19-0314; Rev. 0; 10/94
MAX747 Evaluation Kit
_______________General Description
The MAX747 evaluation kit (EV kit) provides a regulated
5.0V output voltage from a 6V to 15V input. It delivers a
1.25A output current and up to 95% efficiency from a 6V
supply using small, surface-mount components.
___________________________Features
o
6.0V to 15.0V Input Voltage Range
o
Fixed 5V or Optional Adjustable Output Voltage
o
1.25A Output Current Capability
o
Up to 95% Efficiency
o
PWM Architecture
o
External Shutdown Control
o
Fully Assembled and Tested
Evaluates: MAX747
______________Ordering Information
PART
MAX747EVKIT-SO
TEMP. RANGE
0°C to +70°C
BOARD TYPE
Surface Mount
____________________Component List
DESIGNATION
C3, C4
C5
C6
QTY
2
1
1
DESCRIPTION
0.1µF ceramic capacitors
0.22µF ceramic capacitor
470pF ceramic capacitor
220µF, 10V, low-ESR
tantalum capacitors
AVX TPSE227M010R0100 or
Sprague 595D227X0010R2T
68µF, 20V, low-ESR
tantalum capacitors
AVX TPSE686M020R0150 or
Sprague 595D686X0020R2T
3A, 20V Schottky diode (SMT)
Nihon NSQ03A02,
Motorola MBRS340T3 or
IR30BQ040
33µH, 1.8A inductor (SMT)
Sumida CDR125-330,
CoilCraft D03316-333
P-channel MOSFET (SO-8)
Motorola MMSF3P02HD,
Siliconix Si9430DY or
IRF7204
0.068Ω, 5% resistor (SMT)
Dale WSL-2010-R068-J or
IRC LR2010-05-R068-J
MAX747CSD
3-pin header
Shunt
MAX747 data sheet
C1, C8
2
______________________________EV Kit
C2, C7
2
D1
1
L1
1
P1
1
R6
U1
JU1
None
None
1
1
1
1
1
________________________________________________________________ Maxim Integrated Products
1
Call toll free 1-800-998-8800 for free samples or literature.
MAX747 Evaluation Kit
Evaluates: MAX747
______________Component Suppliers
SUPPLIER
Capacitors
AVX
Matsuo
Murata Erie
Sprague
Inductors
CoilCraft
Coiltronics
Sumida
Diodes
Central
Semiconductor
Motorola
Nihon
Power MOSFETs
IR
Motorola
Siliconix
Resistors
Dale-Vishay
IRC
(402) 564-3131
(512) 992-7900
(402) 563-1841
(512) 992-3377
(310) 322-3331
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(408) 988-8000
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(602) 244-4015
(408) 970-3950
(516) 435-1110
(602) 244-5303
(805) 867-2555
(516) 435-1824
(602) 244-4015
(805) 867-2556
(708) 639-6400
(407) 241-7876
(708) 956-0666
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(800) 831-9172
(603) 224-1961
(207) 283-1941
(714) 960-6492
(814) 238-0490
(603) 224-1430
PHONE
FAX
_______________Detailed Description
Jumper Selection
The MAX747 has a TTL/CMOS-logic level input pin
(SHDN) to disable the output. Table 1 lists the options
for the shutdown control jumper, JU1. An external sig-
nal may be used by removing the JU1 shunt and con-
necting the control signal to the SHDN pad.
Table 1. Jumper JU1 Functions
SHUNT
LOCATION
1&2
2&3
SHDN PIN
Connected to GND
Connected to VIN
MAX747 OUTPUT
MAX747 Enabled,
V
OUT
= 5V
Shutdown Mode,
V
OUT
= 0V
Setting the Output Voltage
The MAX747’s output voltage can be set to 5V by
grounding FB, or it can be adjusted from 2V to 14V
using an external voltage divider. Resistors R4 and R5,
located on the solder side of the PC board, form a volt-
age divider between the output voltage and the FB pin.
Select a value between 10kΩ and 1MΩ for resistor R4.
Calculate R5 as follows:
V
OUT
R5 = (R4) ––––––– -1
2V
(
)
_________________________Quick Start
The MAX747 EV kit is fully assembled and tested.
Follow these steps to verify board operation.
Do not
turn on the power supply until all connections are
completed.
1) Connect a 6V to 15V power supply to the pad
marked VIN. Connect ground to the GND pad.
2) Connect a voltmeter and load (if any) to the VOUT
pad.
3) Place the shunt across pins 1 and 2 of JU1 for normal
operation.
4) Turn on the power supply and verify that the output
voltage is 5V.
Resistor R4 is shorted for a fixed 5V output. Be sure to
cut the shorting trace between the pads of R4 before
installing the resistor. Also, the shorting trace at JU2
must be cut to disconnect the OUT pin from the output.
In adjustable mode, the FB pin becomes the compen-
sation input pin (instead of the CC pin). Remove the CC
pin capacitor (C6) and install an FB pin compensation
capacitor (C9). Refer to the
Compensation Capacitor
section of the MAX747 data sheet for instructions on
selecting an appropriate capacitor value. The supplied
output capacitors are rated at 10V; use a higher rated
capacitor if necessary.
Using the Low-Battery Indicator
The MAX747 has an additional comparator that is useful
for monitoring the voltage level of the input source.
2
_______________________________________________________________________________________
MAX747 Evaluation Kit
Evaluates: MAX747
VIN
C2
68µF
20V
LBI
C7
68µF
20V
C3
0.1µF
3
SHDN
2
1
JU1
R2
OPEN
LBO
R3
OPEN
14
1
LBO
LBI
12
V+
4
SHDN
AV+
7
R6
0.068Ω
CS
9
R1
0Ω
C4
0.1µF
2
SS
MAX747
EXT
11
P1
L1
VOUT
C5
0.22µF
3
REF
D1
MBRS340T3
8
JU2
R5
OPEN
FB
5
33µH
C6
470pF
6
CC
OUT
10
AGND
C1
220µF
10V
C8
220µF
10V
13
GND
GND
C9
OPEN
R4
0Ω
Figure 1. MAX747 EV Kit Schematic
Resistor locations R1 and R2, on the solder side of the PC
board, are connected as a voltage divider between the
LBI pad and the MAX747 LBI pin. Note that a PC board
trace across R1 shorts the LBI pin to ground when this
function is not used. Cut the trace before installing R1.
Also note that the LBI pad is shorted to the VIN pad by
another PC board trace. Cut this trace if a voltage other
than VIN is to be monitored. Refer to the
Setting the Low-
Battery Detector Voltage
section of the MAX747 data
sheet for instructions on selecting values for resistors R1
and R2.
When using the LBO output, install a 100kΩ pull-up resis-
tor (R3). LBO is disabled in shutdown mode.
High Output Current Capability
The MAX747 can be configured to deliver higher output
currents. Take care to size external components according
to higher peak currents. Refer to the
Design Procedure
section of the MAX747 data sheet for further details.
Surface-mount inductors with higher current capability are
available from Coiltronics (CTX-03-12384) and CoilCraft
(DO3340).
_______________________________________________________________________________________
3
MAX747 Evaluation Kit
Evaluates: MAX747
Figure 2. MAX747 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX747 EV Kit Component Placement Guide—
Solder Side
Figure 4. MAX747 EV Kit PC Board Layout—Component Side
Figure 5. MAX747 EV Kit PC Board Layout—Solder Side
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.
4
___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1994 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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