View FAN7680_160544.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

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
(c)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=25C, 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=25C, 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 <500ms -T4(PGO Delay Risetime) : T4 10ms -T5(AC Loss to PGO Hold-Up Time) : T5 16ms -T6(Power Down Warning) : T6 1ms
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 FAN7680 provides a power good(PGO) signal for the +3.3V, +5V and +12V(Vcc) supply voltage rails and a separate power good input(PGI). An internal delay circuit is used to generate a 300ms power good delay. If voltages at PGI(+1.2V), VS33(+3.3V), VS5(+5V), and Vcc(+12V) rise above the undervoltage threshold, the open drain power good output(PGO) will go high after a delay of 300ms. When the PGI voltage or any of +3.3V, +5V, and +12V rails drops below the undervoltage threshold, the PGO signal will be disabled immediately.
Power Supply Remote On/Off(PSON) and Fault Protect Output(FPO)
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(PSON) is an active-low signal that turns on all of the main power rails including the +3.3V, +5V, and +12V power rails. When this signal is held high by the PC motherboard or left open circuited, the signal of the fault protect output(FPO) also goes high. Thus, the main power rails can not deliver power and are held at 0V. When the FPO 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 PSON 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 PSON input signal goes from high to low or low to high, the 38ms debounce block will be active to avoid that a glitch on the PSON input may disable/enable the FPO output. When the PSON is set low, the undervoltage function is disabled
11
FAN7680
during 75ms to avoid turn-on failure. At turn-off, there is an additional delay of 2.3ms from PSON to FPO. Power should be delivered to the rails only when the PSON signal is held at ground potential, thus the FPO becomes a low state after a debounce of 38ms. The FPO pin can be connected to +5V(or up to +15V) through a pull-up resistor.
Under Voltage Protection(UVP)
The FAN7680 provides undervoltage protection(UVP) for the +3.3V, +5V, and +12V power rails. When an undervoltage condition appears at one of the VS33(+3.3V), VS5(+5V), or Vcc(+12V) input pins for more than 73us, the PGO goes low and FPO output goes high. Also, this fault condition will be latched until the PSON 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 PSON, an internal UVP delay is 75ms. But at normal state an UVP delay time is a 73us 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 TTL or CMOS logic often malfunctions under UVP condition.
Over Voltage Protection(OVP)
The overvoltage protection(OVP) of the FAN7680 monitors +3.3V, +5V, and +12V(the +12V output is sensed via the Vcc pin). When an overvoltage condition appears at one of the +3.3V, +5V, or +12V input pins for more than 73us, the FPO output goes high and the PGO goes low. Also, this fault condition will be latched until the PSON 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 TTL and CMOS circuits are very vulnerable to overvoltage, it is becoming industry standard to provide overvoltage protection on all +3.3V, +5V, and +12V outputs. Therefore, not only the +3.3V and +5V rails for the logic circuits on the motherboard need to be protected, but also the +12V peripheral devices such as the hard disk, flopply disk, and CD-ROM players etc., need to be protected.
12
FAN7680
Mechanical Dimensions
Package Dimensions in millimeters
8-DIP
13
FAN7680
Mechanical Dimensions
Package Dimensions in millimeters
8-SOP
14
FAN7680
Ordering Information
Product Number FAN7680N FAN7680M Package 8DIP 8SOP Operating Temperature -40C ~ +125C
15
FAN7680
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 CORPORATION. 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 6/23/03 0.0m 001 Stock#DSxxxxxxxx 2003 Fairchild Semiconductor Corporation
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.

▲Up To Search▲

Price & Availability of FAN7680

	To Download FAN7680 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .