SC4431 Datasheet

SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Description
Features
The SC4431 is a four terminal device for regulating an
isolated power supply with output voltages down to 1.5V.
 Open Collector output drives Optoisolator with
It is intended to be used as a replacement for three
terminal shunt regulators such as SC431L where the
output voltage is too low for the device to function in
conjunction with an opto-isolator. SC4431 achieves this
by having seperate supply and output pins, allowing the
output to sink current at voltages as low as 0.1V, while
the supply pin still has sufficient voltage for the device to
function. In this way, allowing for a 1.4V drop through an
opto-isolator diode, regulation down to 1.5V out can be
achieved.

The SC4431 shunt regulator is available with three
initial reference voltage accuracies (0.5%, 1.0% and
2.0%) in the space saving 5-lead SOT-23 package. The
three voltage tolerances allow the designer the
opportunity to select the proper cost/tolerance for their
application.
 Telecom Power Supplies
 Opto driver for very low output voltage (1.5V)






as little as 1.5V input voltage
Trimmed bandgap design - initial accuracies
to + 0.5%
40mA drive capability
Regulates output as low as 50mV
Wide supply voltage range - 1.5V to 15V
Low supply current - typically 110μA
Full industrial temperature range
SOT-23-5 package
Applications
isolated power supplies
 Battery operated applications
 Point of use power supplies
Lead free, fully WEEE and ROHS compliant
Typical Application Circuit
2V Output Isolated Power Supply
2V OUT
T1
VIN
Primary Side
Controller
Secondary Side
Rectification
and Filtering
R1
R2
5.1k
U1
C1
C3
33nF
SC4431
5
1
VCC
OUT
4N25
R3
6.34k
4
REF
C2
22nF
3
NC
R4
10k
2 GND
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Absolute Maximum Rating
Parameter
Symbol
Maximum
Units
V CC
ICC
VOUT
VREF
IOUT
IREF
-0.5 to +16
8
-0.5 to VCC
-0.5 to +4
40
5
V
mA
V
V
mA
mA
Operating Ambient Temperature Range
Operating Junction Temperature Range
TA
TJ
-40 to +85
-40 to +150
°C
°C
Storage Temperature Range
Thermal Impedance Junction to Ambient
TSTG
θJ A
-65 to +150
256
°C
°C/W
Thermal Impedance Junction to Case
θJ C
81
°C/W
PD
TLEAD
ESD
475
300
2
mW
°C
kV
Input Supply Voltage
Vcc pin current
Output Voltage
Reference Voltage (1)
Continuous Output Current
Reference Input Current
Power Dissipation at TA = 25°C
Lead Temperature (Soldering) 10 seconds
ESD Rating (Human Body Model)
(1) If Vref will be forced above 1.224V, a resistor must be placed in series with the Vcc to limit the Icc current
below 5mA.
Electrical Characteristics
Unless specified, TA = 25° C, VCC = 2V, IOUT = 2mA. Values in bold apply over full operating temperature range.
Parameter
VCC
Input Supply Voltage
Input Supply Current
Off State Input Supply Current
REF
Reference Voltage
Symbol
Test Conditions
VCC
ICC
ICC(OFF)
VREF
MIN
T YP
MAX
Units
110
65
15
200
100
150
V
μA
μA
1.231
1.243
1.236
1.250
1.250
1.261
15
20
28
36
V
1.5
VREF
VREF = VOUT
= 1.187V, VOUT = 2V
SC4431-.5, VREF = VOUT
SC4431-1, VREF = VOUT
SC4431-2, VREF = VOUT
1.219
1.207
1.212
1.200
1.200
1.187
1.224
1.224
1.224
V
V
Change in VREF due to change in
Vcc
dVREF/dVCC
VCC = 1.5V to 15V
8
Change in VREF due to change in
IOUT
dVREF/dIOUT
IOUT = 0.1mA to 40mA
8
IREF
0.1mA ≤ IOUT ≤ 10mA
0.3
0.5
1.0
μA
VOUT(SAT)
IOUT = 5mA, ICC = 500μA
50
mV
VREF = 1.261V, IOUT = 32mA
275
VREF = 1.187V, VOUT = 2V
0.50
75
100
300
400
1
10
Reference Input Current
OUT
Saturation Voltage
Off State Output Current
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IOUT(OFF)
2
mV
mV
mV
μA
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Pin Configurations
Ordering Information
(TOP VIEW)
Part Number(1)(2)
P ackag e
SC4431CSK-X
SOT-23-5
Notes: (1) Only available in tape and reel packaging.
(Suffix ‘.TRT’ e.g. SC4431CSK-X.TRT).
(2) Where “-X” denotes initial reference voltage tolerance. Available options are ±0.5% (-.5), ±1% (-1) and
±2% (-2).
(SO
T-23-5)
(SOT
Pin Descriptions
Pin#
Pin Name
Pin Function
1
VC C
This is the input supply pin for the SC4431. A low ESR capacitor should be used to bypass this
pin to GND right at the IC.
2
GND
Logic and power ground.
3
NC
No connection.
4
REF
This is connected to the non-inverting input of the error amplifier.
5
OUT
This is the output pin of the device, essentially an open collector.
Note: A 22nF low ESR (ceramic) capacitor is required from
this pin to GND for stable operation.
Marking Information
Block Diagram
Top Mark
4431
Bottom Mark
yyww
yyww = Datecode (Example: 9908)
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Typical Characteristics
Vref vs Ta Vcc = 2V
Vref vs Ta Iout = 2mA
1.228
1.236
Vcc=1.5V
Vcc=2V
Vcc=5V
Vcc=15V
1.227
1.226
Iout=2mA
1.234
Iout=100uA
1.232
1.225
1.224
Vref(V)
Vref(V)
Iout=40ma
1.223
1.222
1.221
1.230
1.228
1.226
1.220
1.224
1.219
1.218
-40 -30 -20 -10
0
10
20 30
40
50
60
70
1.222
80
-40 -30 -20 -10
0
10
Ta(Deg.C.)
20
30
40
50
60
70
80
Ta(Deg.C.)
Typical Vref vs Ta Vcc = 2V
Typical Vref vs Ta Io = 2mA
Icc Off vs Ta Vout = 2V
Iref vs Ta Vout = 2V
70E-6
13E-9
Icc_Off
Iref
12E-9
11E-9
65E-6
Iref (A)
Icc Off(A)
10E-9
60E-6
9E-9
8E-9
7E-9
55E-6
6E-9
5E-9
50E-6
4E-9
-40 -30 -20 -10
0
10
20
30 40 50
60
70 80
-40 -30 -20 -10
0
10
Ta(Deg.C.)
20
30 40 50
60
70 80
Ta(Deg.C.)
Typical Iout vs Ta Vo = 2V
Typical Icc Off vs Ta Vo = 2V
Iref vs Ta Vcc = 2V
Vsat vs Ta Vcc = 2V
45E-9
Iout=100uA
350
Iout=1mA
Iout=2mA
40E-9
300
Iout=40ma
Iout=5mA
Iout=5mA
Iout=10mA
250
Iout=15mA
Iref(A)
Vsat(mV)
35E-9
30E-9
200
150
100
25E-9
50
0
20E-9
-40 -30 -20 -10
0
10
20
30
40
50
60
70
-40 -30 -20 -10
80
10
20
30
40
50
60
70
80
Ta(Deg.C.)
Ta(Deg.C.)
Typical Vsat vs Ta Vcc = 2V
Typical Iref vs Ta Vcc = 2V
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
3.5000
3.5000
3.0000
3.0000
2.5000
2.5000
2.0000
2.0000
Icc(mA)
Icc(mA)
Typical Characteristics
1.5000
1.5000
1.0000
1.0000
0.5000
0.5000
0.0000
0.0000
-0.5000
-0.5000
1.2248
1.2703
1.3048
1.7030
1.2243
3.0182
1.2700
Vcc=2V,Io=1.3mA
1.3009
1.7073
3.0073
Vref(v)
Vref(v)
Vcc=5V,Io=1.3mA
Vcc=15V,Io=1.3mA
Vcc=2V,Io=2mA
Typical Icc vs Vref, Io = 1.3mA, Ta = 25 Deg.C.
Vcc=5V,Io=2mA
Vcc=15V,Io=2mA
Typical Icc vs Vref, Io = 2mA, Ta = 25 Deg.C.
+VCC
J1
+V adj
C1
10uF
1
2
+Vref_Adjust
R1
4k
Io
C3
1k
J3
1
2
C4
10uF
1
Vref
J2
3.9k
U1
R4
R2
5
4
Vo
C2
10uF
1
2
C5
22nF
R5
1k
Vref
SC4431
2
Icc vs Vref Test Circuit
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Typical Gain Phase
SC4431 Gain / Phase Vin = 2V, Iout = 2mA, Vout = 1.6V
200
70
60
150
Gain
50
Phase
100
50
30
20
0
Phase (deg)
Gain (dB)
40
10
-50
0
-100
-10
-20
10
100
1000
10000
100000
-150
1000000
Freq (Hz)
SC4431 Gain / Phase Vin = 4V, Iout = 2mA, Vout = 2V
80
200
70
Gain
150
60
50
100
Gain (dB)
30
50
Phase (deg)
Phase
40
20
0
10
0
-50
-10
-20
10
100
1000
10000
100000
-100
1000000
Freq (Hz)
R1
J1
A
J2
R
1 2 3 4 5
1k for 2mA
1 2 3 4 5
U1
J3
1
1
2
4V IN
3
VCC
OUT
5
2V OUT
GND
NC
REF
4
R2
3.16k
SC4431
C1
10u
R3
C3
C2
0.1u
C4
22u
C5
22u
C7
22n
C6
22u
5.1k
R4
4.99k
33n
J4
1
GND
J5
1
2
3
4
5
Signal In
Gain Phase Test Circuit
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Typical Applications
+V Monitor
+Vcc
C1
Power Good
R2
R1
R4
R3
U1
1
5
Q1
4
C2
C4
C3
22nF
R5
Vref
SC4431
2
Power good Circuit
+Vcc
+Vout Secondary
C1
R1
R2
+Vprimary
1
R3
R4
5
U2
C3
4
C2
22n
U1
SC4431
PWM disable
R5
C4
Vref
2
Isolated OVP Circuit
+Vin
+Vout
Q1
C1
R1
1
R2
U1
R3
5
4
C2
R4
22nF
C3
Vref
2
SC4431
Linear Regulator Circuit
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SC4431
Shunt Regulator With
Open Collector Output
POWER MANAGEMENT
Outline Drawing
SO
T-23- 5L
SOT
ECN00 - 88
1
881
Land Pattern
SO
T- 23- 5L
SOT
ECN00 - 88
1
881
Contact Information
Semtech Corporation
Power Management Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805)498-2111 FAX (805)498-3804
© 2003 Semtech Corp.
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