Ricoh launches two VFM mode Buck DC/DC Converters with Ultra-low Output Voltage for wearables and IoT devices

Jun 5, 2019

Campbell, CA, June 5, 2019 – Ricoh Electronic Devices Co., Ltd. in Japan has launched two Buck DC/DC Converters RP516 and RP517, designed for use in wearable devices and applications for Internet of Things requiring advanced solutions extending battery life, reducing mounting area and weight on high density boards.

Today’s wearable and IoT devices mainly operate in a sleep mode and therefore power consumption is significantly defined by the quiescent current, referring to a circuit’s quiet state, not driving any load. In this mode, the system is idle but ready to wake up at any time to perform a task, transmitting some data and resume to sleep mode again.

The RP516 and RP517 are optimized to prolong battery life and are designed for applications that require a low supply voltage in between 0.3 and 1.2 V. The DC/DC Converters operate in a VFM mode and the efficiency at light load 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 impressive low quiescent current of only 300 nA also contributes to extend battery life or makes it possible for the designer to select a small 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 8.3 mm2 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 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, DFN2527-10, SOT89-5


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Headquartered in Tokyo, Ricoh Group operates in approximately 200 countries and regions. In the financial year ended March 2019, Ricoh Group had worldwide sales of 2,013 billion yen (approx. 18.1 billion USD).

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