MIC4782 Evaluation Board

MIC4782 Evaluation Board
Dual 2A Buck Regulator
General Description
The Micrel MIC4782 is a high efficiency dual PWM buck
(step-down) regulator that provides up to 2A of output
current for each channel. The MIC4782 operates at
1.8MHz and has proprietary internal compensation that
allows a closed loop bandwidth of over 200kHz. The low
on resistance internal P-Channel MOSFET of the MIC4782
allows efficiencies up to 92%, reduces external component
count and eliminates the need for an expensive external
current sense resistor. The MIC4782 operates from a 3.0V
to 6.0V input and its output is adjustable down to 0.6V.
The devices can operate with a maximum duty cycle of
100% for use in low-dropout applications.
placed between the load and the VOUT1/VOUT2 terminal.
Ensure the output voltage is monitored at the
VOUT1/VOUT2 terminal. The default VOUT1 is set to 1.8V
and the default VOUT2 is set to 1.2V. This can be adjusted
by changing the feedback resistors. See “Output Voltage.”
3. Enable the MIC4782. The enable pins are connected to
pull up resistors. Both outputs of the MIC4782 turn on
when VIN exceeds the UVLO threshold at the VIN pin. Each
output of the MIC4782 may be turned off by shorting the
enable pin to ground or bringing the enable pin below the
enable threshold. An external connection on the board
provides easy access to the enable pin.
Output Voltage
Requirements
The MIC4782 evaluation board requires an input power
source that is able to deliver greater than 3.0V at over 4A.
The output load can either be an active or passive load.
The output voltages on the MIC4782 evaluation board are
adjustable. The output voltage is controlled by the
feedback resistors (R11 and R12 for VOUT1, R21 and R22
for VOUT2) and can be calculated as follows:
VOUT1 = VREF × (1 +
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the VIN terminal
may damage the device. In addition, the maximum
operating voltage of the MIC4782 evaluation board is 6.0V.
Exceeding 6.5V on the input could damage the device.
VOUT2 = VREF × (1 +
R21
)
R22
where VREF = 0.6V.
The evaluation board is preset at 1.8V for VOUT1 and 1.2V
for VOUT2, but can easily be modified by removing R12 or
R22 and replacing them with the value that yields the
desired output voltage.
Getting Started
1. Connect an external supply to VIN terminal. Apply
desired input voltage to the VIN and ground terminals of
the evaluation board, paying careful attention to polarity
and supply voltage (3.0V<VIN<6.0V). An ammeter may be
placed between the input supply and the VIN terminal to
the evaluation board. Ensure the supply voltage is
monitored at the VIN terminal. The ammeter and/or power
lead resistance can reduce the voltage supplied to the
input.
2. Connect the load to the VOUT1/VOUT2 and ground
terminals. The load can be either passive (resistive) or
active (as in an electronic load). An ammeter can be
R11
)
R12
R12 =
R11× VREF
VOUT1 − VREF
R22 =
R21× VREF
VOUT2 − VREF
For VREF = 0.6V, this reduces to:
R12 =
R11× 0.6 V
VOUT1 − 0.6 V
R22 =
R21× 0.6 V
VOUT2 − 0.6 V
MLF is a registered trademark of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
1
M9999-122209-A
Micrel, Inc.
MIC4782 Evaluation Board
Ordering Information
Part Number
MIC4782YML
MIC4782YML EV
Description
Package
IC
16-Pin MLF® EPAD
Evaluation Board
16-Pin MLF® EPAD
MLF is a registered trademark of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
2
M9999-122209-A
Micrel, Inc.
MIC4782 Evaluation Board
Bill of Materials
Item
Part Number
Manufacturer
Description
Qty
C11,C12
C21,C22
0805ZD106MAT2A
AVX(1)
10µF, Ceramic Capacitor, X5R, 0805, 10V
6
C15,C25
C13*,C23*
VJ0603A681KXXCW
Vishay(2)
680pF, Ceramic Capacitor, NP0, 0603, 25V
2
C14,C24
VJ0603A820KXXCW
Vishay
82pF, Ceramic Capacitor, NP0, 0603, 25V
2
VJ0603Y104KXXAT
Vishay
0.1µF, Ceramic, Capacitor, X7R, 0603, 25V
5
SS2P3L
Vishay
SSA23L
Vishay
2A Schottky, 30V
2
C16,C26,C7
C18,C28
D1,D2
B230A
L1,L2
IHLP2525AH-01 1R0
RLF7030-1R0 N
HCP0703-1R0
Diodes
(3)
Vishay
TDK
1µH Inductor, 17.5mΩ 6.86mm(L) x 6.47mm(W) x 1.8mm(H)
(4)
COOPER
CRCW060310K0FKXX
R12,R22
CRCW06033K16FKXX
3.16kΩ,1%, 0603 For 2.5VOUT
CRCW06034K99FKXX
4.99kΩ, 1%, 0603 For 1.8 VOUT
Vishay
2
1µH Inductor, 10mΩ 7.3mm(L) x 7.0mm(W) x 3.0mm(H)
R11,R21
CRCW06036K65FKXX
Vishay
1µH Inductor, 8.8mΩ 7.3mm(L) x 6.8mm(W) x 3.2mm(H)
(5)
10kΩ, 1%, 0603, resistor
2
6.65kΩ, 1%, 0603 For 1.5 VOUT
CRCW060310K0FKXX
10kΩ, 1%, 0603 For 1.2 VOUT
CRCW060315K0FKXX
15kΩ, 1%, 0603 For 1.0 VOUT
2
* only for ultra-low noise applications.
MLF is a registered trademark of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
3
M9999-122209-A
Micrel, Inc.
MIC4782 Evaluation Board
Item
Part Number
R13*, R23*
CRCW06032R70FKXX
Vishay
2.7Ω, 1%, 0603, resistor
2
R14, R24
CRCW060349K9FKXX
Vishay
49.9kΩ, 1%, 0603, resistor
2
R5
CRCW060310R0FKXX
Vishay
10Ω, 1%, 0603, resistor
1
Dual, 2A, 1.8MHz, Integrated Switch Buck Regulator
1
U1
MIC4782YML
Manufacturer
(6)
Micrel, Inc.
Description
Qty
Notes:
1.
AVX: www.avx.com
2.
Vishay: www.vishay.com
3.
Diodes: www.diodes.com
4.
TDK: www.tdk.com
5.
Cooper: www.cooperbussmann.com
6.
Micrel, Inc: www.micrel.com
* only for ultra-low noise applications.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
4
M9999-120209-A
Micrel, Inc.
MIC4782 Evaluation Board
Printed Circuit Board Layouts
Figure 1a. Top Layer
Figure 1b. Bottom Layer
MLF is a registered trademark of Amkor Technology.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
5
M9999-122209-A
Micrel, Inc.
MIC4782 Evaluation Board
Figure 1c. Mid-Layer 1 (GND Plane)
Figure 1d. Mid-Layer 2
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
6
M9999-120209-A
Micrel, Inc.
MIC4782 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.
© 2009 Micrel, Incorporated.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2009
7
M9999-120209-A