MIC49200 Evaluation Board

MIC49200 Evaluation Board
2.0A Low Voltage LDO Regulator
General Description
The demonstration board can be used to evaluate the
MIC49200. The MIC49200, a 2 amp, ultra-high speed, low
dropout linear regulator, utilizes a split supply input to
regulate low output voltages. It is offered in a low profile
S-pack. The MIC49200 is also offered in fixed and
adjustable outputs. Fixed output versions add enable pin
functionality, allowing it to be placed in a zero-current off
mode state. The adjustable version allows for the use of a
resistor divider network to adjust for the desired output
voltage. The evaluation board accommodates the
adjustable version.
Requirements
The MIC49200 requires two power supplies; one to
provide a minimum of 2A to the VIN and the other to
provide VBIAS current. Although typical VBIAS current is
40mA, in dropout conditions VBIAS currents can reach as
high as 270mA. The VBIAS supply should be able to supply
a minimum of 300mA. The VBIAS should be able to deliver
a minimum of 3V or 2.1V greater than VOUT, whichever is
greater. In cases where the VIN voltage satisfies the
minimum VBIAS voltage, one supply can be used.
Circuit Description
The MIC49200 ultra-high speed regulator is easy to use. It
is extremely tolerable to a wide range and types of output
capacitors. Although there is no minimum output capacitor
requirement for the MIC49200, a minimum 1µF capacitor
is recommended.
The evaluation board has a 10µF ceramic on the VIN pin.
Although this is much larger than required for the device,
this was designed to allow for the long inductive test leads
that will be attached to the evaluation board. The output
can be selected by using the evaluation board jumper. The
available output options on the evaluation board are 1.0V,
1.2V, 1.5V and 1.8V. Also, a 0.9V output can be obtained
by removing the jumper altogether. Any of the 4 bottom
feedback resistors can be substituted to obtain a different
output voltage. The equation to set the output is as follows:
⎛ R1 ⎞
VOUT = VREF ⎜
+ 1⎟
⎝ R2
⎠
VREF = 0.9
R1 on the evaluation board is set to 1KΩ. Due to the high
bandwidth of the MIC49200, larger values of R1 and the
parasitic capacitance of the feedback pin introduce an
additional pole. For R1 values greater than 1KΩ, a small
feed forward capacitor across R1 will be required to
maintain stability. Since R1 on the evaluation board is set
to 1K, the formula for adjusting the output to the desired
level is as follows:
⎛V
⎞
R2 = ⎜⎜ REF − VREF ⎟⎟ × R1
⎝ VOUT
⎠
⎛ 0.9V
⎞
R2 = ⎜⎜
− 0.9V ⎟⎟ × 1kΩ
⎝ VOUT
⎠
An input capacitor is required when the power supply is
more than 4” away from the device. All evaluation boards
include an input capacitor within 1” of the device. This is
the minimum recommended distance from the device that
the capacitor should be placed.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
February 2006
M9999-021306
(408) 955-1690
Micrel
MIC49200 Evaluation Board
MIC49200WR Circuit
Bill of Materials
MIC49200WR Evaluation Board
Item
C1, C2, C3
Part Number
GRM40X5R105K10
Manufacturer
TDK
(1)
Description
10µF, 6.3V capacitor
(2)
J1 – J5
2551200010000070
Millmax
JP1, JP2
S201204ND
Sullins(3)
R1, R5
CRCW06031001FRT1
Vishay(4)
CRCW06038871FRT1
Vihsay
(4)
8.87K, 1%, 1/16W, 0603 resistor
Vishay
(4)
2.87K, 1%, 1/16W, 0603 resistor
Vishay
(4)
1.5K, 1%, 1/16W, 0603 resistor
Vishay
(4)
R2
R3
R4
R6
U1
CRCW06032871FRT1
CRCW06031501FRT1
CRCW06031002FRT1
MIC49200WR
Qty.
1K, 1%, 1/16W, 0603 resistor
10K, 1%, 1/16W, 0603 resistor
(5)
Micrel, Inc.
2A, Low Voltage LDO with Dual Input
Notes:
1. TDK: www.tdk.com
2. Millmax: www.mill-max.com
3. Sullins: www.sullinselectronics.com
4. Vishay: www.vishay.com
5. Micrel, Inc.: www.micrel.com
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.
© 2006 Micrel, Incorporated.
February 2006
2
M9999-021306
(408) 955-1690