FAIRCHILD SG6108DZ

Product Specification
SG6108
Power Supply Supervisor + PWM
FEATURES
„
„
„
„
„
„
„
„
„
„
„
„
„
„
„
„
DESCRIPTION
PC half-bridge (or 494) power supply supervisor +
PWM
Highly Integrated and Few external components
required
Over voltage protection 3.3V/5V/12V (two 12V)
Under voltage protection 3.3V/5V/12V (two 12V)
Under voltage protection for –12V and/or –5V
Over current protection 3.3V/5V/12V (two 12V)
Over power protection
Short circuit protection
Power-down warning circuitry
Power good circuitry
Delay time for PSON and PG signals
Remote ON/OFF function
On-Chip oscillator and Error amplifier
Latching PWM for cycle-by-cycle switching
Soft-start
Maximum 48% duty cycle
The SG6108 controller is designed for desktop PC
switching mode power supplies. It provides everything
necessary to monitor and control the output of the power
supply. Remote ON/OFF control, power good circuitry,
over-voltage protection, over-power protection, and
over-current protection are all included. The SG6108
directly senses all the output rails for over voltage
conditions without requiring external dividers. An
innovative AC-signal sampling circuit provides an
adequate power-down warning signal for PG. A built-in
timer generates accurate timing for the control circuit.
Cycle-by-cycle PWM switching protects the power
transformer from saturation and ensures a rapid response
for short-circuit protection. This greatly reduces the stress
on the power transistors. The SG6108 utilizes a minimum
number of external components while including all the
functions needed for push-pull and/or half-bridge
topologies. This decreases production costs and PCB
space while increasing the power supply’s MTBF.
APPLICATIONS
Switching mode power supplies for computers such
as ATX, NLX, and SFX (micro-ATX).
TYPICAL APPLICATION
+
12V
-12V
+
+
12V
+
5V
+
3.3V
+
+
+
Main Transformer
SG6108
UVAC
IS12
Vcc
IS33
IS5
5Vsb
V33
Pok
Pson
PG
Pson
OP1
V5
V12
VS12B
NVP
-12V
-5V
RI
GND
Vdd
IN
5V
12V
COMP
OP2
OPP
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-1-
SS
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
MARKING DIAGRAMS
PIN CONFIGURATION
20
1
20
VCC
V33
2
19
RI
V5
3
18
SS
OPP
4
17
IN
UVAC
5
16
COMP
NVP
6
15
GND
VS12
7
14
IS33
OP2
8
13
IS5
OP1
9
12
IS12
PG
10
11
VS12B
PSON
SG6108TP
XXXXXXXXYWWV
1
T : D = DIP
P : Z = Lead Free
Null=regular package
XXXXXXXX: Wafer Lot
Y: Year; WW: Week
V: Assembly Location
ORDERING INFORMATION
Part Number
Pb-Free
SG6108DZ
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
Package
20-Pin DIP
-2-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
PIN DESCRIPTIONS
Name
Pin
Type
Function
PSON
1
Logic Input
Remote On/Off logic input for the CPU or the controller. Turns the PWM output on/off following a 45
msec / 16 msec delay.
PSON = 0 means that the main SMPS is operational.
PSON =1 means that the main SMPS is off and the latch is reset.
V33
2
Analog Input
3.3V over-voltage/under-voltage control sense input.
V5
3
Analog Input
5V over-voltage/under-voltage control sense input.
OPP
4
Analog Input
Over-power sense input. This pin is connected to the driver transformer or the output of the current
transformer. When not in use, this pin should be grounded.
UVAC
5
Analog Input
AC fail-detection. This detects main AC voltage under-voltage and/or failure.
NVP
6
Analog Input
The protection input for negative outputs, such as –12V and/or –5V. Trip voltage = 2.1V.
VS12
7
Analog Input
12V over-voltage/under-voltage control sense input.
OP2/OP1
8/9
Analog Output
The totem-pole output drivers of a push-pull PWM. The outputs are enabled (low) only when the
NAND gate inputs are high. The maximum duty cycle on an output (OP1 or OP2) is 48%.
PG
10
Logic Output
Power Good logic output, 0 or 1 (open-collector). PG = 1 means that the power is good for operation.
The PG delay is 300 msec.
VS12B
11
Analog Input
Second 12V over-voltage/under-voltage control sense input.
IS12
12
Analog Input
12V over current protection sense input. The sink current = 8 x IRI
IS5
13
Analog Input
5V over current protection sense input. The sink current = 8 x IRI
IS33
14
Analog Input
3.3V over current protection sense input. The sink current = 8 x IRI
GND
15
Supply
Ground.
COMP
16
Analog Output
The error amplifier output and the input of the PWM comparator.
IN
17
Analog Input
The negative input of the error amplifier. The positive input of the error amplifier is a 2.5V reference
voltage.
SS
18
Analog Input
Soft-start. This can be set through the external capacitor. The current source output at this pin is 8uA
and the voltage is clamped at 2.5V.
RI
19
Program.
Analog Input
This is connected to the external resistor to provide a reference setting. It determines the PWM
frequency, and also the OCP current setting. Setting RI = 75kΩ will result in a PWM frequency of
65kHz. Do not attach a capacitor to this pin. For OCP current settings please refer to the Over Current
Protection section on page 13.
VCC
20
Supply
Supply voltage. 4.5V ~ 5.5V. It is connected to the 5V-standby.
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-3-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
BLOCK DIAGRAM
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-4-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
TIMING DIAGRAM
VCC
PSON
3.3V,5V,12V
tpson(on)
tuvp
NVP
tnvp
tpson(off)
SS(on/off)
tpsoff
PG
tPG
VCC
PSON
Voltage < VUVAC
UVAC
tOPP
OPP
SS(on/off)
PG
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-5-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
VCC, MAX
DC Supply Voltage at Pin 20
6
V
IOUT
Input Current at PG,FB Pins
30
mA
VPIN, MAX
Unit
OP1, OP2, VS12, VS12B, IS12
-0.3 to 16
V
OPP, UVAC, RI, SS, PG, IN, COMP, FB, NVP, IS5, V33, V5, PSON
-0.3 to 7
V
PD,25℃
Power Dissipation (TA=25℃)
1.5
W
PD,90℃
Power Dissipation (TA=90℃)
0.5
W
TSTG
Storage Temperature Range
-55 to +150
℃
RθJA
Thermal Resistance, Junction-To-Case
28.58
℃/W
TJ,MAX
Operating Junction Temperature
150
℃
TA,MAX
Operating Ambient Temperature
-20 to +85
℃
TL
Lead Temperature (Wave soldering or IR, 10seconds)
260
℃
ESD Capability, HBM model
3.0
KV
ESD Capability, Machine model
200
V
* All voltage values, except the differential voltage, are given with respect to the network ground terminal.
* Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Value
Unit
VCC
DC Supply Voltage
4.5 to 5.5
V
TA
Operating Ambient Temperature
-20 to +85
℃
* For proper operation
Electrical Characteristics (VCC=5V, TA = 25°C,RI=75Kohm,unless noted)
VCC Section
Symbol
Parameter
Test Condition
ICC1
Total Supply Current
PSON=Low,
OP1/OP2 1000pF
ICC2
Total Supply Current
PSON=High,
OP1/OP2 1000pF
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-6-
Min.
Typ.
5
Max.
Unit
10
mA
10
mA
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
Protection Section
Symbol
Parameter
VOVP1
Over-Voltage Protection 3.3V
Test Condition
VOVP2
Over-Voltage Protection 5V
5.8
6.1
6.5
V
VOVP3
Over-Voltage Protection VS12,VS12B
13.75
14.05
14.35
V
VUVP1
Under-Voltage Protection 3.3V
2.0
2.6
2.8
V
VUVP2
Under-Voltage Protection 5V
3.0
3.6
3.9
V
VUVP3
Under-Voltage Protection VS12,VS12B
6.0
7.2
8.0
V
VUVS1
Under-Voltage Sense 3.3V for PG Low
2.5
2.8
3.0
V
VUVS2
Under-Voltage Sense 5V for PG Low
4.0
4.3
4.5
V
VUVS3
Under-Voltage Sense VS12,VS12B for PG Low
VOPP* 1
Over-Power Protection (With TOPP delay time)
VUVAC = 1.5V
Min.
Typ.
Max.
Unit
3.9
4.1
4.3
V
9.4
10.1
10.4
V
2.23
2.3
2.37
V
VOPPH
Over-Power Protection (Without delay time)
3.0
3.2
3.4
V
VX
Disable Under Voltage / Over Power Protection
threshold
0.2
0.3
0.4
V
VNVP
Negative Voltage Protection: Voltage Level
2.0
2.1
2.2
V
INVP
Negative Voltage Protection: Source Current
57
64
72
uA
TUVEDA
Under Voltage Enable Delay Time
VS12/B = 0.8V
10
17
22
mS
TUVEDB
Under Voltage Enable Delay Time
VS12/B = 5V
22
30
40
mS
TOVP
Timing for Over-Voltage Protection
0.37
0.7
1.35
mS
TUVP
Timing for Under-Voltage Protection
1.2
2.7
4.2
mS
TUVS
Timing for Under-Voltage Sense (PG Low)
0.9
1.6
2.2
mS
TOPP
Timing for Over-Power-Protection
4
6
8
mS
TNVP
Timing for Negative Voltage Protection
3.3
7
10.2
mS
TOCP
Timing for Over-Current Protection
15
20
25
mS
TOCP(EN)
Timing for Over-Current Protection Function Enable
SS go Hi, VS12/B=0.8V
10
17
22
SS go Hi, VS12/B =5V
22
30
40
VOFFSET
OCP Comparator Input Offset Voltage
-5
IREF
Ratio of IS33, IS5, IS12 to RI Current Setting
7.6
5
8
mS
mV
8.4
ILK33
V33 Leakage Current
V33 = 3.3V
50
uA
ILK5
V5 Leakage Current
V5= 5V
50
uA
50
uA
ILK12AB
VS12, VS12B Leakage Current
VS12 =12V
VS12B = 12V
Note *1: VOPP = (2/3) x VOPP + (1/3) x VUVAC ;
Power Good Section
Symbol
Parameter
TPG
Timing for PG Delay
TUVAC
Timing for PG Fail
VUVAC
UVAC Voltage Sense for PG
VUVAC(DIS)
Disable UVP,NVP,OCP Voltage
TUVAC(DIS)
Timing for Disable UVP,NVP,OCP
TUVAC(EN)
Timing for Enable UVP,NVP,OCP
Min.
Typ.
Max.
Unit
200
300
400
mS
75
150
300
uS
0.68
0.7
0.72
V
0.68
0.7
0.72
V
UVAC < VUVAC(DIS)
75
150
300
uS
UVAC > VUVAC(DIS)
15
25
35
mS
PG Output Rising Time
CL =100pF Pull 2.2K to
5V
1
3
uS
TF *2
PG Falling Time
CL =100pF Pull 2.2K to
5V
300
500
nS
VOL2
Power Good Output Saturation Level
IPG = 5mA
0.5
V
IIO2
Power Good Leakage Current
VPG = 5V
1
uA
TR
*2
Test Condition
UVAC to PG
Note *2: Not tested in production test;
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-7-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
Remote On/Off
Symbol
Parameter
VPSON
PSON Input Threshold Level
Test Condition
Min.
Typ.
Max.
Unit
1
1.4
2.0
V
IPSON
Remote Input Driving Current
TPSON(ON)
TPSON(OFF)
PSON to On/Off Time
On
Off
0.5
mA
25
8
45
16
65
24
mS
TPSOFF
PG Low to Power Off Time
1.5
2
6.3
mS
Min.
Typ.
Max.
Unit
2.45
2.5
2.55
V
0.1
uA
30
mV
Error Amplifier
Symbol
Parameter
V2.5
Reference Voltage
Test Condition
IIB*2
Input Bias Current
VDEV,T2.5 *2
Deviation of V2.5 Over Temperature
ICOSI
ICOMP Source Current
IN Short COMP
VCOMP=2.4V
0.4
mA
ICOSO
ICOMP Sink Current
IN Short COMP
VCOMP=2.6V
1.2
mA
AVOL * 2
Open-Loop Voltage Gain
50
60
BW * 2
Unity Gain Bandwidth
0.3
1
PSRR * 2
Power Supply Rejection Ratio
50
10
dB
MHz
dB
Oscillator Section
Symbol
Parameter
Min.
Typ.
Max.
Unit
FOSC
PWM Frequency
Test Condition
60
65
70
KHz
DCMAX
Max Duty Cycle
41
44.5
48
%
RI
RI Resistor Range
70
105
KΩ
VREFRI
RI Reference Voltage
0.98
1
1.02
V
TDEAD
PWM Dead Time
1.3
1.7
2.1
uS
Soft-Start Section
Symbol
Parameter
Min.
Typ.
Max.
Unit
ISS
Charge Current
Test Condition
6.7
8
9.3
uA
ISSINK
Sink Current
1
mA
PWM Output Section (OP1, OP2)
Symbol
Parameter
Test Condition
VOL
Output Voltage Low
Io = 20mA
VOH
Output Voltage High
VDD = 5V
RO
Output Impedance of VOH
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
Min.
Max.
Unit
1
V
2.6
kΩ
4
0.8
-8-
Typ.
V
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
TYPICAL CHARACTERISTICS
N egativ e V oltage P rotec tion: V oltage Lev el (V N V P ) v s
Total S upply C urrent (IC C 1 ) v s Tem perature
Tem perature
3.5
15
3.0
10
V N V P ( V)
IC C 1 (m A )
13
8
2.5
2.0
5
1.5
3
1.0
0
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
65
80
95
110
125
69
2.37
68
2.35
2.33
I NVP (uA )
(V)
50
v s Tem perature
(V O P P * 1 ) v s Tem perature
1
35
N egativ e V oltage P r otec tion: S ourc e C urrent ( IN V P )
O v er- P ow er P rotec tion ( W ith T O P P delay tim e)
V OPP *
20
Tem perature (℃)
Tem perature (℃ )
2.31
2.29
2.27
67
66
65
2.25
64
2.23
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
20
35
50
65
80
95
110
125
Tem perature (℃ )
T em per ature (℃ )
Timing for Over-Power-Protection ( T O P P ) vs T e mp e r a tu r e
O v er P ow er P rotec tion (W ithout delay tim e) (V O P P H )
8.0
v s Tem perature
3.4
7.5
7.0
TOP P ( m S)
V OPPH (V )
3.3
3.2
6.5
6.0
5.5
5.0
3.1
4.5
4.0
-40
3.0
-40
-25
-10
5
20
35
50
65
Tem perature (℃)
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
80
95
110
125
-25
-10
5
20
35
50
65
80
95
110
125
T e mp e r a tu r e ( ℃ )
-9-
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
Tim ing for O v er-C urrent P r otec tion (T O C P ) v s
VS1 2 L e a ka g e C u r r e n t ( I L K 1 2 A B _ VS1 2 ) v s
Tem per ature
T e mp e r a t u r e
25
20
IL K 1 2 A B _VS 1 2 ( u A)
T OCP (m S )
23
21
19
17
15
19
18
17
16
15
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
20
35
50
65
80
95
110
125
T e mp e r a t u r e ( ℃ )
T em perature (℃ )
O C P C om par ator Input O ffs et V oltage (V O F F S E T ) v s
V S 12B Leak age C urrent ( IL K 1 2 A B _ V S 12B ) v s
Tem perature
T em perature
5.0
20
I L K 1 2 A B _ V S 12B (uA )
V O F F S E T (m V )
3.0
1.0
-1.0
-3.0
19
18
17
16
15
-5.0
-40
-25
-10
5
20
35
50
T e mp e r a t u r e ( ℃ )
65
80
95
110
-40
125
-10
5
20
35
50
65
80
95
110
125
T em perature (℃ )
U VAC Vo lta g e Se n s e f o r PG ( V U V A C ) v s T e mp e r a t u r e
R atio of IS 12 to R I C urrent S etting ( IR E F ) v s
Tem perature
0.72
8.4
8.3
0.71
V UV AC (V)
8.2
IR E F
-25
8.1
8.0
7.9
0.70
0.69
7.8
7.7
-40
-25
-10
5
20
35
50
65
80
95
110
0.68
125
-40
Tem perature (℃ )
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-25
-10
5
20
35
50
65
80
95
110
125
T e mp e r a tu r e ( ℃ )
- 10 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
R eferenc e V oltage (V 2 . 5 ) v s T em per ature
R I R e fe r e n c e Vo lt a g e (V R E F R I ) vs T e mp e r a t u r e
2.55
1.02
2.53
1.01
V R E F R I (V)
V 2.5 (V )
2.51
2.49
1.00
0.99
2.47
2.45
0.98
-40
-25
-10
5
20
35
50
65
80
95
110
125
-40
-25
-10
5
Tem perature (℃ )
95
110
125
110
125
110
125
1.8
70
1.7
T D E A D (u S)
68
FOSC (K Hz )
80
PW M D e a d T ime ( T D E A D ) vs T e mp e r a tu r e
PW M F r e q u e n cy ( F O S C ) v s T e mp e r a tu r e
66
64
1.6
1.5
1.4
62
1.3
60
-40
-25
-10
5
20
35
50
65
80
95
110
-40
125
-25
-10
5
20
35
50
65
80
95
T e mp e r a tu r e ( ℃ )
T em p era t ure (℃ )
C harge C urrent (IS S ) v s Tem perature
M ax D uty C y c le (D C M A X ) v s T em perature
8.6
47
8.4
46
8.2
45
IS S (uA )
D C M A X (% )
20
35
50
65
T em perat ure (℃ )
44
43
8.0
7.8
7.6
42
-40
-25
-10
5
20
35
50
65
80
95
110
7.4
125
-40
T em perature (℃ )
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
-25
-10
5
20
35
50
65
80
95
Tem perature (℃ )
- 11 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
Operation description
Application Guides
Protection against over-voltage, short-circuit and fault
conditions is mandatory for PC power supplies. Many
commonly used protection circuits require large numbers
of discrete components and comparators which occupy
significant PCB space and add to assembly costs. This
single chip controller IC provides complete protection,
shunt regulation, and PWM control with comparatively
few components. The SG6108 is an ideal controller IC for
PC switching mode power supplies. The features and
benefits of this device are listed on the first page.
The application guide shows the key features of the
SG6108 and illustrates how to use it in an ATX switching
mode power supply (SMPS). The SG6108 is suitable for
half-bridge, push-pull topologies. The PWM section of
the SG6108 comprises a built-in 65kHz oscillator and
high immunity circuits, which protect the system from
noise interference and provide higher noise margins
against improper PCB layout. The SG6108 has OVP,
UVP, and OCP for the 3.3V and 5V signals, as wells as
both 12V signals. NVP is used for negative voltage
protection (–12V/–5V). UVAC (AC failure detection) is
used to measure the AC line voltage.
Feature Notes
„
„
„
„
„
„
Over voltage protection can be implemented without
any additional components. Over-voltage sense
levels are 3.3V/5V/12V or 4.1V/6.1V/14.05V.
The SG6108’s over current protection monitors the
3.3V, 5V, and the two 12V levels. The voltage
difference across the external current shunt is used to
provide accurate OCP.
Over current and/or short circuit protection can also
be implemented by using over-power protection. To
do this, the OPP pin must be connected to the current
transformer (driver transformer).
The power good signal is asserted to indicate that the
3.3V/5V/12V signals are above the under voltage
threshold level. The PG pin goes high when the
above condition is reached. A 2kΩ pull up resistor
may be optionally connected to the 5V lead.
VCC can be supplied from the 5V-standby.
Whenever the VCC voltage exceeds 7V the entire
SG6108 will be shutdown and reset (except for the
shunt regulator). No extra power supply is needed.
Complete PWM control circuitry includes an error
amplifier for push-pull or half-bridge operation.
Supervisory Circuit Operation
The PC generates the remote ON/OFF logic (PSON)
signal. When this is “Low” the power supply is “On”.
When it is “High”, the power supply is switched off. The
remote ON/OFF signal is supplied to the PSON input.
AC Failure Detection
UVAC is connected to the secondary power transformer
through a resistor divider. UVAC is used for detecting the
AC line voltage. Whenever the UVAC voltage drops
below 0.7V for a period of time such as 150usec, the PG
(power good) signal will be pulled low to indicate an AC
line power-down condition.
The voltage amplitude of the PWM switching signal in the
secondary power transformer is proportional to the AC
line voltage. The power-down warning threshold can be
controlled by adjusting the resistor-divider ratio. A small
VS
Vo
Vin
R1
+
R2
C1
UVAC
0.7V
capacitor must be connected between UVAC and ground
to filter the switching noise.
Over Power Protection (OPP)
OPP (over power protection) is used to detect over power
and short-circuit conditions. Whenever the VOPP voltage
(p.7, Note-1) exceeds 2.3V for longer than 6msec the
SG6108 will pull PG low and lock off the power outputs.
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
- 12 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
OP1
Vdd
OP2
R1
R2
OPP
C1
R3
Negative Voltage Protection
NVP provides UVP (under voltage protection) for
negative voltage outputs. An under-voltage condition
indicates an overload at a negative voltage output. For
example, the –12V output may drop to –10V during
overload situations. The resistance of a resistor connected
from NVP to the negative voltage output determines the
protection threshold voltage. NVP outputs a 64uA
constant current to the negative voltage output via this
resistor. Whenever the NVP voltage exceeds 2.1V for
longer than 7 msec the SG6108 will lock the power
outputs off.
Over Current Protection (OCP)
The SG6108 provides over current protection for the
3.3V, 5V and the two 12V rails. Whenever an OCP
condition occurs at any of the voltage rails, PG will be low
and PWM will be turned off. The internal OCP
VNVP = 64 uA × (R1 + R2) – V-12V
The power outputs will be locked off when VNVP ≥
2.1V.
64uA
comparators have a very small offset voltage (±5mV).
R1
+
The sink currents of IS33, IS5, and IS12 are 8 times the
current at the RI pin. The current at the RI pin is VRI/RI.
Here is an example demonstrating how to set the over
current protection threshold:
R2
-12V
2.1V
-5V
IRI = VRI/RI = 1.0V/75k = 13.3uA
If R1 = 1700Ω and R12 = 0.01Ω, then
OC P = 13.3uA x 8 x 1700 / 0.01 = 18 A
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
- 13 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
REFERENCE CIRCUIT
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
- 14 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
PACKAGE INFORMATION
20 PINS – DIP (D)
θ
D
11
20
E1
eB
E
10
1
A2
A
L
e
b1
A1
b
Dimensions
Symbol
A
A1
A2
b
b1
D
E
E1
e
L
eB
θ˚
Millimeters
Min.
Typ.
Max.
Inches
Min.
Typ.
5.334
0.381
3.175
24.892
6.223
2.921
8.509
0°
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
3.302
1.524
0.457
26.162
7.620
6.350
2.540
3.302
9.017
7°
3.429
0.015
0.125
26.924
0.980
6.477
0.245
3.810
9.525
15°
0.115
0.335
0°
- 15 -
Max.
0.210
0.130
0.060
0.018
1.030
0.300
0.250
0.100
0.130
0.355
7°
0.135
1.060
0.255
0.150
0.375
15°
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007
Product Specification
SG6108
Power Supply Supervisor + PWM
© System General Corp.
Version 1.0.1 (IAO33.0048.B0)
- 16 -
www.sg.com.tw • www.fairchildsemi.com
September 26, 2007