®
SPX2945
400mA Low Dropout Voltage Regulator with Shutdown
FEATURES
1.2V to 20V
1
7
8
+VIN
+VIN
VOUT
+
■ Output 3.3V, 5.0V at 400mA Output
■ Very Low Quiescent Current, 100µA
■ Low Dropout Voltage, 420mV at 400mA
■ Extremely Tight Load and Line Regulation
■ Very Low Temperature Coefficient
■ Current & Thermal Limiting
100K
OFF
0.01µF
10µF
R1
FB
SPX2945
______
ERROR
SHUTDOWN
INPUT
ERROR
SD
3
5
OUTPUT
GND
4
VREF
R2
ON
Adjustable Regulator
■ Error Flag Warns Of Output Dropout
■ Logic-Controlled Electronic Shutdown
5V
VIN
IN
OUT
■ Output Programmable From 1.24V to 20V
(for SO-8)
SPX2945
+
+
2.2 µF
GND
0.1 µF
5V Regulator Circuit
DESCRIPTION
TheSPX2945isalowpowervoltageregulator.Thisdeviceisanexcellentchoiceforuseinbattery-powered
applications such as cordless telephones, radio control systems, and portable computers. The SPX2945
features very low quiescent current (100µA Typ.) and very low dropout voltage. This includes a tight initial
tolerance of 1% max and very low output temperature coefficient, making the SPX2945 useful as a low-
power voltage reference.
The error flag output feature is used as power-on reset for warning of a low output voltage, due to a falling
voltage input of batteries. Another feature is the logic-compatible shutdown input which enables the
regulator to be switched on and off. The SPX2945 is offered in 3-pin TO-220 package, SO-8 (same pin
out as SPX2951), SOT-223, surface mount 3-Pin TO-252, 3-Pin TO-263 packages and 5-Pin TO-263.
The regulator output voltage (of the 8-pin SO-8) may be pin-strapped for a 3.3V and 5.0V or programmed
from1.24Vto20Vwithanexternalpairofresistors. LookforSPX2951for150mAandSPX2954for250mA
applications.
TO-252 (R)
TO-263-5 (T5)
8-Pin Surface Mount
SOT-223 (M3)
(S)
TO-220-3 (U)
TO-263-3 (T)
VOU
1
8
7
VIN
SPX2945
SPX2945
SPX2945
2
SPX2945
5 Pin TO-263
SPX2945
SENS
SHUTDOWN
GN
FEEDBACK
5V/ 3.3V TAP
ERRO
SPX2945
1
2
3
1
2
3
1
3
2
3
4
6
5
1
2
3
1
2 3 4 5
VIN
VOU
GN
VIN GN VOU
VIN GN
VOU
VIN GN VOU
Rev. B Date:01/20/04
SPX2945 400mA Low Dropout Voltage Regulator with Shutdown
©Copyright 2004 Sipex Corporation
1