400mA Synchronous Step-Down DC/DC Module with MODE Pin and Inductor

400mA Synchronous Step-Down DC/DC Module with MODE Pin and Inductor

RICOH introduced RM590 with a powerful 400mA Buck DC/DC converter and built-in inductor along with the high operating frequency of 6 MHz which, requires a significantly small PCB board space and a low number of external components. The RM590 can be configured for either PWM/VFM automatic shift operation or forced PWM operation by controlling of MODE pin. Targeted applications for the RM590 are products with a high degree of miniaturization such as wearables and portable gadgets as well as other consumers, industrial and IoT devices.

Optional features are selected by the product version, it has an auto-discharge function that rapidly discharges the output capacitor once the CE pin turns off the chip and one can select between a fixed or adjustable output voltage version. The RM590 is available in a QFN2220-8 package with dimensions of 2.2 x 2.0 x 1.5 mm.


  • By having an inductor built-in, it is possible to simplify the board design and reduce the mounting area
  • PWM/VFM automatic shift operation provides high efficiency at light loads
  • By having an inductor built-in, the number of parts can be reduced, and the man-hours for managing purchased parts can be reduced (concern about EOL)


  • Input voltage range (maximum rating)
    • 2.3V to 5.5V (6.5V)
  • Output voltage (fixed output voltages)
    • from 0.6V to 3.3V in 0.1V increments
    • ±1.5% (VSET ≥ 1.2V), ±18mV (VSET < 1.2V)
    • Output voltage accuracy
  • Output voltage (adjustable output voltages)
    • 0.6V to 5.5V
    • 0.6V reference (VFB), ±9mV voltage accuracy
  • Selectable oscillator frequency (typ. 6.0MHz)
  • Oscillator maximum duty (min. 100%)
  • MOSFET ON resistance (VIN = 3.6V)
    • High side MOSFET typ. 0.245Ω
    • Low side MOSFET typ. 0.225Ω
  • Typ. 2.0V UVLO detector threshold
  • Typ. 0.15ms soft-start time
  • Thermal shutdown function
    • Detection temperature 140°C
    • Release temperature 100°C

more information: https://www.n-redc.co.jp/en/products/dc-dc-switching-regulator/spec/?product=rm590

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Mike is the founder and editor of Electronics-Lab.com, an electronics engineering community/news and project sharing platform. He studied Electronics and Physics and enjoys everything that has moving electrons and fun. His interests lying on solar cells, microcontrollers and switchmode power supplies. Feel free to reach him for feedback, random tips or just to say hello :-)

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