Ricoh launches two Buck DC/DC Converters with 300 nA quiescent current and integrated battery voltage monitor

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Ricoh launches two Buck DC/DC Converters with 300 nA quiescent current and integrated battery voltage monitor

Osaka, Japan, June 6, 2019 - Ricoh Electronic Devices Co., Ltd. in Japan has launched two VFM mode Buck DC/DC Converters RP514 and RP515, designed for use in wearable devices and applications for the Internet of Things (IoT) requiring ultra-low current consumption to extend battery life. These products are equipped with a unique integrated battery voltage monitor to make it possible to measure the remaining charge left in the battery.

The additional battery monitor circuit is one of the key features of the RP514 and RP515, a conventional way to measure the remaining battery charge is using external divider resistors + MOSFET connected to an A/D Converter. However, the input impedance of an A/D Converter is generally low, therefore a considerable current flows to the ground, and drains the battery and reduces the lifetime of the application. The RP514 and RP515 provide a simple solution with a built-in resistor divider and voltage follower as a buffer. As an advantage, this circuit has a much lower current flow to the ground and the buffer output is compatible with the input impedance of the A/D converter.  In addition, all essential components are integrated into the chip, reducing valuable circuit board space and cost. In this way, it is possible for example to make a simple fuel gauge for primary batteries.

Today’s wearable and IoT devices mainly operate in a sleep mode, therefore power consumption is mainly defined by the quiescent current, which refers to a circuit’s quiet state, without any output 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 RP514 and RP515 have an impressive low quiescent current and consume only 300 nA, prolonging battery life or makes it possible for the designer to select a smaller sized battery for the application. The difference between the two products is their output current capability, they can provide respectively 100mA (RP514) and 300 mA (RP515). Both products offer synchronous rectification and have high and low side MOSFET driver transistors embedded.  The DC/DC Converters operate in a VFM mode which is best to achieve a high efficiency performance at low output current demands, the resulting peak efficiency is in the range of 95%.

“Under Voltage Lock Out” circuit is included, which is 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 with a constant slope, and prevents 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 RP514 and RP515 have an optional auto-discharge function; this feature rapidly discharges the output capacitor to the ground once the CE pin disables the chip. The solution with the WLCSP-9-P2 package occupies the smallest circuit board space whilst the budgetary version is available in a standard DFN (PLP) 2527-10 package.

Pricing and Availability
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Features RP514 / RP515    

DC/DC Converter  
Input Voltage Range 1.8 V to 5.5 V
Output Voltage Range (set internally in 0.1 V step) 1.0 V to 4.0 V
Output Voltage Accuracy (Vset ≥ 1.2 V) / (Vset < 1.2 V) ±1.5% / ±1.8%
Output Current 100 mA / 300 mA
Quiescent Current (device not switching) Typ. 300 nA
Standby Current 0.01 µA
PMOS On-Resistance (Vin = 3.6V, RP514K/RP515K / RP514Z/RP515Z) 0.19 Ω / 0.15 Ω
NMOS On-Resistance (Vin = 3.6V, RP514K/RP515K / RP514Z/RP515Z) 0.19 Ω / 0.15 Ω
Protection Circuits UVLO, Soft-Start, Lx Current Limit
Peak Efficiency (Vin = 2.0 V, Vout = 1.8 V) 95%
Operating Frequency Up to 1 MHz
Auto-Discharge Function With or without auto-discharge by product version
Battery Monitor  
Output Voltage 1/3 Vin or 1/4 Vin by product version
Supply Current 0.1 µA
Output Capacitor 0.1 µF to 0.22 µF
RP514K / RP515K Package: (L2.7 x W2.5 x H0.6 mm) DFN(PLP)2527-10
RP514Z / RP515Z Package: (L1.45 x W1.48 x H0.36 mm) WLCSP-9-P2


About Ricoh Electronic Devices Co., Ltd
Ricoh Electronic Devices Co., Ltd is a leading global provider of semiconductor products, offering a comprehensive portfolio of CMOS Power Management and Real Time Clock ICs that enable engineers to design advanced applications for the consumer, industrial and automotive markets. The company's headquarter is based in Japan, as well as development, sales and manufacturing facilities. Regional sales and support offices are located in North America, Europe, and Asia.

Ricoh has an extensive expertise in small package technology and has a focus on developing products providing features such as low-supply current, high-accuracy, high-efficiency and high-reliability. For further information, please visit