_______________general description the max831 evaluation kit (ev kit) provides a regulated 5.0v output voltage while operating on input voltages from 8.0v to 30v. it drives loads up to 1a with conver- sion efficiency greater than 80%. the max831 ev kit is a fully assembled and tested sur- face-mount printed circuit board. this kit comes with a 5v-output max831 ic, but it can also be used to evalu- ate the max833 (3.0v output), max832 (3.3v output), or max830 (adjustable output). additional pads are provided on the board's solder side to accommodate the external feedback resistors used with the max830. ____________________component list ____________________________features ? 8v to 30v input voltage range ? 5v output voltage ? up to 1a continuous output current ? 140? shutdown supply current ? 8ma quiescent current ? internal power switch ? adjustable current limit ? surface-mount construction ? fully assembled and tested evaluates: max830?ax833 max831 evaluation kit 1 maxim integrated products _______________________________________________________________ call toll free 1-800-998-8800 for free samples or literature. desig- nation qty description c1, c2 2 33?, 35v, low-esr tantalum capacitor sprague 595d336x0035r2b c3, c4 2 220?, 10v, low-esr tantalum capacitor sprague 595d227x0010r2b or avx tpse227m010r0100 c5 1 0.047? ceramic capacitor r1, r2, r3 0 open r4 1 10k , 5% resistor d1 1 3a, 40v 1n5822 (smt) schottky diode nihon nsq03a04 motorola mbrs340t3 l1 1 100?, 1.3a inductor coilcraft d03316-104 u1 1 maxim max831cwe j1 1 2-pin header none 1 shunt none 1 max831 pc board none 1 max831 data sheet ______________component suppliers (805) 867-2556 (805) 867-2555 nihon (207) 283-1941 (207) 282-5111 avx (814) 238-0480 (814) 237-1431 murata-erie (602) 244-4015 (602) 244-3576 motorola (704) 264-1972 (704) 264-8861 irc (603) 224-1430 (603) 224-1961 sprague (708) 639-1469 (708) 639-6400 coilcraft fax phone supplier surface mount 0? to +70? max831evkit-so pin-package temp. range part ______________ordering information
evaluates: max830?ax833 max831 evaluation kit _______________________________________________________________________________________ 2 ___________________quick reference the max831 ev kit is a fully assembled and tested sur- face-mount board. follow the steps below to verify board operation. do not turn on the power supply until all connections are completed. 1) connect an 8v to 30v supply to the pad marked vin. the ground connects to the gnd pad. 2) connect a voltmeter and load (if any) to the vout pad. 3) remove the shunt on j1 for normal operation. 4) turn on the power and verify that the output voltage is 5.0v. instructions for modifying the board for different output voltages appear in the sections evaluating the max832 and max833 and other output voltages . _______________detailed description jumper selection the two-pin header j1 selects the shutdown mode. table 1 lists the jumper selectable options. table 1. jumper j1 functions notes about inductor selection the 100? coilcraft d03316-104 inductor that comes mounted with the ev kit has low resistance and a medi- um current rating (1.3a). it provides excellent perfor- mance over the line and load ranges of the max830/max831/max832/max833. for additional information on inductor selection, refer to the max830?ax833 data sheet. evaluating the max832 and max833 the max831 can be replaced by a max833 to gener- ate a 3.0v output voltage with output current up to 1a, or by a max832 to generate a 3.3v output voltage with output current up to 1a. the only modification required is to replace the ic. shunt location s h d n pin max831 output off floating max831 enabled, v out = 5.0v on connected to gnd shutdown mode, v out = 0v max831 v out
+5v c4
220?
10v c3
220?
10v c5
0.047? d1
1n5822 r4
10k shdn gnd l1
100? v sw v sw v sw v sw gnd v c gnd shut v in v in v in v in gnd i lim gnd sense c1
33?
35v c2
33?
35v r3
open r2
open r1
0 w v in
+8v to +30v 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 u1 j1 figure 1. max831 ev kit schematic diagram
evaluates: max830?ax833 max831 evaluation kit 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. 3 ___________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 (408) 737-7600 1995 maxim integrated products printed usa is a registered trademark of maxim integrated products. other output voltages the max831 can be replaced with a max830 to gener- ate output voltages in the 2.5v to 25v range using external resistors. besides replacing the ic, the only other modifications required are to cut the trace short- ing resistor r1, add the output-voltage-divider resistors r1 and r2 (located on the board's solder side), and use low-esr output capacitors with the proper volt- age rating . the pin description section of the max830?ax833 data sheet gives instructions for cal- culating the values of external feedback resistors r1 and r2. reducing current limit to reduce the output current to below 1a, or to reduce the peak current limit to below 1.3a, install the current- limiting resistor, r3, onto the board's solder side. see note 7 in the max830?ax833 data sheet for instruc- tions on selecting the resistor value. board diagram drawn to reduced scale. board diagram drawn to reduced scale. board diagram drawn to reduced scale. figure 2. max831 ev kit component placement guide component side figure 3. max831 ev kit component placement guide solder side figure 4. pc board layout?omponent side figure 5. pc board layout?older side board diagram drawn to reduced scale.
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