ST TS4431 User Manual

TS4431

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: 250 A

■Industrial temperature range: -40 to +85°C

■100ppm/°C temperature coefficient

Description

The TS4431 is a four-terminal device dedicated to low voltage Switch Mode Power Supplies (SMPS).

It integrates a 1.224V voltage reference, an amplifier, and an open collector output transistor in a single package. The TS4431’s operating mode is similar to the well-known standard 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.

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.

SOT23-5L

(Plastic Micropackage)

Pin connections (top view)

	1	Vcc		Sink	5
		Gnd
	2
		Nc		Ref
	3				4

Applications

■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	L288
	TS4431ILT	1%				L275

	Rev 2
November 2005	1/8
	www.st.com

Absolute Maximum Ratings

TS4431

1 Absolute Maximum Ratings

Table 1.	Key parameters and their absolute maximum ratings
Symbol	Parameter		Value	Unit
ISINK	Output sink current		30	mA
VCC	Supply voltage		12	V
VSINK	Output voltage		12	V
PD	Power Dissipation (1)SOT23-5		500	mW
TSTD	Storage Temperature		-65 to +150	°C
ESD	Human Body Model (HBM)		2	kV
	Machine Model (MM)		200	V
TLEAD	Lead Temperature (soldering, 10 seconds)		250	°C

1.PD has been calculated with TAMB = 25°C, TJunction=150°C and RthJA = 250°C/W for the SOT23-5 package

RthJC = 81°C/W for the SOT23-5 package

Table 2.	Operating conditions
Symbol	Parameter	Value	Unit
TOPER	Operating temperature range	-40 to +85	°C
VCC	Supply voltage	1.5 to 10	V
ISINK	Output sink current	20	mA

2/8

Typical Application Schematic

TS4431

2 Typical Application Schematic

Figure 1. SMPS power supply: secondary side

D1		L1			Vout
		D2	C1
R1
1	Vcc	U1	Sink	5	R2
		TS4431
Cd1
100nF
2	Gnd	Vref
					R3
3 Nc			Ref	4

3/8