MIC28304 Evaluation Board
70V 3A Power Module
Hyper Speed Control Family
General Description Getting Started
The Micrel MIC28304 is synchronous step-down regulator
1. VIN Supply
module, featuring a unique adaptive ON-time control
Connect a supply to the VIN and GND terminals,
architecture. The module incorporates a DC-to-DC
paying careful attention to the polarity and the supply
controller, power MOSFETs, bootstrap diode, bootstrap
range (7V < VIN < 70V). Monitor IIN with a current
capacitor, and an inductor in a single package. The
meter and monitor input voltage at VIN and GND
MIC28304 operates over an input supply range of 4.5V to
terminals with a voltmeter. Do not apply power until
70V and can be used to supply up to 3A of output current.
step 4.
The output voltage is adjustable down to 0.8V with a
2. Connect Load and Monitor Output
guaranteed accuracy of 1%. The device operates with a
programmable switching frequency from 200kHz to
Connect a load to the VOUT and GND terminals. The
600kHz.
load can be either a passive (resistive) or an active (as
in an electronic load) type. A current meter may be
The MIC28304-1 has the HyperLight Load architecture,
placed between the VOUT terminal and load to
so it can operate in pulse skipping mode at light load.
monitor the output current. Ensure the output voltage
However, it operates in fixed frequency CCM mode from
is monitored at the VOUT terminal.
medium load to heavy load. The MIC28304-2 has Hyper
Speed Control architecture, which operates in fixed
3. Enable Input
frequency CCM mode under all load conditions.
The EN pin has an on board 100k pull-up resistor
(R16) to VIN, which allows the output to be turned on
The basic parameters of the evaluation board are:
when PVDD exceeds its UVLO threshold. An EN
Input: 7V to 70V
connector is provided on the evaluation board for
(1)
users to easily access the enable feature. Applying an
Output: 0.8V to 5V at 3A
external logic signal on the EN pin to pull it low or
600kHz Switching Frequency (Adjustable 200kHz
using a jumper to short the EN pin to GND will shut off
to 600kHz)
the output of the MIC28304 evaluation board.
Note:
4. Turn Power
1. Refer to temperature curves shown in the MIC28304 0.8V to 5V/3A
Evaluation Board Typical Characteristics section.
Turn on the VIN supply and verify that the output
voltage is regulated to 5V.
Datasheets and support documentation are available on
Micrels web site at: www.micrel.com.
Ordering Information
Requirements
Part Number Description
The MIC28304-1 and MIC28304-2 evaluation board
MIC28304-1 Evaluation
requires only a single power supply with at least 10A
MIC28304-1 5V EV
Board up to 5V Output
current capability. No external linear regulator is required
to power the internal biasing of the IC because the
MIC28304-2 Evaluation
MIC28304-2 5V EV
MIC28304 has internal PVDD LDO. In the applications Board up to 5V Output
with VIN < +5.5V, PVDD should be tied to VIN to bypass
MIC28304-1 Evaluation
MIC28304-1 12V EV
the internal linear regulator. The output load can either be
Board 12V Output
a passive or an active load.
MIC28304-2 Evaluation
MIC28304-2 12V EV
Precautions Board 12V Output
The MIC28304 evaluation board does not have reverse
polarity protection. Applying a negative voltage to the VIN
and GND terminals may damage the device. The
maximum VIN of the board is rated at 70V. Exceeding 70V
on the VIN could damage the device.
Hyper LightLoad is a registered trademark and Hyper Speed Control is a trademark of Micrel, Inc.
Micrel Inc. 2180 Fortune Drive San Jose, CA 95131 USA tel +1 (408) 944-0800 fax + 1 (408) 474-1000 Micrel, Inc. MIC28304 Evaluation Board
gives a 0.8V output voltage. All other voltages not listed
Features
above can be set by modifying R value according to:
BOTTOM
Feedback Resistors
R1 V
The output voltage on the MIC28304 evaluation board,
REF
Eq. 2
R =
BOTTOM
which is preset to 5.0V, is determined by the feedback V V
OUT REF
divider:
Note that the output voltage should not be set to exceed
R1 5V due to the 6.3V voltage rating on the output capacitors.
V = V 1 + Eq. 1
OUT REF
For higher output voltage, use the Ordering Information
R
BOTTOM
table. Table 1 gives the typical values of some of the
components, for details refer to Bill of Material table.
where V = 0.8V, and R is one of R10, or R11,
REF BOTTOM
which corresponds to 3.3V, 5V. Leaving the R open
BOTTOM
Table 1. Typical Values of Some Components
R1 R11
R3 C10 C12
V VIN (R ) (Top Feedback Resistor) (Bottom Feedback Resistor) (C ) (C ) C
OUT inj inj ff OUT
47F /6.3V
0.9V 5V to 70V 16.5k 10k 80.6k 0.1F 2.2nF
or 2 x 22F
47F /6.3V
1.2V 5V to 70V 16.5k 10k 20k 0.1F 2.2nF
or 2 x 22F
47F /6.3V
0.1F 2.2nF
1.8V 5V to 70V 16.5k 10k 8.06k
or 2 x 22F
47F /6.3V
0.1F 2.2nF
2.5V 5V to 70V 16.5k 10k 4.75k
or 2 x 22F
47F /6.3V
0.1F 2.2nF
3.3V 5V to 70V 16.5k 10k 3.24k
or 2 x 22F
47F/6.3V
5V 7V to 70V 16.5k 10k 1.9k 0.1F 2.2nF
or 2 x 22F
47F/16V
12V 18V to 70V 23.2k 10k 715 0.1F 2.2nF
or 2 x 22F
Revision 1.0
April 29, 2014 2