RP504x Series

Data Sheet / Flyer

The RP504x Series are low supply current CMOS-based 600mA* step-down DC/DC Converters with synchronous rectifier. Each of these ICs consists of an oscillator, a reference voltage unit, an error amplifier, a switching control circuit, a mode control circuit(Ver.A, D), a soft-start circuit, a "latch type" protection circuit, an under voltage lockout (UVLO) circuit, and switching transistors. A low ripple, high efficiency synchronous rectifier step-down DC/DC converter can be easily composed of this IC with only an inductor and capacitors. Since packages are SOT-23-5, DFN1616-6B, DFN(PLP)1216-6F, high density mounting on boards is possible.

As protection circuits, the RP504x Series contain a current limit circuit which limits the Lx peak current in each clock cycle, and a latch type protection circuit which latches the built-in driver to the OFF state if the load current exceeds the limit value or the output short continues for a specified time (the protection delay time). The latch protective circuit can be released by once putting the IC into the standby mode with the CE pin and then into the active mode, or, by turning the power off and back on. Setting the supply voltage lower than the UVLO detector threshold can also release the latch protective circuit.

In terms of the output voltage, since the feedback resistances are built-in, the voltage is fixed internally. 0.1V step output can be set by laser-trim and ±1.5% or ±18mV tolerance depending on the output voltage is guaranteed. By inputting a signal to a MODE pin, the RP504x Series can be switched between PWM/VFM auto switching control and Forced PWM control. PWM/VFM auto switching control switches to high-efficiency VFM mode in low output current. Forced PWM control switches to fixed-frequency Forced PWM mode for reducing noise in low output current.

• *) This is an approximate value, because output current depends on conditions and external parts.