UCC284-EP
www.ti.com ....................................................................................................................................... SLVS862A–NOVEMBER 2008–REVISED NOVEMBER 2008
LOW-DROPOUT 0.5-A NEGATIVE LINEAR REGULATOR
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FEATURES
SUPPORTS DEFENSE, AEROSPACE AND
MEDICAL APPLICATIONS
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Precision Negative Series Pass Voltage
Regulation
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Controlled Baseline
One Assembly/Test Site
One Fabrication Site
Available in S-Temp (–55°C/100°C)
Temperature Range(1)
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0.2-V Dropout at 0.5 A
Wide Input Voltage Range –3.2 V to –15 V
Low Quiescent Current Irrespective of Load D
Simple Logic Shutdown Interfacing
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Extended Product Life Cycle
Extended Product-Change Notification
Product Traceability
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–5 V, –12 V, and Adjustable Output
2.5% Duty Cycle Short Circuit Protection
(1) Additional temperature ranges are available – contact factory.
D PACKAGE
(FRONT VIEW)
VOUTS
VIN
1
2
3
4
8
7
6
5
SD/CT
VIN
VIN
VIN
VOUT
GND
DESCRIPTION
The UCC284-x family of negative linear-series pass regulators is tailored for low-dropout applications where
low-quiescent power is important. Fabricated with a BCDMOS technology ideally suited for low input-to-output
differential applications, the UCC284-x passes 0.5 A while requiring only 0.2 V of input-voltage headroom.
Dropout voltage decreases linearly with output current, so that dropout at 50 mA is less than 20 mV.
Quiescent current consumption for the device under normal (non-dropout) conditions is typically 200 µA. An
integrated charge pump is internally enabled only when the device is operating near dropout with low VIN. This
ensured that the device meets the dropout specifications even for maximum load current and a VIN of –3.2 V
with only a modest increase in quiescent current. Quiescent current is always less than 360 µA, with the charge
pump enabled. The quiescent current of the UCC284 does not increase with load current.
Short-circuit current is internally limited. The device responds to a sustained overcurrent condition by turning off
after a tON delay. The device then stays off for a period, tOFF, that is 40 times the tON delay. The device then
begins pulsing on and off at the tON/tOFF duty cycle of 2.5%. This drastically reduces the power dissipation during
short circuit such that heat sinking, if at all required, must only accommodate normal operation. An external
capacitor sets the on time. The off time is always 40 times tON
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The UCC284-x can be shutdown to 45 µA (maximum) by pulling the SD/CT pin more positive than –0.7 V. To
allow for simpler interfacing, the SD/CT pin may be pulled up to 6 V above the ground pin without turning on
clamping diodes.
Internal power dissipation is further controlled with thermal-overload protection circuitry. Thermal shutdown
occurs if the junction temperature exceeds 140°C. The chip remains off until the temperature has dropped 20°C
(TJ = 120°C).
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2008, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.