Micrel MIC24055 Manual

General Description

The MIC24055 DC/DC synchronous buck regulator operates
over an input supply range of 4.5V to 19V and provides a
regulated output at up to 12A of load current. The output
voltage is adjustable down to 0.8V with a typical accuracy of
±1%. The device operates at a switching frequency of
600kHz, which remains relatively constant with changes in
input voltage and output load.
Micrel's Hyper Speed Control architecture allows for ultra-
fast transient response
capacitance. It also makes (High V
possible. The 19V operating rating of the device provides
ample design safety margin for 12V input applications.
The MIC24055 utilizes an adaptive T
architecture. An undervoltage lockout feature is provided to
ensure proper operation under power-sag conditions. An
internal soft-start feature is provided to reduce the inrush
current. Foldback current limit and "hiccup" mode short-circuit
protection and thermal shutdown ensures protection of the IC
during fault conditions.
The basic parameters of the MIC24055 evaluation board are
a VIN supply of 5V to 19V, output voltage of 0.8V to 5V at
(1)
12A , and 600kHz switching frequency.
Note:
1. Refer to the temperature curves presented in the
Performance section. Also, note that the typical minimum input
voltage to maximum output voltage conversion is limited by the
maximum duty cycle.
Datasheets and support documentation are available on
Micrel's web site at: www.micrel.com.
Requirements
The MIC24055 evaluation board requires only a single
power supply with at least 10A current capability. The
MIC24055 has internal VDD LDO so no external linear
regulator is required to power the internal biasing of the IC.
When VIN < 5.5V, VDD should be tied to PVIN pins to
bypass the internal linear regulator by a jumper. The
output load can either be an active or passive load.
Hyper Speed Control, SuperSwitcher II, and Any Capacitor are trademarks of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
February 11, 2013
while reducing the
)/Low V ) operation
IN OUT
ripple control
ON
Evaluation Board
MIC24055 Evaluation Board
12A, High-Efficiency, Synchronous DC/DC
Buck Regulator with Hyper Speed Control™
Power-Up Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the VIN terminal
may damage the device. The maximum VIN operating
voltage of the MIC24055 evaluation board is 19V. It has
two different layout designs, one
evaluation and a second
footprint. The evaluation board is only populated with
components shown in

Getting Started

output
1. VIN Supply.
Connect a supply to the VIN and GND terminals,
paying careful attention to the polarity and the supply
range (5V < VIN < 19V). An ammeter may be placed
between the input supply and the VIN terminal to the
evaluation board. Ensure that the supply voltage is
monitored at the VIN terminal. The ammeter and/or
power lead resistance can reduce the voltage supplied
to the input. Do not apply power until Step 4.
2. Connect the load to the VOUT and ground
terminals.
The load can be either passive (resistive) or active (as
in an electronic load). An ammeter can be placed
between the load and the VOUT terminal. Ensure that
the output voltage is monitored at the VOUT terminal.
3. Enable Input.
An EN connector is provided on the evaluation board
for users to easily access the enable feature. The
output of the MIC24055 turns on when VDD exceeds
the UVLO threshold. The output of the MIC24055 may
be turned off by shorting the EN pin to ground.
4. Turn on the power.
Turn on VIN power supply and verify that the output
voltage is regulated to 1.8V.

Ordering Information

Part Number
MIC24055YJL EV
SuperSwitcher II™
(Figure
(Figure 2) optimized for a smaller
Figure 1.
Description
12A HSC DC/DC Buck Regulator
Evaluation Board
http://www.micrel.com
1) optimized for
Revision 1.0