FAN7680. PC Power Supply Outputs Monitoring IC. Features. Description. Typical Application. FPO OVP UVP PGO PSON

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1 PC Power Supply Outputs Monitoring IC Features PC Power Supply Output Monitor Circuitry Few External Components Over Voltage Protection for.v, V and V(Vcc) Outputs Under Voltage Protection for.v, V and V(Vcc) Outputs with Delay Time Fault Protection Output with Open Drain Output Open Drain Power Good Output 00ms Power Good Delay 8ms On/Off Debounce 7us Debounce.ms to Turn Off Delay atch Function Controlled by and Protection Inputs Description The FAN780 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 (), fault protection output (), remote On/Off (), 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() and fault protection output() are included. It directly senses all the output rails for OVP and without external dividers. The FAN780 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 OVP The FAN780 has OVP functions for +.V, +V, +V(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. The FAN780 also has functions for +.V, +V, +V(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. The remote on/off() section is for controlling the SMPS externally. When a high signal is applied to the input, the signal becomes a high state and all secondary outputs are grounded. The remote on/off signal is transferred with some on/off debounce time. The (Fault Protection Output) is a signal which indicates the system fault condition according to protection signals. When a fault state is occured, the signal becomes high and the signal becomes low and the main power is to be turned off. Normal State; "ow" Fault State; "High" 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 ; "ow" Rev Fairchild Semiconductor Corporation

2 Internal Block Diagram Vcc Start-up REF. POR.V Vref Oscillator CK clr Delay.ms CK VCC VS VS 7 Reset Delay 7ms clr H CK R R S Q Debounce 7us CK R H _O R Vcc 0uA OVP.V Debounce 8ms Vref R CK H _O H R CK Debounce 7us H clr CK Delay 00ms H Q.V H 8 GND Vref Typical Applicatin Circuit Vsb +V 8 GND VCC 7 Vsb VS +V VS +.V FAN780

3 Pin Assignments GND FAN780 YWW 8 7 VCC VS VS YWW :Work Week Code Pin Definitions Pin Number Pin Name I/O Pin Function Description I Power Good Input GND - Ground O ow Active Fault Protection Output, Open Drain Output Stage I Remote On/Off Control Input VS I.V Output Voltage Input VS I V Output Voltage Input 7 VCC I Supply Voltage and V Output Voltage Input 8 O Power Good Output Signal

4 Absolute Maximum Ratings (Note,) Parameter Symbol Value Unit Supply Voltage VCC V Supply Current ICC ma Input Voltage V, VS VS, V 8 V Output Voltage V 8 V V Operating Temperature TO -0 ~ + C Storage Temperature TS - ~ +0 C Power Dissipation PD W Recommended Operating Conditions (Note,) Characteristic Symbol Test Condition Min. Typ. Max. Unit Supply Voltage VCC V Input Voltage V, VS, VS, V 7 V Output Voltage V 7 V V V Output Sink Current I 0 ma I 0 ma Supply Voltage Rising Time tr Note ms

5 Electrical Characteristics (VCC = V, Ta= C, unless otherwise specified) Over Voltage Protection, Under Voltage Protection and Characteristic Symbol Test Condition Min. Typ. Max. Unit Over Voltage and Control Total Device Timing Characteristics (VCC=V, Ta= C, unless otherwise specified) VSOV.9.. VSOV.8.. V(VCC)OV..8. VSUV..9.8 Under Voltage VSUV... V V(VCC)UV eakage Current() IKG V = V - - ua ow evel Output Voltage() VOI Isink=0mA Isink=0mA V Characteristic Symbol Test Condition Min. Typ. Max. Unit Input Voltage() V..0. V eakage Current() IKG V = V - - ua ow evel Output Voltage() VO Isink=0mA V Characteristic Symbol Test Condition Min. Typ. Max. Unit Input Pull-up Current V = 0V ua High-evel Input Voltage. - - V ow-evel Input Voltage - -. V Characteristic Symbol Test Condition Min. Typ. Max. Unit Supply Current ICC V = V - - ma Characteristic Symbol Test Condition Min. Typ. Max. Unit Debounce Time() tb 8 ms Noise Debounce Time tb Note us Delay Time( to ) td ms Internal Delay Time td goes low and every time > ms Off to Delay Time td tb+. tb+. tb+. ms Note. VCC slew rate must be less than V/ms.. All voltages are measured with respect to the ground pin, unless otherwise specified..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.. This parameter, although guaranteed over the Timing Characteristics, is not 00% tested in production. V

6 Typical Characteristics (V) (V) (V) (V) Figure. Voltage Figure. Voltage (V) (V) VS (V) VS (V) Figure. +.V Voltage Figure. +.V OVP Voltage (V) (V) VS (V) VS (V) Figure. +V Voltage Figure. +V OVP Voltage

7 Typical Characteristics (V) (V) Vcc (V) Vcc (V) Figure 7. +V Voltage Figure 8. +V OVP Voltage 7

8 Timing Chart ) AC Input ON/OFF - Normal State VCC AC Input Enable POR t b AC Input Disable OUT t b +t d ) ON/OFF - Normal State t d t b OUT t b +t b t b +t d - Vcc : Supply Voltage - POR : Power On Reset - : Power Supply On/Off - : Fault Protection Output - : Power Good Input - OUT : Output Voltages - : Power Goood Output 8

9 ) Under Voltage at Normal State atch t b t b OUT t b +t d ) Under Voltage at AC Input ON VCC AC Input Enable POR atch t b t b +t d OUT t b +t d 9

10 ) Under Voltage at ON/OFF atch t d t b t b +t d OUT t b +t b t b +t d ) Over Voltage at ON/OFF atch t b t b OUT OVP t b +t d 0

11 Application Information Power Good() 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 +.V, +V, and +V 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 +.V, +V, or +V 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 signal will be a low state. The AC input, power good(), remote on/off(), and +.V/+V/+V supply rails are shown in figure. T T VAC +VDC +VDC +.VDC 9% 0% Figure. Timing Diagram T T T T Although there is no requirement for specific timing parameters, the following signal timings are recommended : -T(Power On Time) : T < 00ms -T(Rise Time) : 0.ms T 0ms -T( Delay) : 00ms < T <00ms -T( Delay Risetime) : T 0ms -T(AC oss to Hold-Up Time) : T ms -T(Power Down Warning) : T ms Furthermore, motherboards should be designed to comply with the above recommended timing range. If timings other than these are implemented or required, that information should be clearly specified. The FAN780 provides a power good() signal for the +.V, +V and +V(Vcc) supply voltage rails and a separate power good input(). An internal delay circuit is used to generate a 00ms power good delay. If voltages at (+.V), VS(+.V), VS(+V), and Vcc(+V) rise above the undervoltage threshold, the open drain power good output() will go high after a delay of 00ms. When the voltage or any of +.V, +V, and +V rails drops below the undervoltage threshold, the signal will be disabled immediately. Power Supply Remote On/Off() and Fault Protect Output() Since the latest personal computer generation focuses on easy turn on and power saving functions, a PC power supply will require two characteristics. One is a dc power supply remote on/off function; the other is standby voltage to achieve very low power consumption of the PC power supply. Thus, the main power needs to be shut down. The power supply remote on/off() is an active-low signal that turns on all of the main power rails including the +.V, +V, and +V power rails. When this signal is held high by the PC motherboard or left open circuited, the signal of the fault protect output() also goes high. Thus, the main power rails can not deliver power and are held at 0V. When the signal is held high due to an fault condition, the fault status will be latched and the outputs of the main power rails can not deliver power and are held at 0V. Toggling the input signal from low to high will reset the fault protection latch. During this fault condition only the standby power is not affected. When the input signal goes from high to low or low to high, the 8ms debounce block will be active to avoid that a glitch on the input may disable/enable the output. When the is set low, the undervoltage function is disabled

12 during 7ms to avoid turn-on failure. At turn-off, there is an additional delay of.ms from to. Power should be delivered to the rails only when the signal is held at ground potential, thus the becomes a low state after a debounce of 8ms. The pin can be connected to +V(or up to +V) through a pull-up resistor. Under Voltage Protection() The FAN780 provides undervoltage protection() for the +.V, +V, and +V power rails. When an undervoltage condition appears at one of the VS(+.V), VS(+V), or Vcc(+V) input pins for more than 7us, the goes low and output goes high. Also, this fault condition will be latched until the is toggled from low to high or the Vcc falls below a minimum operating voltage. When the power supply is turned on by the AC input or, an internal delay is 7ms. But at normal state an delay time is a 7us debounce time. The need for undervoltage protection is often overlooked in off-line switching power supply system design. But it is very important in battery powered or hand-held equipment since the TT or CMOS logic often malfunctions under condition. Over Voltage Protection(OVP) The overvoltage protection(ovp) of the FAN780 monitors +.V, +V, and +V(the +V output is sensed via the Vcc pin). When an overvoltage condition appears at one of the +.V, +V, or +V input pins for more than 7us, the output goes high and the goes low. Also, this fault condition will be latched until the is toggled from low to high or Vcc drops below a minimum operating voltage. During fault conditions, most power supplies have the potential to deliver higher output voltages than those normally specified or required. In unprotected equipment, it is possible for output voltages to be high enough to cause internal or external damage to the system. To protect the system under these abnormal conditions, it is common practice to provide overvoltage protection within the power supply. Because TT and CMOS circuits are very vulnerable to overvoltage, it is becoming industry standard to provide overvoltage protection on all +.V, +V, and +V outputs. Therefore, not only the +.V and +V rails for the logic circuits on the motherboard need to be protected, but also the +V peripheral devices such as the hard disk, flopply disk, and CD-ROM players etc., need to be protected.

13 Mechanical Dimensions Package Dimensions in millimeters 8-DIP

14 Mechanical Dimensions Package Dimensions in millimeters 8-SOP

15 Ordering Information Product Number Package Operating Temperature FAN780N 8DIP -0 C ~ + C FAN780M 8SOP

16 DISCAIMER FAIRCHID SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE REIABIITY, FUNCTION OR DESIGN. FAIRCHID DOES NOT ASSUME ANY IABIITY ARISING OUT OF THE APPICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY ICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. IFE SUPPORT POICY FAIRCHID S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICA COMPONENTS IN IFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVA OF THE PRESIDENT OF FAIRCHID SEMICONDUCTOR CORPORATION. As used herein:. ife 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.. 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. //0 0.0m 00 Stock#DSxxxxxxxx 00 Fairchild Semiconductor Corporation

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PC POWER SUPPLY SUPERVISOR

` HY510N PC POWER SUPPLY SUPERVISOR Data Sheet REV. 1.30 September 21, 2004 The information in this document is subject to change without notice. 1 11 TEL:886-2-23775117 FAX:886-2-23773189 Email:salesdep@hawyang.com.tw