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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 0C to +70C BOARD TYPE Surface Mount
____________________Component List
DESIGNATION C3, C4 C5 C6 QTY 2 1 1 DESCRIPTION 0.1F ceramic capacitors 0.22F ceramic capacitor 470pF ceramic capacitor 220F, 10V, low-ESR tantalum capacitors AVX TPSE227M010R0100 or Sprague 595D227X0010R2T 68F, 20V, low-ESR tantalum capacitors AVX TPSE686M020R0150 or Sprague 595D686X0020R2T 3A, 20V Schottky diode (SMT) Nihon NSQ03A02, Motorola MBRS340T3 or IR30BQ040 33H, 1.8A inductor (SMT) Sumida CDR125-330, CoilCraft D03316-333 P-channel MOSFET (SO-8) Motorola MMSF3P02HD, Siliconix Si9430DY or IRF7204 0.068, 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 (602) 244-3576 (408) 988-8000 (310) 322-3332 (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 (708) 639-1469 (407) 241-9339 (708) 956-0702 (207) 282-5111 (800) 282-4975 (714) 969-2491 (814) 237-1431 (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 signal may be used by removing the JU1 shunt and connecting 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, VOUT = 5V Shutdown Mode, VOUT = 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 voltage divider between the output voltage and the FB pin. Select a value between 10k and 1M for resistor R4. Calculate R5 as follows: VOUT 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 compensation 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 68F 20V LBI
C7 68F 20V
C3 0.1F 3 SHDN 2 1 JU1
R2 OPEN LBO
R3 OPEN 14 1 LBO LBI
12 V+
4 SHDN AV+ 7 R6 0.068 CS 9
R1 0 C4 0.1F 2 SS
MAX747
EXT
11
P1 L1 VOUT
C5
0.22F
3
REF
D1 MBRS340T3 8 JU2 R5 OPEN FB 5
33H
C6
470pF
6
CC
OUT
10
AGND
C1 220F 10V
C8 220F 10V
13 GND
GND
C9 OPEN
R4 0
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 LowBattery 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 100k pull-up resistor (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 (c) 1994 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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