July 1999

1

MIC29310/29312

MIC29310/29312

Micrel

General Description

The MIC29310 and MIC29312 are low cost versions of

MIC29300 family low-dropout (LDO) regulators. Manufac-

tured on Micrel’s proprietary Super beta PNP™ process, the

MIC29310/2 is a 3A LDO regulator with very low-dropout

voltage (600mV over the full load) and low ground current.

Along with a total accuracy of

±2% (over temperature, line

and load regulation) these regulators feature very fast tran-

sient recovery from input voltage surges and output load

current changes.

The MIC29310 is available in fixed 3.3V and 5V outputs

voltages; the MIC29312 has an adjustable output which can

be set by two external resistors to a voltage between 1.24V

to 15V. In addition, all versions are fully protected against

overcurrent faults, reversed input polarity, reversed lead

insertion, and overtemperature operation.

A TTL logic enable (EN) pin is available in the MIC29312 to

shutdown the regulator. When not used, the device can be

set to continuous operation by connecting EN to the input

(IN).

The MIC29310/2 is available in the standard 3- and 5-pin

TO-220 and TO-263 packages with an operating junction

temperature range of 0

°C to +125°C.

Features

• Low cost versions of MIC29300 family

• Fast transient response

• 3A current over full temperature range

• 600mV dropout voltage at full load

• Low ground current

• Accurate 1% guaranteed tolerance

• “Zero” current shutdown mode (MIC29312)

• Fixed voltage and adjustable versions

Applications

• Processor peripheral and I/O supplies

• PC add-in cards

• High-efficiency “green” computer systems

• High-efficiency linear power supplies

• High-efficiency switching supply post regulator

• Battery-powered equipment

MIC29310/29312

3A Fast-Response LDO Regulator

Typical Application

IN

OUT

GND

Fixed Regulator Configuration

MIC29312

OUT

ADJ

R1*

* For best performance, total series resistance

(R1 + R2) should be small enough to pass

the minimum regulator load current of 10mA.

R2*

EN

GND

IN

On

Off

R1

R2

+ 1

Adjustable Regulator Configuration

Ordering Information

Part Number

Voltage

Junction Temp. Range

Package

MIC29310-3.3BT

3.3V

0

°C to +125°C

TO-220-3

MIC29310-3.3BU

3.3V

0

°C to +125°C

TO-263-3

MIC29310-5.0BT

5.0V

0

°C to +125°C

TO-220-3

MIC29310-5.0BU

5.0V

0

°C to +125°C

TO-263-3

MIC29312BT

Adj.

0

°C to +125°C

TO-220-5

MIC29312BU

Adj.

0

°C to +125°C

TO-263-5

For applications requiring even lower dropout

voltage, input voltage greater than 16V, or an

error flag, see the MIC29300/29301/29302/

29303.

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com