ST TS4431 User Manual
1.224V Open Collector Shunt Voltage Reference
■ Internal 1.224V ±0.5% precision
■ Low output saturation voltage
75 mV max between SINK and GND
■ Low current consumption: 250µA
■ Industrial temperature range: -40 to +85°C
■ 100ppm/°C temperature coefficient
TS4431
SOT23-5L
(Plastic Micropackage)
Description
Pin connections (top view)
The TS4431 is a four-terminal device dedicated to
low voltage Switch Mode Power Supplies (SMPS).
Vc c
Sink
5
1
It integrates a 1.224V voltage reference, an
2
amplifier, and an open collector output transistor
Gnd
in a single package. The TS4431’s operating
mode is similar to the well-known standard
34
Nc Ref
voltage reference, the TL431. It maintains the
desired feedback voltage at the REF pin in a
closed loop configuration by sinking a current
proportional to the error voltage at the REF pin.
Applications
TS4431 features an open collector transistor with
an ultra-low saturation voltage, allowing it to be
used in series with the optocoupler in an SMPS
architecture to regulate low voltage SMPS.
■ Low voltage switch mode power supplies
■ Isolated DC/DC converter
■ Computers
■ Low voltage discrete regulator
Order Codes
Part Number Accuracy Temperature Range Package Packing Marking
TS4431AILT 0.5%
-40, +85°C SOT23-5 Tape & Reel
TS4431ILT 1% L275
November 2005 1/8
L288
Rev 2
www.st.com
8
Absolute Maximum Ratings TS4431
1 Absolute Maximum Ratings
Table 1. Key parameters and their absolute maximum ratings
Symbol Parameter Value Unit
I
SINK
V
V
T
SINK
P
STD
Output sink current 30 mA
Supply voltage 12 V
CC
Output voltage 12 V
Power Dissipation
D
(1)
SOT23-5
500 mW
Storage Temperature -65 to +150 °C
Human Body Model (HBM) 2 kV
ESD
Machine Model (MM) 200 V
T
LEAD
1. PD has been calculated with T
Rth
Rth
Lead Temperature (soldering, 10 seconds) 250 °C
= 25°C, T
= 250°C/W for the SOT23-5 package
JA
= 81°C/W for the SOT23-5 package
JC
AMB
Junction
=150°C and
Table 2. Operating conditions
Symbol Parameter Value Unit
T
OPER
V
I
SINK
Operating temperature range -40 to +85 °C
Supply voltage 1.5 to 10 V
CC
Output sink current 20 mA
2/8
Typical Application Schematic TS4431
2 Typical Application Schematic
Figure 1. SMPS power supply: secondary side
R1
Cd1
100nF
Vout
R2
R3
Vre f
D2
L1
U1
TS4431
C1
Si nk
5
Ref
D1
Vcc
1
Gn d
2
34
Nc
3/8
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