RP902 Series are CMOS-based compound power supply IC with Voltage Detector (VD), Voltage Detector (VD), PWM/VFM Auto-switching Step-down DC/DC Converter with synchronous rectifier (DD1), PWM Step-down DC/DC Converter control type with synchronous rectifier (DD2) and PWM Step-up DC/DC Converter control type (DD3).

PWM/VFM Auto-switching Step-down DC/DC Converter control type with synchronous rectifier (DD1) has the adoption of the synchronous rectification method that the switching element is built- in. A highly effective step-up DC/DC converter can be composed only of the coil and the capacitor as external parts. The PWM/VFM auto-switching control method is for achieving highly effective at VFM mode.

PWM Step-down DC/DC Converter with synchronous rectifier (DD2) has the adoption of the synchronous rectification method that the switching element is built- in. A highly effective step-up DC/DC converter can be composed only of the coil and the capacitor as external parts.

PWM Step-up DC/DC Converter (DD3) has the asynchronous rectification method by NMOS switching element built-in. The step-up DC/DC converter can be composed only of the diode, the coli, the capacitors and resistances as external parts.

When a large output current is necessary, to control by the additional external NMOS is possible. When the output voltage is necessary to cut when it is off, to control additional external PMOS is possible.

As the protection circuits, the current limit circuits of DD1 and DD2 for limiting peak current of Lx at each clock cycle, and DD3 has the ratio limitation time function. This IC has also the built-in reset type protection function.

When the limited condition is continue in certain time, the reset-start function is operated. The built-in low voltage detection circuit (UVLO) is operating for stopping the output to prevent the malfunction when a low voltage is detected.

As the soft-start circuits, the time of DD1, DD2 and DD3 is fixed. And DD1 and DD2 have the start-up order control function by the trimming.

DD1 and DD2 have the built-in feed-back resistance. The setting output voltage is fixed. It can set by the trimming in 0.1V step. DD3 has the feed-back resistance in externally. The setting output voltage can set between 5.0V and 11V.

Controlling the external pin, it is possible to changing the output voltage dramatically from 72.7% to 100%.
(The output voltage range is between 11V and 8.0V (72.7%) when the default output voltage is set to 11V by the external feed-back)
To using the trimming options, it is also possible to changing the output voltage dramatically from 57.8% to 100%.
(The output voltage range is between 9V and 5.2V (57.8%) when the default output voltage is set to 9V by the external feed-back)
The Voltage Detector is monitoring the input voltage; the output is Nch open drain output. Power-on reset delay time is also included and it is possible to selected 50ms or 100ms by the trimming.