MIC2169A Evaluation Board
500kHz MSOP-10 Synchronous
Step-Down Controller
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 2007
1
M9999-053107-A
General Description
The MIC2169A is a high-efficiency, simple to use 500kHz
PWM synchronous buck control IC housed in a small
MSOP-10 package. The MIC2169A allows compact DC-to-
DC solutions with a minimal external component count and
cost. The output voltage can be precisely regulated down
to 0.8V. The adaptive all N-Channel MOSFET drive
scheme allows efficiencies over 95% across a wide load
range.
Note: This evaluation board is for 3A applications. A 7A
output evaluation board is also available. The literature for
the 7A evaluation can be found in the MIC2169A data
sheet.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Requirements
The MIC2169A evaluation board requires an input power
source that is able to deliver greater than 3A at 12V.
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the V
IN
(J1)
terminal may damage the device.
The MIC2169A evaluation board is tailored for a 5V to 12V
input voltage range. The input voltage range should not
exceed 14.5V on the input.
Getting Started
1.
Connect an external supply to the VIN
. Apply
desired input voltage to the V
IN
(J1) and ground
(J2) terminals of the evaluation board, paying
careful attention to polarity and supply voltage
(5V
≤
V
IN
≤
12V). An ammeter may be placed
between the input supply and the V
IN
terminal to
the evaluation board. Ensure that the supply
voltage is monitored at the V
IN
terminal. The
ammeter and/or power lead resistance can reduce
the voltage supplied to the input.
2.
Enabling the MIC2169A
. The MIC2169A is
enabled as soon as a power supply with a voltage
in the range of 3V to 14.5V is connected across
the V
IN
(J1) and GND (J2) terminals.
Adjusting Output Voltage
The output voltage on the MIC2169A evaluation board is
adjustable. The output voltage is controlled by the
feedback resistors (R1 and R2) and can be calculated as
follows:
⎟
⎠
⎞
⎜
⎝
⎛
+
=
1
3
2
8
.
0
R
R
V
V
OUT
The evaluation board is initially adjusted to 1.5V, but can
easily be modified by removing R3 and replacing it with the
value that yields the desired output voltage. The R2
resistor is recommended for a 3k
Ω
to 10k
Ω
resistor range.
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
−
Ω
=
V
V
V
k
R
OUT
8
.
0
8
.
0
10
3
Ensure the output voltage selected does not exceed 5V,
since the tantalum output capacitor has a 6.3V voltage
rating. Typically the working voltage for tantalum
capacitors should never exceed 80% of their rated voltage
value. When output voltages greater than 5V are desired,
the output capacitor should be replaced with one where
the output voltage is less than 80% of the output capacitor
voltage rating (tantalum capacitors).
Ordering Information
Part Number
Description
Package
MIC2169AYMM IC
10-Pin
MSOP
MIC2169A Tiny3A EV
Evaluation Board
10-Pin MSOP
