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FAN7685/FAN7686/FAN7687
PC Power Supply Output Monitoring IC
Features
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PC Power Supply Outputs Supervisory Circuitry
Few External Components
Over Voltage Protection for 3.3V, 5V and 12V Outputs
Under Voltage Protection for 3.3V, 5V and 12V Outputs
Over Current Protection for 3.3V, 5V and 12V Outputs
Dual Over Current Portection for 12V Outputs
(FAN7687)
Fault Protection Output With Open Drain Output
Open Drain Power Good Output
300ms Power Good Delay
38ms PSON On/Off Delay
73us Debounce
2.3ms PSON to FPO Turn Off Delay
Latch Function Controlled by PSON
Description
The FAN7685/FAN7686/FAN7687 is a complete output
supervisory circuitry intended for use in the secondary side
of the switched mode power supply. It provides overvoltage
protection (OVP), undervoltage protection(UVP), overcur-
rent protection (OCP), and power good signal generator to
monitor and control the outputs of the switching power sup-
ply system. Remote on/off(PSON) control and some preci-
sion protection features are also implemented.
It directly senses all the output rails for OVP, UVP, and OCP
without external divider resistors. As for output control,
power good output(PGO) and fault protection output(FPO)
are included. The FAN7685/FAN7686/FAN7687 offers a
simple and cost effective solution with minimum number of
external components and greatly reduces PCB board space
for power supply.
14DIP
Typical Application
• PC Switching Mode Power Supply
1
14SOP
1
Rev. 1.1.0
©2004 Fairchild Semiconductor Corporation
FAN7685/FAN7686/FAN7687
Internal Block Diagrams
Vcc
13
Vcc
REF.
Start-up
POR
3.6V
Vref
PSON
clr
Delay
2.3ms
CLK
Oscillator
Reset
CLK
VS12
10
VS5
12
VS33
11
(9)
UVP
L
L
H
Delay
75ms
CLK
R
R
L
Debounce
73us
R
L
S
Q
L
L
H
FPO
L
3
FPO
CLK
L
PWR
clr
L
PGI_O
OVP
L
L
L
Vref
3.6V
H
Q
L
L
L
PSON
L
Debounce
38ms
R
CLK
L
R
Vcc
150uA
3.6V
L
L
4
PSON
14
PGO
2
GND
IS33
9
(8)
H
IS5
8
L
UVP
H
L
L
L
8*Iref
8*Iref
8*Iref
H
H
(7)
Vcc
Iref
R
H
CLK
L
H
Short
Detector
when AC ON
IS12
5
Debounce
73us
H
Delay
clr 300ms
CLK
1.2V
Vref
PSON
6
1
FAN7685
(FAN7686)
RI
PGI
VCC12
13
Vcc
REF.
Start-up
POR
Power On Reset
3.6V
Vref
PSON
clr
Delay
2.3ms
CLK
Oscillator
Reset
CLK
R
L
L
Q
L
H
FPO
UVP
Block
VS12
10
VS5
12
UVP
L
3
FPO
L
H
Delay
75ms
CLK
R
L
Debounce
73us
R
L
S
CLK
clr
L
L
PGI_O
R
Vcc
150uA
3.6V
VS33
11
OVP
Block
OVP
L
PSON
L
Debounce
38ms
R
CLK
L
L
4
PSON
3.6V
H
14
PGO
2
GND
IS33
9
Q
L
L
L
IS5
8
OCP
COMPs
Vcc
Iref
H
H
L
L
H
Short
Detector
when AC ON
IS12
5
UVP
R
H
CLK
H
H
ISVCC12
7
8*Iref
L
L
L
Vref
PSON
Debounce
73us
1.2V
H
Delay
clr 300ms
CLK
6
1
RI
PGI
FAN7687
FAN7687A
2
FAN7685/FAN7686/FAN7687
Pin Assignments
PGI
1
GND
2
14
PGO
13
V
CC
PGI
1
GND
2
14
PGO
13
V
CC
PGI
GND
FPO
1
2
14
PGO
13
VCC12
F A N 7687
FAN7687A
F A N 7 685
F A N 7 686
FPO
3
PSON
4
IS12
5
RI
6
NC
7
12
VS5
11
VS33
10
VS12
9
IS33
8
IS5
FPO
3
PSON
4
IS12
5
RI
6
IS5
7
12
VS5
11
VS33
10
NC
9
VS12
8
IS33
3
12
VS5
11
VS33
10
VS12
9
IS33
8
IS5
PSON
4
IS12
RI
5
6
ISVCC12
7
Pin Definitions
Pin Number
1
2
3
4
5
6
7
Pin Name
PGI
GND
FPO
PSON
IS12
RI
NC
IS5*
ISVCC12**
8
9
10
11
12
13
14
IS5
IS33*
IS33
VS12*
VS12
NC*
VS33
VS5
Vcc
VCC12**
PGO
I
I
I
I
O
I
I
I
I
I
I
I
I/O
I
-
O
I
I
O
Power Good Input
Ground
Fault Protection Output, Open Drain Output
Remote On/Off Control Input
12V Over Current Protection
Reference Current Setting Resistor
No Connection
(FAN7685)
5V Over Current Protection
(FAN7686)
12V-II Over Current Protection
(FAN7687)
5V Over Current Protection
(FAN7685/7)
3.3V Over Current Protection
(FAN7686)
3.3V Over Current Protection
(FAN7685/7)
12V Output Over/Under Voltage Protection
(FAN7686)
12V Output Over/Under Voltage Protection
(FAN7685/7)
No Connection
(FAN7686)
3.3V Output Over/Under Voltage Protection
5V Output Over/Under Voltage Protection
Supply Voltage
(FAN7675/6)
Supply Voltage & 12V-II OV/UV Protectioin
(FAN7687)
Power Good Output, Open Drain Output
Pin Function Description
Notes :
* : FAN7686 Pin Definitions
** : FAN7687/FAN7687A Pin Definitions
3
FAN7685/FAN7686/FAN7687
Absolute Maximum Ratings
Parameter
Supply Voltage
Input Voltage
Symbol
V
CC
, VCC12
V
PSON
, VS5, VS33, V
PGI
,
IS5, IS33
VS12, IS12, ISVCC12
Output Voltage
Operating Temperature
Storage Temperature
Power Dissipation
V
PGO
V
FPO
Topr
Tstg
P
D
Value
16
8
16
8
16
-40 ~ 125
-55 ~ 150
1
V
°C
°C
W
Unit
V
V
*Note : Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device.
Recommended Operating Conditions
Characteristic
Supply Voltage
Input Voltage
V
CC
, VCC12
V
PSON
, VS5, VS33, V
PGI
, IS5,
IS33
VS12, IS12, ISVCC12
Output Voltage
Output Sink Current
Supply Voltage Rising Time, See Note1
Output Current for RI
Note
1. V
CC
slew rate must be less than 14V/ms.
Min.
4
-
-
-
-
-
-
1
12.5
Typ.
Max.
15
Unit
V
V
V
V
mA
mA
ms
uA
-
-
-
-
-
-
-
7
15
7
15
30
10
62.5
V
PGO
V
FPO
I
FPO
I
PGO
tr
I
O(RI)
4
FAN7685/FAN7686/FAN7687
Electrical Characteristics
(V
CC
= 5V, Ta=25°C, unless otherwise specified)
Over Voltage Protection, Under Voltage Protection and FPO
Parameter
VS33
VS5
VS12,
VCC12
VS33
VS5
VS12,
VCC12
Ratio of Current Sense Sink Current to
Current Sense Setting Pin(RI) Source
Current
Offset Voltage of OCP Comparator
Leakage Current(FPO)
Low Level Output Voltage(FPO)
PGI and PGO
Input Threshold Voltage(PGI)
Leakage Current(PGO)
Low Level Output Voltage(PGO)
PSON Control
Input Pull-up Current
High-Level Input Voltage
Low-Level Input Voltage
Total Device
Supply Current
Switching Characteristics
Debounce Time(PSON)
Noise Debounce Time
PGO Delay Time(PGI to PGO)
Internal UVP Delay Time
I
CC
V
PSON
= 5V
-
25
50
200
FPO goes low and
every time PGI > 1.2
FPO goes low and
everytime PGI<1.2
51
200
-
38
73
300
75
300
1
51
100
410
102
410
mA
I
PSON
V
IHPS
V
ILPS
V
PSON
= 0V
-
2.4
-
150
-
-
-
-
1.2
uA
V
V
V
PGI
I
LKG2
V
OL2
V
PGO
= 5V
I
PGO
=10mA
1.16
-
-
1.20
-
-
1.24
5
0.4
V
uA
V
Test Condition
FAN7687A
Min.
3.9
3.77
5.8
Typ.
4.1
6.1
13.8
Max.
4.3
4.06
6.4
6.16
14.3
14.79
14.5
Unit
Over Voltage Threshold
FAN7687A
5.71
13.3
(VS12)
V
FAN7687A
13.71
13.42
2.55
2.69
4.3
9.3
2.88
4.1
4.37
8.8
10.5
10.21
7.6
-5
-
-
-
8
-
-
-
-
FAN7687A
(VCC12)
2.83
3.02
4.5
4.58
9.8
11.0
10.71
8.4
5
5
0.3
0.7
mV
uA
V
V
FAN7687A
Under Voltage Threshold
FAN7687A
FAN7687A
(VS12)
FAN7687A
(VCC12)
Iref
V
offset
I
LKGI
V
OLI
Resistor at RI=30kΩ,
0.1% Resistor
V
PSON
=0V
V
FPO
= 5V
I
FPO
=10mA
I
FPO
=30mA
t
b1
t
b2*
t
d1
t
d2
t
d4*
ms
us
ms
ms
ms
ms
PSON off to FPO Delay Time
t
d3
t
b1
+1.6 t
b1
+2.3 t
b1
+3.2
* : These parameters although guaranteed over the recommended operating conditions, are not 100% tested in production.
5
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