
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
V
IN
V
OUT
Fixed Regulator Configuration
MIC29312
OUT
ADJ
R1*
V
OUT
* For best performance, total series resistance
(R1 + R2) should be small enough to pass
the minimum regulator load current of 10mA.
R2*
EN
GND
V
IN
IN
On
Off
V
OUT
= 1.240
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