Ricoh adds buck dc/dc converters for wearables, IoT

The chips are designed for applications that require a low supply voltage in between 0.3 and 1.2 V. This kind of power supply is tailored to support the newest generation of low power MCU’s, GPS/GNSS receiver/processors and other ICs which are required in IoT applications for a low power wireless sensor network and wearable devices.

The DC/DC Converters operate in a VFM mode and the efficiency at light loads in particular was considerably improved and has a peak at 75%, even at 0.01 mA output current an efficiency performance of about 67% is achieved (conditions: Vout=0.5V, Vin=1.8V).

The quiescent current of 300nA contributes to extend battery life or makes it possible for the designer to select a smaller sized battery for the application.

The main difference between the two products is their output current power; they deliver 100 and 300 mA respectively.

Both products offer synchronous rectification and have high and low side MOSFET driver transistors embedded.

Three different packages are available: A standard SOT-89-5, leadless DFN2527-10 or the most compact WLCSP-8-P1 package.

By using the proposed external components, it takes up only 8.3mm2 of printed circuit board area.

Thanks to the wide input voltage range, the two DC/DC Converters are able to operate from various power supplies like a USB port, a single cell Li-Ion and other regular batteries.

Protection circuits are integrated: An Under Voltage Lock-Out circuit disabling the DC/DC Converter in case the input voltage drops below a minimum threshold.

A soft-start circuit controls the output voltage to ramp-up smoothly, preventing any output overshoot and undershoot during the start-up period.

The Lx current limit circuit prevents the peak current through the inductor to exceed a specific maximum current threshold.

The RP516 and RP517 have an optional auto-discharge function; this feature rapidly discharges the output capacitor once the CE pin disables the chip.

Features of RP516 / RP517

Input Voltage Range

Output Voltage Range

Output Voltage Accuracy

Output Current

Quiescent Current

Standby Current

PMOS On-Resistance

NMOS On-Resistance

Protection Circuits

Peak Efficiency

Operating Mode / Frequency

Auto-Discharge Function


1.8 V to 5.5 V

(in 0.1 V step) 0.3 V to 1.2 V

±18 mV

100 mA / 300 mA

(device not switching) Typ. 300 nA

0.01 µA

(Vin = 3.6V, RP516Z / RP517Z) 0.15 Ω

(Vin = 3.6V, RP516Z / RP517Z) 0.15 Ω

UVLO, Soft-Start, Lx Current Limit

(Vin = 1.8 V, Vout = 0.5 V) 75%

VFM / Up to 1 MHz


WLCSP-8-P1, DFN252710, SOT89-5



The datasheet can be read online.