Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - LDO voltage regulator Positive, fixed or adjustable TO 263 5

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SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

D Fast Transient Response

D 10-mA to 5-A Load Current

D Short Circuit Protection

D Maximum Dropout of 500-mV at 5-A Load

Current

D Separate Bias (VB) and VIN Pins

D Available in Adjustable or Fixed Output

Voltages

D 5-Pin Package Allows Kelvin Sensing of

Load Voltage

D Reverse Current Protection

description

The UC385 is a low dropout linear regulator providing a quick response to fast load changes. Combined with

its precision onboard reference, the UC385 excels at driving GTL and BTL buses. Due to its fast response to

load transients, the total capacitance required to decouple the regulator’s output can be significantly decreased

when compared to standard LDO linear regulators.

Dropout voltage (VIN to VOUT) is only 490 mV maximum and 350 mV typical at 5-A load (0°C to 100°C).

The onboard bandgap reference is stable with temperature and scaled for a 1.2 V input to the internal power

amplifier. The UC385 is available in fixed output voltages of 1.5 V, 2.1 V, or 2.5 V. The output voltage of the

adjustable version can be set with two external resistors. If the external resistors are omitted, the output voltage

defaults to 1.2 V.

block diagram

THERMAL

SHUTDOWN

1.2 V

BANDGAP

REFERENCE

3 5

SHORT

CIRCUIT

SENSE

UC382−ADJ

UC382−1 (1.5 V)

UC382−2 (2.1 V)

UC382−3 (2.5 V)

OPEN 0

2 k 500

Ω

2 k 1.5 k

Ω

2 k 2.16 k

Ω

R1 R2

ADJGND VOUT

VIN

UDG-00084

Ω

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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.

5-PIN TO-263

TD PACKAGE

(TOP VIEW)

5-PIN TO-220

T PACKAGE (TOP VIEW)

Note: Tab = Ground

All trademarks are the property of their respective owners.

Summary of content (12 pages)

PAGE 1
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 D D D D D D D D Fast Transient Response 10-mA to 5-A Load Current Short Circuit Protection Maximum Dropout of 500-mV at 5-A Load Current Separate Bias (VB) and VIN Pins Available in Adjustable or Fixed Output Voltages 5-Pin Package Allows Kelvin Sensing of Load Voltage Reverse Current Protection 5-PIN TO-220 T PACKAGE (TOP VIEW) 5-PIN T
PAGE 2
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 absolute maximum ratings over operating free-air temperature (unless otherwise noted)† VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 V Output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PAGE 3
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 electrical characteristics unless otherwise stated, these parameters apply for TA = −40°C to 100°C for the UC285-x series and 0°C to 100°C for the UC385-x, VB = 5 V; VIN = 3.3 V, VOUT = 2.5 V, TA = TJ. PARAMETER TEST CONDITION MIN TYP MAX UNIT 350 425 mV 350 490 mV 350 500 mV UC385-2 IVOUT = 5 A IVOUT = 5 A 1.8 2.
PAGE 4
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 pin descriptions ADJ: In the adjustable version, the user programs the output voltage with two external resistors. The resistors should be 0.1% for high accuracy. The output amplifier is configured as a noninverting operational amplifier. The resistors should meet the criteria of R3 || R4 < 100 Ω.
PAGE 5
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 APPLICATION INFORMATION The UC385 is easy to use. The adjustable version requires two resistors to set the output voltage. The fixed versions of the UC385 require no external resistors. All versions of the UC385 require decoupling capacitors on the input and output.
PAGE 6
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 APPLICATION INFORMATION PSSR - Power Supply Rejection Ratio (VB Input) − dB POWER SUPPLY REJECTION RATIO (VB INPUT) vs. FREQUENCY 60 50 40 30 20 10 0 100 1k 10 k 100 k 1M 10 M f − Frequency − Hz Figure 5 1µ F Ceramic + _ 5V 1 2 + + _ 3.3 V 4.7µ F Tantalum VIN VB VOUT 4 + UC385−ADJ GND ADJ IRF 520 VO = 1.
PAGE 7
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 APPLICATION INFORMATION 10 mA to 3 A/µs Load Transient Response 20 10 0 −10 3 −20 2 1 0 I O − Load Current − A ∆ VO − Change in Output Voltage − mV 2 µs/DIV Figure 7 +5 V + 4.7µ F Kelvin Sense Point 1 +3.3 V 2 + 4.7 µ F VIN VB VOUT 4 R3 60 Ω UC385−ADJ GND ADJ 3 + 330 µ F OSCON +1.8 V Output F 2.
PAGE 8
SLUS212E − NOVEMBER 1999 − REVISED FEBRUARY 2004 APPLICATION INFORMATION +5 V + 4.7 µ F Kelvin Sense Point 1 2 VIN VB VOUT + UC385−1 GND +1.5 V Output 4 ADJ 330 µ F OSCON 2.2 µF Ceramic 5 3 UDG-00087 Figure 9.
PAGE 9
PACKAGE OPTION ADDENDUM www.ti.
PAGE 10
PAGE 11
MECHANICAL DATA MSOT008B – JANUARY 1995 – REVISED SEPTEMBER 2000 KC (R-PSFM-T5) PLASTIC FLANGE-MOUNT 0.113 (2,87) 0.103 (2,62) 0.420 (10,67) 0.380 (9,65) 0.156 (3,96) DIA 0.146 (3,71) 0.185 (4,70) 0.175 (4,46) 0.055 (1,40) 0.045 (1,14) 0.147 (3,73) 0.137 (3,48) 0.340 (8,64) 0.330 (8,38) 1.037 (26,34) 0.997 (25,32) 0.125 (3,18) (see Note C) 1 0.040 (1,02) 0.030 (0,76) 0.010 (0,25) M 5 0.067 (1,70) 0.268 (6,81) 0.122 (3,10) 0.102 (2,59) 0.025 (0,64) 0.012 (0,30) 4040208/E 09/00 NOTES: A. B. C.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.