73us Debounce • 2.3ms PSON to FPO Turn Off Delay • Latch Function Controlled by PSON and Protection Inputs Description The FAN7680 is a complete output supervisory circuitry intended for use in the secondary side of a switched mode power supply. It provides over voltage protection (OVP), under voltage protection (UVP), fault protection output (FPO), remote On/Off (PSON), latch, internal delay circuits and power good signal generator to monitor and control the output of the switching power supply system. As for output control, power good output(PGO) and fault protection output(FPO) are included. It directly senses all the output rails for OVP and UVP without external dividers. The FAN7680 offers a simple and cost effective solution with minimum number of external components and greatly reduces PCB board space for power supply. 8-DIP Typical Application • PC Power Supply 8-SOP 1 1 OVP The FAN7680 has OVP functions for +3.3V, +5V, +12V(Vcc) outputs. This block is made up of three comparators with two inputs and resistor dividers. One input of a comparator is connected to a reference voltage and another input is connected to a resistor divider. FPO The FPO(Fault Protection Output) is a signal which indicates the system fault condition according to protection signals. When a fault state is occured, the FPO signal becomes high and the PGO signal becomes low and the main power is to be turned off. Normal State; "Low" Fault State; "High" UVP The FAN7680 also has UVP functions for +3.3V, +5V, +12V(Vcc) outputs. This block is made up of three comparators with two inputs and resistor dividers. One input of a comparator is connected to a reference voltage and another input is connected to a resistor divider. PGO The power good signal generator provides a signal according to output voltage conditions of a power supply for safe operation of a secondary system. The power good output should be low state before the output voltage is out of regulation at turn-off of the input power switch. Normal State ; "High" Fault State ; "Low" PSON The remote on/off(PSON) section is for controlling the SMPS externally. When a high signal is applied to the PSON input, the FPO signal becomes a high state and all secondary outputs are grounded. The remote on/off signal is transferred with some on/off debounce time. Rev. 1.0.0 ©2003 Fairchild Semiconductor Corporation FAN7680 Internal Block Diagram PSON clr Delay 2.3ms Vcc REF. Start-up POR 3.6V Vref CLK Oscillator Reset CLK VCC 7 VS5 6 VS33 5 L R UVP L H Delay 75ms CLK L L Q L H 3 FPO R L Debounce 73us R L S CLK clr R PGI_O L Vcc 150uA 3.6V OVP L PSON L Debounce 38ms R CLK L L 4 PSON Vref 3.6V UVP L H PGI_O Vref L PSON L H CLK Q H L L L H 8 PGO GND R CLK PGI 1 Debounce 73us H clr Delay 300ms 2 Typical Applicatin Circuit 5Vsb PGI PGO +12V 1 PGI 2 GND 3 FPO PGO VCC VS5 VS33 8 7 6 5 5Vsb +5V +3.3V PSON 4 PSON FAN7680 2 FAN7680 Pin Assignments PGI GND FPO 1 2 3 YWW 8 7 6 5 PGO VCC VS5 VS33 FAN7680 PSON 4 YWW :Work Week Code Pin Definitions Pin Number 1 2 3 4 5 6 7 8 Pin Name PGI GND FPO PSON VS33 VS5 VCC PGO I/O I O I I I I Pin Function Description Power Good Input Ground Low Active Fault Protection Output, Open Drain Output Stage Remote On/Off Control Input 3.3V Output Voltage Input 5V Output Voltage Input Supply Voltage and 12V Output Voltage Input Power Good Output Signal O 3 FAN7680 Absolute Maximum Ratings Parameter Supply Voltage Supply Current Input Voltage Output Voltage Operating Temperature Storage Temperature Power Dissipation (Note2,3) Symbol VCC ICC VPSON, VS5 VS33, VPGI VPGO VFPO TO TS PD Value 16 1 8 8 16 -40 ~ +125 -65 ~ +150 1 Unit V mA V V °C °C W Recommended Operating Conditions Characteristic Supply Voltage Input Voltage Output Voltage Output Sink Current Supply Voltage Rising Time Symbol VCC VPSON , VS5, VS33, VPGI VPGO VFPO IFPO IPGO tr Note1 (Note2,3) Test Condition Min. 4 Typ. Max. 15 7 7 15 30 10 Unit V V V V mA mA ms 1 4 FAN7680 Electrical Characteristics (VCC = 5V, Ta=25°C, unless otherwise specified) Over Voltage Protection, Under Voltage Protection and FPO Characteristic Over Voltage Threshold Symbol VS33OV VS5OV 12V(VCC)OV VS33UV Under Voltage Threshold Leakage Current(FPO) Low Level Output Voltage(FPO) VS5UV 12V(VCC)UV ILKG1 VOLI VFPO = 5V Isink=10mA Isink=30mA Test Condition Min. 3.9 5.8 13.3 2.55 4.1 8.8 Typ. 4.1 6.1 13.8 2.69 4.3 9.3 Max. 4.3 6.4 14.3 2.83 4.5 9.8 5 0.3 0.7 uA V V V Unit PGI and PGO Characteristic Input Threshold Voltage(PGI) Leakage Current(PGO) Low Level Output Voltage(PGO) Symbol VPGI ILKG2 VOL2 VPGO = 5V Isink=10mA Test Condition Min. 1.16 Typ. 1.20 Max. 1.24 5 0.4 Unit V uA V PSON Control Characteristic Input Pull-up Current High-Level Input Voltage Low-Level Input Voltage Symbol Test Condition VPSON = 0V Min. 2.4 Typ. 150 Max. 1.2 Unit uA V V Total Device Characteristic Supply Current Symbol ICC Test Condition VPSON = 5V Min. Typ. Max. 1 Unit mA Timing Characteristics (VCC=5V, Ta=25°C, unless otherwise specified) Characteristic Debounce Time(PSON) Noise Debounce Time PGO Delay Time(PGI to PGO) Internal UVP Delay Time PSON Off to FPO Delay Time Symbol Test Condition Note 4 FPO goes low and every time PGI > 1.20 Min. 25 50 200 51 tb1+1.6 Typ. 38 73 300 75 tb1+2.3 Max. 51 100 410 102 tb1+3.2 Unit ms us ms ms ms tb1 tb2 td1 td2 td3 Note 1. VCC slew rate must be less than 14V/ms. 2. All voltages are measured with respect to the ground pin, unless otherwise specified. 3.The Absolute Maximum Ratings indicate the limits that if exceed, damage to the device may occur. Recommended Operating Conditions indicate conditions in which the device is functional, but do not guarantee specific performance limits. 4. This parameter, although guaranteed over the Timing Characteristics, is not 100% tested in production. 5 FAN7680 Typical Characteristics 6 5 4 3 2 1 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 PSON (V) PGO (V) FPO (V) 6 5 4 3 2 1 0 1.14 1.16 1.18 1.20 PGI (V) 1.22 1.24 Figure 1. PSON Threshold Voltage Figure 2. PGI Threshold Voltage 6 5 4 FPO (V) 3 2 1 0 2.83 2.79 2.75 2.71 2.67 2.63 2.59 2.55 VS33 (V) FPO (V) 6 5 4 3 2 1 0 3.90 3.94 3.98 4.02 4.06 4.10 4.14 4.18 4.22 4.26 4.30 VS33 (V) Figure 3. +3.3V UVP Voltage Figure 4. +3.3V OVP Voltage 6 5 4 FPO (V) 3 2 1 0 4.50 4.45 4.40 4.36 4.31 4.26 4.21 4.16 4.12 VS5 (V) FPO (V) 6 5 4 3 2 1 0 5.80 5.88 5.96 6.04 6.12 6.20 6.28 6.36 VS5 (V) Figure 5. +5V UVP Voltage Figure 6. +5V OVP Voltage 6 FAN7680 Typical Characteristics 6 5 4 FPO (V) 3 2 1 0 9.80 9.60 9.40 9.20 9.00 8.80 Vcc (V) FPO (V) 6 5 4 3 2 1 0 13.30 13.50 13.70 13.90 Vcc (V) 14.10 14.30 14.50 Figure 7. +12V UVP Voltage Figure 8. +12V OVP Voltage 7 FAN7680 Timing Chart 1) AC Input ON/OFF - Normal State VCC AC Input Enable POR PSON FPO tb1 UVP Threshold AC Input Disable PGI OUT PGO tb2+td1 2) PSON ON/OFF - Normal State PSON FPO td3 tb1 PGI UVP Threshold OUT tb1+tb2 PGO tb2+td1 - Vcc : Supply Voltage - POR : Power On Reset - PSON : Power Supply On/Off - FPO : Fault Protection Output - PGI : Power Good Input - OUT : Output Voltages - PGO : Power Goood Output 8 FAN7680 3) Under Voltage at Normal State PSON Latch FPO tb2 tb1 UVP Threshold PGI UVP Threshold OUT PGO tb2+td1 4) Under Voltage at AC Input ON VCC AC Input Enable POR PSON Latch FPO tb1 tb2+td2 PGI PGI Threshold UVP Threshold OUT PGO tb2+td1 9 FAN7680 5) Under Voltage at PSON ON/OFF PSON Latch FPO td3 tb1 tb2+td2 PGI PGI Threshold UVP Threshold OUT tb1+tb2 PGO tb2+td1 6) Over Voltage at PSON ON/OFF PSON Latch FPO tb2 tb1 PGI OVP Threshold UVP Threshold OUT PGO tb2+td1 10 FAN7680 Application Information Power Good(PGO) and Power Good Delay A PC power supply is commonly designed to provide the motherboard with a power good signal, which is defined by the computer manufactures. If the +3.3V, +5V, and +12V outputs are above the undervoltage threshold limit, the PC power supply makes the power good signal high after some delay. At this time the power supply should be able to provide enough power to assure continuous operation within the specification. Conversely, when one of the +3.3V, +5V, or +12V outputs falls below the undervoltage threshold or rise above the overvoltage threshold, or when main power has been turned off for a sufficiently long time so that power supply operation is no longer assured, a PGO signal will be a low state. The AC input, power good(PGO), remote on/off(PSON), and +3.3V/+5V/+12V supply rails are shown in figure 1. T1 VAC PSON +12VDC +5VDC +3.3VDC PGO 95% 10% T5 T3 T2 T4 T5 Figure 1. Timing Diagram Although there is no requirement for specific timing parameters, the following signal timings are recommended : -T1(Power On Time) : T1 < 500ms -T2(Rise Time) : 0.1ms ≤ T2 ≤ 20ms -T3(PGO Delay) : 100ms < T3