AS2955/56/57
350mA Low Drop Out Voltage Regulator
with Shutdown
(PRELIMINARY INFORMATION)
FEATURES
APPLICATIONS
• Output Accuracy 5V, 3.3V@ 350mA Output
• Very Low Quiescent Current
• Battery Powered Systems
• Cordless Telephones
• Low Dropout Voltage
• Radio Control Systems
• Portable/Palm Top/Notebook Computers
• Portable Consumer Equipment
• Portable Instrumentation
• Automotive Electronics
• SMPS Post-Regulator
• Extremely Tight Load And Line Regulation
• Very Low Temperature Coefficient
• Current & Thermal Limiting
• Error Flag Warns Of Output Dropout
• Logic-Controlled Electronic Shutdown
• Output Programmable From 1.24V to 29V
• Voltage Reference
PRODUCT DESCRIPTION
The AS2955/56/57 is a low power voltage regulator. This device is an excellent choice for use in battery-powered applications such as
cordless telephones, radio control systems, and portable computers. The AS2955/56/57 features very low quiescent current (100µA
Typ.) and very low dropout voltage. This includes a tight initial tolerance of 1% max and 2% max., and very low output temperature
coefficient, making the AS2955/56/57 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 AS2955/56/57 is
offered in 3-pin and 5-pin TO-220 package compatible with other 5 volt and adjustable regulators, in 8-Pin Plastic Dip SO-8 (same pin
out as AS2951) and surface mount TO-263 packages.
The regulator output voltage (of the 8-pin package and 5-pin TO-220 & TO-263) may be pin-strapped for a 5V and 3.3V or
programmed from 1.24V to 29V with an external pair of resistors. Look for AS2951 for 150mA and AS2954 for 250mA applications.
ORDERING INFORMATION
TO-263-3 Package
AS2955
TO-220
TO-263
PLASTIC
SOIC
OPER.
TEMP.
RANGE
3 / 5- PIN
3 / 5-PIN
3
2
1
VOUT
GND
8-PIN
AS2955/56/57YU-X
AS2955/56/57YT-X
AS2955YS-X
-40 C to +125 C
°
°
Y= Output Tolerance(A = 1%; Blank for 2%)
Consult factory for other fixed voltages.
X= Output Voltage(3.3V, 5.0V or Blank for Adj)
V IN
TO-220-5 Package
Front View
TO-263-5 Package
8-Pin Surface Mount
1
2
8
7
OUTPUT
SENSE
INPUT
TO-220-3 Package
AS2956/57
AS2956/57
Five Lead Package Pin Functions:
FEEDBACK
ALPHA
AS2955
AS2956
ERROR
INPUT
AS2957
ADJUST
SHUTDOWN
GND
3
2
1
VOUT
GND
VIN
AS2930
3
4
SHUTDOWN
6
5
1)
2)
3)
4)
5)
5V/ 3.3V TAP
ERROR
AS2955
GROUND
GND
OUTPUT
INPUT
Front View
Top View
1
2 3 4
5
SHUTDOWN OUTPUT
1 2 3 4 5
Top View
Top View
Rev. 10/6/00