R1232D Datasheet, PDF (9/24 Pages) RICOH electronics devices division – PWM STEP-DOWN DC/DC CONVERTER WITH SYNCHRONOUS RECTIFIER

R1232D
When you use these ICs, consider the following issues;
• Input the same voltage into power supply pins, VIN and VDD. Set the same level as AGND and PGND.
• When you control the CE pin by another power supply, do not make its "H" level more than the voltage level
of VIN / VDD pin.
• Set external components such as an inductor, CIN, COUT as close as possible to the IC, in particular,
minimize the wiring to VIN pin and PGND pin.
• At stand by mode, (CE="L"), the LX output is Hi-Z, or both P-channel transistor and N-channel transistor of
LX pin turn off.
• In terms of the protection circuits, current limit for the peak current of each cycle of Lx, and the latch
protection circuit, which works if the over-limit current flows continuously for a certain time exist. To release
the protection, once make this IC into be standby mode with chip enable pin, or make the supply voltage be
down to UVLO threshold level or less.
• Reinforce the VIN, PGND, and VOUT lines sufficiently. Large switching current may flow in these lines. If the
impedance of VIN and PGND lines is too large, the internal voltage level in this IC may shift caused by the
switching current, and the operation might be unstable.
• Connect the TEST Pin to the "L" or GND level.
The performance of power source circuits using these ICs extremely depends upon the peripheral circuits.
Pay attention in the selection of the peripheral circuits. In particular, design the peripheral circuits in a way that
the values such as voltage, current, and power of each component, PCB patterns and the IC do not exceed their
respected rated values.
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