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Product Key Points

BD70522GUL: DC/DC Converter Attaining Industry-Lowest 180 nA Current Consumption

Outstanding Functions Installed in an Ultra-Small Package

  • Constant On-time (COT) control
  • 100%-on mode
  • Automatic On-time extension function
  • VOUT discharge function
  • Power-good Output
  • Protection function
  • Small-size package and minimal external components
  • BD70522GUL-EVK-101 evaluation board

The BD70522GUL is a step-down DC/DC converter, with internal MOSFETs, that was developed for applications in mobile equipment, wearable equipment, IoT devices, and other battery-driven electronic equipment, and has achieved a current consumption of 180 nA, the world's lowest.*1 (*1: Result of a ROHM survey, as of January 23 2018)

Outstanding Functions and Protection in an Ultra-Small Package

The BD70522GUL provides top-notch functions in an extremely small package. For details, refer to the datasheet.

・Constant On-time (COT) Control

Through constant on-time control, operation is in continuous current mode (CCM) for moderate to high loading, with operation at substantially a constant frequency (1 MHz typ.) even when there is input/output fluctuation. Under light loading, operation is in discontinuous current mode (DCM), the switching frequency is changed according to the load, so that high efficiency is maintained even for light loads (refer to the previously presented frequency graph).

・100%-on Mode
The BD70522GUL is based on synchronous rectification by a high-side P-ch MOSFET and a low-side N-ch MOSFET. When the input voltage has approached the output voltage, operation with a 100% duty cycle by the high-side P-ch MOSFET is possible, and so the input voltage can be supplied to the output via the high-side MOSFET and an inductor. As a result, in applications that use battery input, the battery can be used to its maximum capacity.

・Automatic On-time Extension Function
In high duty cycles, the on-time is extended automatically, and by controlling internal operation, excellent transient response is offered.

・VOUT Discharge Function
A MOSFET for discharge is included at the VOUT pin; when in the standby state (output off), VOUT is lowered to GND level, to prevent malfunctions or the like in the device supplying power.

・Power-good Output
When the output voltage is at or above a preset voltage, this goes to H level, to provide power-good notification.

・Protection Functions
UVLO, overcurrent limiting, and thermal shutdown protection functions are provided.

・Small-size Package and Minimal External Components
A VCSP50L1C chip-size package measuring 1.76 mm × 1.56 mm × 0.57 mm is adopted, contributing to a small size with few external components.

The basic specifications are summarized below.

Part No. Input
Output Voltage Current
Operating Frequency Max.
BD70522GUL 2.5V

1.2V, 1.5V, 1.8V, 2.0V, 2.5V,
2.8V, 3.0V, 3.2V, 3.3V
180nA(Typ.) ±2.0% 0.2Hz~
500mA -40℃


Application Examples

The high efficiency and small size make this device suited to applications in wearable gear, mobile devices, battery-driven IoT devices (sensor nodes etc.), small-size industrial devices (alarm and reporting devices, electronic shelf labels, etc.). For similar reasons it is also well-suited to uses in energy harvesting equipment.

Support Information

The BD70522GUL itself as well as a BD70522GUL-EVK-101 evaluation board equipped with the BD70522GUL are being sold online. Please click here for purchasing information and other details.

BD70522GUL: DC/DC Converter Attaining Industry-Lowest 180 nA Current Consumption

Power Supply Design Technical Materials Free Download

Power Supply Design Technical Materials Free Download

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