R1282D002A Datasheet, PDF (18/18 Pages) RICOH electronics devices division – 2CH PWM DC/DC CONTROLLER

R1282D002A
TECHNICAL NOTES on EXTERNAL COMPONENTS
• External components should be set as close to this IC as possible. Especially, wiring of the capacitor
connected to VIN pin should be as short as possible.
• Enforce the ground wire. Large current caused by switching operation flows through GND pin. If the
impedance of ground wire is high, internal voltage level of this IC might fluctuate and operation could be
unstable.
• Recommended capacitance value of C3 is equal or more than 4.7µF.
• If the spike noise of VOUT1 is too large, the noise is feedback from VFB1 pin and operation might be unstable.
In that case, use the resistor ranging from 10kΩ to 50kΩ as R5 and try to reduce the noise level. In the case
of VOUT2, use the resistor as much as 10kΩ as R6.
• Select an inductor with low D.C. current, large permissible current, and uneasy to cause magnetic
saturation. If the inductance value is too small, ILX might be beyond the absolute maximum rating at the
maximum load.
• Select a Schottky diode with fast switching speed and large enough permissible current.
• Recommended capacitance value of C1 and C2 is as much as Ceramic 10µF. In case that the operation
with the system of DC/DC converter would be unstable, add a series resister less than 0.5Ω to each output
capacitor or use tantalum capacitors with appropriate ESR. If you choose too large ESR, ripple noise may
be forced to VFB1 and VFB2, and unstable operation may result. Use a capacitor with fully large voltage
tolerance of the capacitor.
• this IC, for the test efficiency, latch release function is included. By forcing (VIN−0.3)V or more voltage to
DTC1 pin or DTC2 pin, Latch release function works.
• Performance of the power controller with using this IC depends on external components. Each component,
layout should not be beyond each absolute maximum rating such as voltage, current, and power
dissipation.
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