KIS-3R33S 데이터 시트보기 (PDF) - Unspecified
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KIS-3R33S Datasheet PDF : 8 Pages
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Necessary modification of the module consisted in removal and replacement of three SMD resistors, done
as follows.
The module is very small, measuring 21x22x10 mm total. To modify it one must remove the bottom cover
and then remove module from its housing, not difficult, the cover is snap-on type.
Resistors R3, R4 (both marked 513 i.e. 51 k Ohm) and R6 (marked 332 i.e. 3.3 k Ohm) should be removed,
and replaced. R3 and R4 with 39 k Ohm and 180 k Ohm (order of placement is unimportant as they are
connected in parallel). Resistor R6 should be replaced with one of the 51 k Ohm resistors removed from R3
or R4 positions.
The additional components are the logarithmic tracking potentiometer VR1 220 k Ohm (470 k Ohm if 3W
LED is used to bring up output voltage to 3.7 V), connected externally, and optionally a switch can be
connected from ground GND (marked on circuit diagram and component layout) to terminal EN which
when switch is engaged turns off the DC-DC converter. The two ceramic capacitors, 10uF /25V, one should
be connected across VIN and GND and another across VOUT and GND.
The value of the resistor R6, chosen to prevent voltage output falling below 2.70 Volts as below that value
LED will cut off. Combination of resistors R3, R4, R5, R6 and VR1 determines the output voltage
according to the following formula:
Vout = (((R3||R4||(R6+VR1))+R5)/R5)*0.925
Resistors R3, R4, R6+VR1 (R6 is connected in serries with VR1) are connected in parallel and are actually
acting as one resistor. To calculate value of two or more resistors in parallel:
Rx=1/(1/R1+1/R2+1/Rn)
in our case Rx=1/(1/R3+1/R4+1/(R6+VR1))) so Vout becomes:
Vout = (Rx+R5)/R5)*0.925 (where R5 stays unchanged, as is, 10 k Ohm)
LED is mounted onto simple carrier made from 1 mm thick aluminum sheet, which also serves as heat
sink, it easily mounts inside the body of the OI-32 (no modifications to the OI-32 housing were needed).
Carrier is so constructed to place LED at the exact place where the incandescent lamp filament was. I
mounted power module unit on a small piece of proto-board and fixed it onto the bottom side of the carrier,
under the LED.
In order to close the opening where the incandescent lamp was located originally, I have machined a “plug”
out of Delrin (Polyoxymethylene) and mounted the potentiometer inside it.
To improve overall performance of the illuminator and to achieve even more flat and uniform illumination,
it was suggested to place a ground glass filter just above the LED.
Note: If LED flicker is experienced, then the ‘Soft Start’ capacitor C3, part of the module, should be
removed.
Parts required:
KIS-3R33S module
Power LED
Resistor SMD 603
Resistor SMD 603
Potentiometer
or
C* Capacitor X5R SMD 1206
Switch SPST
Proto board
1W or 3W
39k
180k
220k log
470k log
10uF/25V
1 pc.
1 pc.
1 pc.
1 pc.
1 pc.
1 pc.
2 pcs.
1 pc.
– use with one-watt LED
– use with three-watt LED
– optional
References:
1. HPB8-49KxWHBx data sheet - HUEY JANN ELECTRONICS INDUSTRY CO., LTD.
2. HPB8b-49K3xWHBx data sheet - HUEY JANN ELECTRONICS INDUSTRY CO., LTD.
3. MP2307_r1.9 data sheet - Monolithic Power Systems, Inc.
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