MIC69301/02 Evaluation Board
Low V
IN
, Low V
OUT
3A LDO Regulator
General Description
This evaluation board can be used to evaluate several of
Micrel’s new, low-voltage, high-current, low-dropout linear
voltage regulators. The MIC69301WR is a 3A LDO in an
SPAK package with a fixed output voltage that offers the
added functionality of an enable pin and an error flag
output. The MIC69302WR is an adjustable version of the
MIC69301WR in a SPAK package and it also has the
added functionality of an enable pin, allowing the user to
disable the device and put it into a zero-current off mode
state.
Requirements
The evaluation board requires a power supply capable of
supplying a minimum of 3A of output current. The
maximum voltage of that power supply should be at least
5V. The evaluation board has jumpers to set the output
voltage to: 3.3V, 2.5V, 1.8V or 1.5V. The output voltage
can also be set to a different value by using the adjustable
version (MIC69302) and by choosing R1 and R2 as
detailed on the right. The MIC69301 has an input voltage
range of 1.65V to 5.5V, therefore it is not limited to just 5V
systems.
Circuit Description
The MIC69301 regulator is simple to implement, requiring
only an output capacitor for proper operation. An input
capacitor is required when the supply is greater than 4
inch away from the device. The evaluation board includes
an input capacitor within 1 inch of the device. This is the
recommended maximum distance away from the device
that a capacitor should be placed.
A minimum of 10µF of output capacitance is required for
the MIC69301. Using large values of capacitance at the
input and output will help to improve transient response.
MIC69301/MIC69302
The MIC69301 circuit implements an error flag, an enable
function, and sense pin. The enable function allows the
user to put the device into a zero-current off state when
the regulator is not required. The enable pin is an active-
high pin and needs to be pulled high (≥2V) to enable the
device and pulled low (≤0.8V) to disable the device. The
error flag function is a voltage monitor that indicates when
the output falls out of regulation for any reason. The error
flag output is an open-collector output, which is active-low,
and requires a pull-up resistor for proper operation. R1 is a
zero ohm resistor. All berg jumpers on JP2 must be left
May 2008
open. Boards assembled with the MIC69301 have a
100kΩ pull-up resistor from FLG to the output voltage.
The MIC69302 is an adjustable regulator that implements
an enable pin that allows the user to disable the device.
The enable pin is also active-high and requires that pin to
be pulled high to turn-on the output and pulled low to
disable the output. A jumper (JP1) is available to tie that
pin to either the input or to ground. The output voltage of
the MIC69302 is adjustable down to 0.5V. The board is
set-up with four set voltage options, A through D. A fifth
option is available that can be custom set. The equation to
set the output voltage is as follows:
R1
⎞
⎛
V
OUT
=
V
REF
⎜
1
+
⎟
R2
⎠
⎝
V
REF
=
0.5V
On the board as it stands, R1 is set to 10kΩ. Using the
equation and knowing that R1 = 10kΩ, a custom voltage
can be determined by solving for R2 and placing an 0805
or 1206 resistor in the slot prepared and labeled E.
⎛
⎞
V
REF
R2
= ⎜
×
R1
⎟
⎜
V
⎟
⎝
OUT
−
V
RE
F
⎠
⎛
⎞
0.5V
R2
= ⎜
×
10k
Ω ⎟
⎜
V
⎟
⎝
OUT
−
0.5 V
⎠
Leaving all jumpers open sets the output voltage to 0.5V.
The MIC69302WR adjustable output evaluation board can
be configured into a fixed output version in the following
way:
R6 = 10kΩ
R1, R2, R3, R4, R5 Open
Remove all jumpers from JP2
Replace U1 with MIC69301WR
Minimum Load
All of the devices require a minimum load of 10mA. A
resistor is included on the board to provide a minimum
load of 10mA. The resistor value is different depending on
the voltage option that the board has. The MIC69301 has
a 140Ω resistor to maintain approximately 10mA at 1.4V
output voltage. The 140Ω resistor can be changed to set a
10mA load depending upon the desired output voltage.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-053008-A
Micrel, Inc.
MIC69301/02 Evaluation Board
Bill of Materials
Item
Part Number
C2012X5R0J106K
C1, C2
0805D106MAT2A
GRM21CR70J106KA01B
VJ0805Y106KXYAT
R1, R6
R2
R3
R4
R5
U1
Notes:
1. TDK: www.tdk.com
2. AVX: www.avx.com
3. Murata: www.murata.com
4. Vishay Dale: www.vishay.com
5. Micrel: www.micrel.com
Manufacturer
TDK
(1)
AVX
(2)
Murata
Vishay
(3)
(4)
Description
Qty
10µF/6.3V, X7R, Ceramic Capacitor
2
CRCW08051002FRT1
CRCW08054991FRT1
CRCW08053831FRT1
CRCW08052491FRT1
CRCW08051781FRT1
MIC69301WR
MIC69302WR
Vishay
(4)
Vishay
(4)
Vishay
(4)
Vishay
(4)
Vishay
(4)
10k, 1%, 1/10W, 0805 Resistor
4.99k, 1%, 1/10W, 0805Resistor
3.83k, 1%, 1/10W, 0805Resistor
2.49k, 1%, 1/10W, 0805Resistor
1.78k, 1%, 1/10W, 0805Resistor
Low V
IN
, Low V
OUT
3A LDO Regulator
2
1
1
1
1
1
Micrel
(5)
May 2008
3
M9999-053008-A
Micrel, Inc.
MIC69301/02 Evaluation Board
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its
use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2007 Micrel, Incorporated.
May 2008
5
M9999-053008-A
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