General Description
The MAX15020 evaluation kit (EV kit) is a fully assembled
and tested PCB that evaluates the MAX15020 PWM
step-down regulator IC with an integrated high-side
switch. The MAX15020 is equipped with a reference
input for the feedback error amplifier, allowing dynamic
output-voltage programming. The MAX15020 EV kit
operates over a wide input-voltage range of 7.5V to 40V
and provides up to 2A.
The MAX15020 internal switching frequency can be set
to either 300kHz or 500kHz. The MAX15020 EV kit fea-
tures a SYNC input to provide external frequency syn-
chronization for sensitive applications. The EV kit uses a
MAX15020 step-down regulator in a 20-pin thin QFN
package. The MAX15020 IC operates over the automo-
tive temperature range of -40°C to +125°C and is suit-
able for printers, industrial, and automotive applications.
Features
oWide 7.5V to 40V Input Range
oDynamic Output-Voltage Control from 0.8V to 36V
with 2A Load
oSelectable 300kHz/500kHz Switching Frequency
oTurn-On/Off Control
oDemonstrates MAX15020 IC Low Shutdown
Current
oHigh Efficiency up to 96% (VIN = 36V, VOUT = 30V,
ILOAD = 2A)
oDemonstrates MAX15020 IC Over-Current and
Thermal Protection
oSpace-Saving 5mm x 5mm, 20-pin TQFN Package
oFully Assembled and Tested
Evaluates: MAX15020
MAX15020 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-0804; Rev 2; 6/08
Component List
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
PART TYPE
MAX15020EVKIT+ EV Kit
+
Denotes lead-free and RoHS compliant.
DESIGNATION QTY DESCRIPTION
C1, C6 2
560µF ±20%, 50V low ESR
electrolytic capacitors
(12.5mm x 25mm)
SANYO 50ME560WX
C2, C4, C10 3
1µF ±10%, 25V X7R ceramic
capacitors (0805)
TDK C2012X7R1E105K
C3, C5, C7, C9 4
0.1µF ±10%, 50V X7R ceramic
capacitors (0603)
TDK C1608X7R1H104K
C8 1
0.22µF ±10%, 50V X7R ceramic
capacitor (0805)
Murata GRM21BR71H224K
C11 1
0.027µF ±10%, 50V X7R ceramic
capacitor (0603)
AVX 06035C273KAT2A
C12 1
0.1µF ±10%, 50V X7R ceramic
capacitor (0805)
TDK C2012X7R1H104K
C13 1
330pF ±5%, 50V C0G ceramic
capacitor (0603)
TDK C1608C0G1H331J
DESIGNATION QTY DESCRIPTION
D1 1 60V, 3A Schottky diode (SMA)
Diodes Inc. B360A
D2 1 100V, 150mA Schottky diode
(SOD-123) Vishay BAT46W
JU1, JU2, JU3 3 3-pin headers
L1 1 22µH, 4.7A inductor
Sumida CDRH127/LDNP-220MC
R1 1 97.6kΩ ±1% resistor (0603)
R2 1 4.02kΩ ±1% resistor (0603)
R3, R4 2 10kΩ ±5% resistors (0603)
R5 1 10Ω ±5% resistor (0603)
R6, R7 2 10kΩ ±1% resistors (0603)
R8 1 340Ω ±1% resistor (0603)
R9 1 15.8kΩ ±1% resistor (0603)
R10 1 0Ω ±5% resistor (0603)
R11 1 20kΩ ±1% resistor (0603)
TP1–TP4 4 PC mini red test points
U1 1 MAX15020ATP+
20-pin TQFN (5mm x 5mm x 0.8mm)
— 3 Shunts (JU1, JU2, JU3)
— 1 PCB: MAX15020 Evaluation Kit+
Evaluates: MAX15020
MAX15020 Evaluation Kit
2 _______________________________________________________________________________________
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• 7.5V to 40V adjustable, 3A power supply
•15Ωresistive load rated for 75W or greater
• Two digital voltmeters
Procedure
The MAX15020 EV kit is fully assembled and tested.
Follow these steps to verify board operation. Caution:
Do not turn on the power supply until all connec-
tions are completed.
1) Verify that a shunt is not installed at jumper JU1
(default 32V turn-on voltage).
2) Verify that shunts are installed on pins 1-2 of
jumpers JU2 (REFIN = REFOUT) and JU3 (300kHz
switching frequency).
3) Connect the resistive load between the OUT PCB
pad and the PGND PCB pad.
4) Connect digital voltmeters across the IN and PGND
pads, and the OUT and PGND pads on the EV kit
board.
5) Connect the power supply’s positive terminal to the
IN PCB pad on the EV kit, and connect the power-
supply ground terminal to the PGND PCB pad.
6) Turn on the power supply.
7) Set the power-supply voltage to 36V.
8) Verify that the voltmeter at OUT measures 30V.
Detailed Description of Hardware
The MAX15020 EV kit circuit uses a MAX15020 step-
down regulator IC (U1) to implement a step-down DC-
DC regulator circuit. The EV kit operates over a 7.5V to
40V input range. The circuit provides a dynamically pro-
grammable output range of 0.8V to 36V and can deliver
up to 2A of current with excellent line and load regula-
tion. The MAX15020 step-down regulator features an
internal high-side-low RDS(ON) MOSFET to achieve high-
er efficiency and lower overall system cost. The
MAX15020 also features configurable soft-start, shut-
down control, cycle-by-cycle current limit, hiccup-mode
output short-circuit protection, and thermal shutdown.
The undervoltage lockout (UVLO) threshold is config-
urable by choosing the appropriate R1 and R2 resistors.
The MAX15020 EV kit features a selectable 300kHz or
500kHz switching-frequency operation, in addition to a
SYNC input that can be used to synchronize the
MAX15020 to frequencies operating in the 300kHz to
500kHz range. An external reference input (REFIN_EXT)
is available to dynamically change the output voltage.
Jumper Selection
ON/OFF Mode
The MAX15020 EV kit features a ON/OFF mode that
reduces the MAX15020 supply current to 6µA (typ). The
3-pin jumper JU1 selects the ON/OFF mode for the
MAX15020 EV kit. See Table 1 for jumper JU1
configurations.
REFIN_EXT Input
The MAX15020 features a reference input for the inter-
nal error amplifier. The voltage applied to REFIN_EXT
PCB pad is used to dynamically change the circuit’s
output voltage. Jumper JU2 connects REFIN to
REFOUT to use the MAX15020’s 1V internal reference
voltage. See Table 2 for jumper JU2 configurations. To
change the MAX15020 EV kit output voltage using
REFIN_EXT, refer to the
Setting the Output Voltage
sec-
tion in the MAX15020 IC data sheet.
Component Suppliers
SUPPLIER PHONE WEBSITE
AVX Corp. 843-448-9411 www.avxcorp.com
Diodes Inc. 805-446-4800 www.diodes.com
Murata 770-436-1300 www.murata.com
SANYO 619-661-6835 www.sanyodevice.com
Sumida Corp. 847-545-6700 www.sumida.com
TDK Corp. 847-803-6100 www.component.tdk.com
Vishay 203-268-6261 www.vishay.com
Note: Indicate that you are using the MAX15020 when contacting
these component suppliers.
Table 1. Jumper JU1 ON/OOFFFFMode
SHUNT
LOCATION
ON/OFF PIN
MAX15020 OUTPUT
1-2
Connects to VIN directly
MAX15020 enabled
2-3 Connects to GND MAX15020 disabled
None* C onnects to V
I N
thr oug h
R1 and R2 r esi stor s
MAX15020 enabled at
VIN ≅ 32V
*
Default position.
Table 2. Jumper JU2 Reference-Voltage
Input
SHUNT
LOCATION
REFIN PIN VOUT
1-2* Connects directly to
REFOUT 30V
2-3 Externally controlled by
REFIN_EXT voltage
Dependent on voltage
at REFIN_EXT
*
Default position.
Frequency Selection
Jumper JU3 selects the MAX15020 operating switching
frequency between 300kHz or 500kHz. See Table 3 for
switching frequency selection.
Configuring the Output Voltage (OUT)
The MAX15020 EV kit step-down regulator output volt-
age is configured to 30V by resistors R7 and R8, and
with REFIN = REFOUT. The EV kit’s output voltage
(OUT) can be reconfigured in the range of 0.8V to 36V
by replacing resistors R7 and R8. To select a new value
for resistor R8, refer to the
Compensation Design
sec-
tion in the MAX15020 IC data sheet. Use the following
equation to reconfigure the output voltage to the
desired value:
where VOUT is the desired output voltage in volts,
VREFIN is the voltage supplied by REFOUT or
REFIN_EXT, and R7 is typically 10kΩ.
The MAX15020 output voltage can also be adjusted
dynamically by driving REFIN_EXT between 0 and
3.6V. To use the REFIN_EXT input, place a shunt
across pins 2-3 of jumper JU2.
Reconfiguring the MAX15020 EV kit for a new output
voltage may require replacing inductor L1 and capaci-
tors C1 and/or C6 . To select a new value for inductor
L1 and capacitors C1 and C6, refer to the
Inductor
Selection
,
Output Capacitor Selection,
and
Input
Capacitor Selection
sections, respectively, in the
MAX15020 IC data sheet.
Configuring the ON/
OFF
Threshold
The MAX15020 EV kit turn-on threshold is configured to
32V with resistors R1 and R2. The MAX15020 turns on
when the input voltage (VIN) is approximately above
32V and ON/OFF is ≥1.23V. The ON/OFF threshold can
be reconfigured to a desired value by appropriately
selecting resistors R1 and R2. Refer to
Setting the
ON/OFF Threshold
section in the MAX15020 IC data
sheet. To reconfigure the UVLO threshold, use the fol-
lowing equation:
where resistor R1 should be in the range of 100kΩand
VUVLO is the desired UVLO threshold in volts.
Place a shunt across pins 1-2 of jumper JU1 for always-
on operation, which bypasses the on/off threshold.
Resistor R11 is utilized to prevent excessive power dis-
sipation in resistor R2 when the shunt at jumper JU1 is
installed on pins 1-2.
Synchronization Input (SYNC)
The MAX15020 EV kit circuit features a selectable
300kHz or 500kHz switching frequency. Jumper JU3
sets the internal switching frequency. The EV kit’s SYNC
PCB pad can be used to synchronize the MAX15020
with an external digital clock in the range of 300kHz to
500kHz. When SYNC is driven with an external digital
clock, the MAX15020 synchronizes to the rising edge of
the external clock.
The digital square-wave clock source must provide the
following signal qualities:
• Output voltage: Logic-low = 0 to 0.8V, logic-high =
2V to 5.5V
• Input frequency = 300kHz to 500kHz (refer to the
MAX15020 IC data sheet for more information on
the SYNC input)
• Minimum pulse width = 200ns
To use external synchronization, connect the external
square-wave clock to the SYNC and GND pads.
RR VUVLO
12 123 1=× −
⎡
⎣
⎢⎤
⎦
⎥
.
RR
V
V
OUT
REFIN
87
1
=
−
⎡
⎣
⎢⎤
⎦
⎥
Evaluates: MAX15020
MAX15020 Evaluation Kit
_______________________________________________________________________________________ 3
Table 3. Jumper JU3 Frequency Selection
*Default position.
When operating the MAX15020 with an exter-
nal clock signal at SYNC, place the shunt on pins 1-2. Refer to
the
Oscillator/Sychronization Input
section of the MAX15020 IC
data sheet for more information.
SHUNT
LOCATION
FSEL PIN MAX15020 SWITCHING
FREQUENCY
1-2* Connects to VREG 300kHz
2-3 Connects to GND 500kHz
Evaluates: MAX15020
MAX15020 Evaluation Kit
4 _______________________________________________________________________________________
MAX15020
U1
L1
22µH
TP4
TP3
D1
D2
15
1617181920
1
1
14
13
12
11
LX
VIN
VIN
VIN
GND VREG
COMP
LX
LX
BST
N.C.
FB
R7
10kΩ
1%
R9
15.8kΩ
1%
R6
10kΩ
1%
R10
0Ω
R8
340Ω
1%
C11
0.027µF
C4
1µF
C3
0.1µF
50V
C1
560µF
50V
R11
20kΩ
1%
R1
97.6kΩ
1%
R2
4.02kΩ
1% C5
0.1µF
50V
C9
0.1µF
50V
C8
0.22µF
R3
10kΩ
R4
10kΩ
C10
1µF
R5
10Ω
C2
1µF
VREG
COMP
2
2
FB
3
3
1
1
2
2
3
3
ON/OFF
4REFOUT
REFIN
5
6
FSEL SYNC PGNDNDVREG
VREG
78 9 10
CSS
FB
REFOUT
JU2
JU3
JU1
REFOUT
TP1
TP2
SYNC
IN
PGND
GND
REFIN_EXT
ON/OFF
C12
0.1µF
C13
330pF
PGND
OUT
C7
0.1µF
50V
C6
560µF
50V
COMP
Figure 1. MAX15020 EV Kit Schematic
Evaluates: MAX15020
MAX15020 Evaluation Kit
_______________________________________________________________________________________ 5
Figure 2. MAX15020 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX15020 EV Kit PCB Layout—Component Side
Evaluates: MAX15020
MAX15020 Evaluation Kit
6 _______________________________________________________________________________________
Figure 4. MAX15020 EV Kit PCB Layout—GND Layer 2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________
7
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX15020
MAX15020 Evaluation Kit
Revision History
REVISION
NUMBER
REVISION
DATE REVISION DESCRIPTION PAGES
CHANGED
0 4/07 Initial release —
1 11/07 Updated Ordering Information table format; corrections to Procedures (step 2),
Configuring ON/
OFF
Threshold, and Figure 1. 1–4
2 6/08 Changed part number for C13 in Component List.1
