MIC68401 Datasheet, PDF (1/13 Pages) Micrel Semiconductor – 4A Sequencing LDO with Tracking and Ramp Control™

MIC68401
4A Sequencing LDO with Tracking and
Ramp Control™
General Description
The MIC68401 is a high peak current LDO regulator
designed specifically for powering applications such as
FPGA core voltages that require high startup current with
lower nominal operating current. Capable of sourcing 4A of
current for start-up, the MIC68401 provides high power
from a small QFN package. The MIC68401 can also
implement a variety of power-up and power-down
protocols such as sequencing, tracking, and ratiometric
tracking.
The MIC68401 operates from a wide input range of 1.65V
to 5.5V, which includes all of the main supply voltages
commonly available today. It is designed to drive digital
circuits requiring low voltage at high currents (i.e., PLDs,
DSPs, microcontrollers, etc.). The MIC68401 incorporates
a delay pin (DELAY) for control of power-on-reset (POR)
output at turn-on. In addition, there is a ramp control (RC)
for either tracking applications or output voltage slew rate
control at turn-on. These features are important in
applications where the load is highly capacitive and inrush
currents can cause supply voltages to fail and
microprocessors or other complex logic chips to hang up.
Multiple MIC68401s can be “daisy chained” in two modes.
In tracking mode the output voltage of the master drives
the RC pin of a slave so that the slave tracks the main
regulator during turn-on and turn-off. In sequencing mode
the POR of the master drives the enable (EN) of the slave
so that it turns on after the master. This behavior is critical
for power-up control in multi-output power supplies. The
MIC68401 is fully protected offering both thermal, current
limit protection, and reverse current protection.
The MIC68401 has an adjustable output voltage. The
junction temperature range of part is rated from –40°C to
+125°C. The MIC68401 is offered in the small 16-pin 4mm
× 4mm QFN package.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
• Stable with 10µF ceramic capacitor
• Input voltage range: 1.65V to 5.5V
• Low 0.5V reference voltage
• ±2.0% output tolerance over temperature
• 4A output current
• Timing-controlled sequencing on/off
• Programmable Ramp Control™ for inrush current
limiting and slew rate control of the output voltage during
turn-on
• Power-on-reset (POR) supervisor with programmable
delay time
• Single master can control multiple slave regulators with
tracking output voltages
• Small 4mm × 4mm QFN package
• Maximum dropout (V_IN – V_OUT) of 500mV over
temperature at 3A output current
• Fixed and adjustable output voltages
• Excellent line and load regulation specifications
• Logic-controlled shutdown
• Thermal shutdown and current-limit protection
Applications
• FPGA/PLD power supply
• Networking/telecom equipment
• Microprocessor core voltage
• High-efficiency linear post regulator
• Sequenced or tracked power supply
Ramp Control is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax + 1 [phone] • http://www.micrel.com
November 7, 2013
Revision 1.0