MIC2619 Evaluation Board
1.2MHz PWM Boost Converter
with OVP
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
March 2010 M9999-030210-A
General Description
The MIC2619 is a 1.2MHz pulse width modulated (PWM)
step-up switching regulator that is optimized for low power,
high output voltage applications. With a maximum output
voltage of 35V and a switch current of over 350mA, the
MIC2619 can easily supply most high voltage bias
applications, such as TV tuners.
The MIC2619 implements a constant frequency 1.2MHz
PWM current-mode control scheme. The high frequency
PWM operation saves board space by reducing external
component sizes. The additional benefit of the constant
frequency PWM control scheme as opposed to variable
frequency control schemes is lower output noise and
smaller input ripple injected back to the power source. The
MIC2619 has programmable overvoltage protection to
ensure output protection in case of fault condition.
Requirements
The MIC2619 Evaluation board requires a single 1W
bench power source adjustable from 2.8V to 6.5V. The
load can either be active (electronic load) or passive
(resistor) with the capability to dissipate 0.7W. It is ideal to
have an oscilloscope available to view the circuit
waveforms, but not essential. For the simplest test, two
voltage meters are required to measure input and output
voltage. For efficiency measurements, two voltage meters
and two ammeters are required to prevent errors due to
measurement inaccuracies.
Precautions
The evaluation board does not have input reverse polarity
protection. Be cautious when connecting the input source
to ensure correct polarity is observed.
Getting Started
1. Connect an external supply to the VIN (J1)
terminal and GND (J2). With the output of
the power supply disabled, set its voltage to
the desired input test voltage (2.8V ≤ VIN ≤
6.5V). An ammeter may be placed between
the power supply and the VIN (J1) terminal of
the evaluation board. Be sure to monitor the
supply voltage at the VIN (J1) terminal, as the
ammeter and/or power lead resistance can
reduce the voltage supplied to the input.
2. Connect a load to the VOUT (J4) and GND
pins (J5) terminals. The load can be either
passive (resistor) or active (electronic load).
An ammeter may be placed between the load
and output terminal. Be sure to monitor the
output voltage at the VOUT (J4) terminal.
3. Enable/Disable the MIC2619. The MIC2619
evaluation board has a pull-down resistor to
GND. By default the MIC2619 will be disabled
and the output voltage will be approximately
VIN. By placing a jumper at JP1, the enable
pin is tied directly to VIN and the output
voltage will be enabled when the input supply
of ≥2.8V is applied.
4. Over-Voltage Protection (OVP). The
MIC2619 evaluation board uses a resistor
divider network (R1 and R2) to set the OVP
voltage. The default OVP voltage of the
evaluation board is 35V. Please see the
“Additional Information” section for instructions
to externally adjust the OVP voltage.
Ordering Information
Part Number Description
MIC2619YD6 EV Evaluation Board with
MIC2619YD6 Device
Micrel, Inc. MIC2619 Evaluation Board
March 2010 2 M9999-030210-A
Evaluation Board Schematic
Bill of Materials
Item Part Number Manufacturer Description Qty.
C1608X5R1A105K TDK(1) Capacitor, 1.0µF, 10V, X5R, 0603 size
GRM185R61A105KE36D Murata(2) Capacitor, 1.0µF, 10V, X5R, 0603 size
C1
0603ZD105KT2A AVX(3) Capacitor, 1.0µF, 10V, X5R, 0603 size
1
C2 TAJA106M010R AVX Capacitor, 10.0µF, 10V, A Case 1
C1608X7R11H223K TDK Capacitor, 22nF, 50V, X7R, 0603 size
GRM188R71H223KA01D Murata Capacitor, 22nF, 50V, X7R, 0603 size
C3
06035C223JAT2A AVX Capacitor, 22nF, 50V, X7R, 0603 size
1
08055D105MAT2A AVX Capacitor, 1.0µF, 50V, X5R, 0805 size
GRM21BR71H105KA12L Murata Capacitor, 1.0µF, 50V, X5R, 0805 size
C4
CL21B105KBFNNNE Samsung(4) Capacitor, 1.0µF, 50V, X7R, 0805 size
1
SK14 MCC(5) Schottky Diode, 1A, 40V D1
B140/B Diode, Inc.(6) Schottky Diode, 1A, 40V 1
C1G22L100MNE Samsung Inductor, 10.0µH, 0.8A, 2.5 x 2.0 x 1.0mm
VLF3012ST-100MR59 TDK Inductor, 10.0µH, 0.59A, 2.8 x 3.0 x 1.2mm
L1
LQH32PN100MN0L Murata Inductor, 10.0µH, 0.7A, 3.2 x 2.5 x 1.55mm
1
R1 CRCW0603267KFKEA Vishay(7) Resistor, 267kΩ, 1%, 1/16W, 0603 size 1
R2, R5 CRCW060310K0FKEA Vishay Resistor, 10kΩ, 1%, 1/16W, 0603 size 2
R3 CRCW0603100KFKEA Vishay Resistor, 100kΩ, 1%, 1/16W, 0603 size 1
R4 CRCW0603226KFKEA Vishay Resistor, 226kΩ, 1%, 1/16W, 0603 size 1
U1 MIC2619YD6 Micrel, Inc.(8) 1.2MHz PWM Boost Converter with OVP 1
Notes:
1. TDK: www.tdk.com
2. Murata: www.murata.com
3. AVX: www.avx.com
4. Samsung: www.sem.samsung.com
5. MCC: www.mccsemi.com
6. Diode, Inc.: www.diodes.com
7. Vishay: www.vishay.com
8. Micrel, Inc.: www.micrel.com
Micrel, Inc. MIC2619 Evaluation Board
March 2010 3 M9999-030210-A
PCB Layout Recommendations
Top Layer
Bottom Layer
Micrel, Inc. MIC2619 Evaluation Board
March 2010 4 M9999-030210-A
Additional Information
Ripple Measurements
To properly measure voltage ripple on either the input or
output of any regulator with a switching regulator near
by, a proper ring in tip measurement is required.
Standard oscilliscope probes come with a grounding clip,
or a long wire with an alligator clip. Unfortunately, for
high frequency measurements, this ground clip can pick
up high frequency noise and erroneously inject it into the
measured output ripple.
The MIC2619 evaluation boards accommodate a home
made ring in tip measurement by probing across input
and output capacitors. This requires the removing of the
oscilloscope probe sheath and ground clip from a
standard oscilloscope probe and wrapping a non-
shielded bus wire around the oscilloscope probe (as
shown on the left). If there does not happen to be any
non-shielded bus wire immediately available, the leads
from axial resistors will work. By maintaining the
shortest possible ground lengths on the oscilloscope
probe, true ripple measurements can be obtained.
Micrel, Inc. MIC2619 Evaluation Board
March 2010 5 M9999-030210-A
Feedback resistors
The MIC2619 utilizes a feedback pin to compare the
output to an internal reference. The output voltage is
adjusted by selecting the appropriate feedback resistor
network values. The desired output voltage can be
calculated as follows:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+×= 1
R
R
265.1V
2
1
OUT
Over-Voltage Protection (OVP)
The OVP pin provides over-voltage protection on the
output of the MIC2619. When the OVP circuit is tripped,
the output voltage remains at the set OVP voltage.
Because the OVP circuit operates at a lower frequency
than the feedback circuit, output ripple will be higher
while in an OVP state. OVP requires a resistor divider
network to the output and GND to set the OVP voltage. If
the output voltage overshoots the set OVP voltage, the
MIC2619 OVP circuit will shut off the switch; saving itself
and other sensitive circuitry downstream. The accuracy
of the OVP pin is ±5% and therefore, should be set
above the output voltage to ensure noise or other
variations will not cause a false triggering of the OVP
circuit. Caution should be exercised to not exceed the
35V rating of the output voltage.
To set the OVP voltage, replace the R1 and R2 resistor
values on the evaluation board with the calculated
values using the following equation:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+×
=1
R
R
265.1
2
1
OVP
V
VOUT or VOVP (V) R3 (kΩ) R6 (kΩ)
5.0 29.4 10
8.0 53.6 10
10 69.8 10
12 84.5 10
15 107 10
18 133 10
20 147 10
25 187 10
30 226 10
35 267 10
Table 1. VOUT or OVP Example Resistor Va
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 acurate 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.
© 2010 Micrel, Incorporated.
