MIC33263/4 Evaluation Board
4MHz PWM 2A Buck Regulator with
Integrated Inductor and HLL
®
Technology
General Descr i ption
The MIC33263/4 evaluation board allows the customer to
evaluate a fully-integrated MOSFETs & Induc tor 2A, 4MHz
synchronous buck regulator that features HyperLight
Load® mode, a Power Good output indicator, and
programmable soft-start. The MIC33263/4 is highly
efficient throughout the output current range. The tiny
2.5mm x 3mm QFN package, in combination with the
4MHz switching frequency, provides a compact sub-
1.9mm height solution and 7mm x 4.6mm total solution
size that requires few external components.
The MIC33263/4 has a maximum 100% duty cycle, and
the MIC33264 also incorporates an active discharge
feature when disabled. It provides accurate output voltage
regulation under the most demanding conditions and
responds extremely quickly to a load transient with
exceptionally small output voltage ripple.
Requirements
The MIC33263/4 evaluation board requires a single 15W
bench power source adjustable from 2.7V to 5.5V. The
loads can either be active (electronic load) or passive
(resistor), and must be able to dissipate 10W. It is ideal,
but not essential, to have an oscilloscope available to view
the circuit waveforms. The simplest tests require two
voltage meters to measure input and output voltages.
Efficiency measurements require two voltage meters and
two ammeters to prevent errors caused by measurement
inaccuracies.
Precautions
There is no reverse input protection on this board. Be
careful when connecting the input source to ensure correct
polarity is observed.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Getting Started
1. Connect an external supply to the VIN (J1) and GND
(J2) terminals.
With the output of the power supply disabled, set its
voltage to the desired input test voltage (2.7V ≤ VIN ≤
5.5V). An ammeter may be placed between the input
supply and the VIN (J1) terminal. Be sure to monitor
the supply voltage at the VIN (J1) terminal , as t he
ammeter and/or pow er lead resistance can reduce the
voltage supplied t o t he device.
2. Connect a load to the VOUT (J3) and GND (J4)
terminals.
The load can be either p assive (resistive) or act i ve
(electronic load). A n am meter may be placed bet ween
the load and the output terminal. Make sure the output
voltage is monitored at the VOUT (J3) terminal.
3. Enable the MIC33263/4.
The MIC33263/4 evaluation board has a pull-up
resistor (R3) to VIN. By default, the output voltage is
enabled when the i nput supply of >2.7V is applied. To
disable the device, apply a voltage below 0.5V to the
EN (J6) terminal.
4. Power Good.
A PG test point (J5) is provided to monitor the Power
Good feature. The Power Good o utput will go high
(VOUT) approximately 90µs after the output vol tage
reaches 92% of its nominal voltage.
Ordering I nfor m ati on
Part Number Description
MIC33263YGK EV MIC33263 Evaluation Board
MIC33264YGK EV MIC33264 Evaluation Board
HyperLight Load is a registered trademark of Micrel, Inc.
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 6, 2014 Revision 1.0
Micrel, Inc.
MIC33263/4 E valuation Board
Evaluation Board
Features
Soft-Start Capacitor (C 3)
The soft start (SS) pin is used to control the output voltage
ramp-up time. Setting C3 to 1nF sets the start-up time to
the minimum. The start-up time can be determined by
Equation 1:
SS
3
SS
C)10ln(10250T×××=
Eq. 1
The action of the soft-start capacitor is to control the rise
time of the internal reference voltage between 0% and
100% of its nominal steady-state value.
Feedback Resistors (R1, R2)
The output voltage of the evaluation board is set to 2V.
This output can be changed by adjusting the upper
resistor, R1, in the feedback potential divider. The output
voltage can be programmed between 0.7V and 5V using:
+×
=R2
R1
1
VV REF
OUT
Where VREF = 0.7V
Table 1. Examp le Feedback Resistor Values
VOUT
R1
R2
1.2V 215k 301k
1.5V 301k 261k
1.8V 340k 215k
2.5V 274k 107k
3.3V 383k 102k
5V 634k 102k
The feedforward capacitor, C4, provides essential
compensation for the MIC33263/4. A typical value range of
15pF to 68pF is recomm ended.
Power Good (PG)
The evaluation board has a test point provided for testing
the Power Good feature. This is an open-drain connection
with an on-board pull-up resistor of 100kΩ (R4) to the
output voltage. Power Good is asserted high
approximately 90µs after the output voltage passes 92% of
the nominal set voltage.
HyperLight Load Mode
MIC33263/4 uses a minimum on and off time proprietary
control loop (patented by Micrel). When the output voltage
falls below the regulation threshold, the error comparator
begins a switching cycle that turns the PMOS on and
keeps it on for the duration of the minimum-on-time. This
increases the output voltage. If the output voltage is more
than the regulation threshold, then the error comparator
turns the PMOS off for a minimum-off-time until the output
drops below the threshold. The NMOS acts as an ideal
rectifier that conducts when the PMOS is off. Using an
NMOS switch instead of a diode allows for lower voltage
drop across the switching device when the NMOS is on.
The asynchronous switching combination between the
PMOS and the NMOS allows the control loop to work in
discontinuous mode for light load operations. In
discontinuous mode, the MIC33263/4 works in pulse
frequency modulation (PFM) to regulate the output. As the
output current increases, the off-time decreases. This
provides more energy to the output. This switching
scheme improves the efficiency of MIC33263/4 during light
load currents by only switching when it is needed.
As the load current increases, the MIC33263/4 goes into
continuous conduction mode (CCM) and switches at a
frequency centered at 4MHz.
May 6, 2014 2 Revision 1.0
Micrel, Inc.
MIC33263/4 E valuation Board
Evaluation Board S chematic
Bill of Materials
Item
Part Number
Manufacturer
Description
Qty.
C1 C1608X5R1A475K080AC TDK(1) 4.7µF, 10V, X5R, Size 0603 1
GRM188R60J475KE19D Murata(2)
C2 C1608X5R1A105K TDK 1µF, 10V, X5R, Size 0603 1
C3 C1005C0G1H102J050BA TDK 1nF, 50V, 0402 1
C4
C1005C0G1H150J050BA TDK
15pF, 50V, 0402 1
GRM1555C1H150JZ01D Murata
C5 C1608X5R1A226M080AC TDK 22µF,10V, X5R, Size 0603 1
C6 C1608X7R1A104K TDK 0.1µF,10V, X7 R , Size 0603 1
R1 CRCW0402301KFKEA Vishay(3) 301kΩ, 1%, 1/16W, Size 0402 1
R2 CRCW0402158K0FKEA Vishay 158kΩ, 1%, 1/16W, Size 040 2 1
R3, R4 CRCW0402100KFKEA Vishay 100kΩ, 1%, 1/16W, Size 0402 2
R5 CRCW040249R9FKED Vishay 49.9Ω, 1%, 1/16W, Size 0402 1
U1 MIC33163YGK Micrel, Inc.(4) 4MHz, 2A, 100% Duty C ycle Buck Regulator with
Integrated Inductor and H yperLight Load Technology 1
MIC33164YGK
Notes:
1. TDK: www.tdk.com.
2. Murata: www.murata.com.
3. Vishay: www.vishay.com.
4. Micrel, Inc.: www.micrel.com.
May 6, 2014 3 Revision 1.0
Micrel, Inc.
MIC33263/4 E valuation Board
PCB Layout
Top Layer
Bottom Layer
May 6, 2014 4 Revision 1.0
Micrel, Inc.
MIC33263/4 E valuation 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
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right.
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 t
o 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 a
nd Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2014 Micrel, Incorporated.
May 6, 2014 5 Revision 1.0
