New Industry Products

RECOM Adds to its RPX Series of Tiny Buck Converters

June 29, 2021 by Gary Elinoff

The new device works from a 3.8- to 36-volt input and provides a programmable 4-amp output ranging from 1 to 7 volts

The RPX-40 features a 5 x 5.5 mm package only 4.1 mm high, encased in a thermally-enhanced QFN package.

The RPX-40 series. Image courtesy of RECOM

The RPX-4.0 buck regulator module features on-off control, a power good signal and offers protection against over-temperature (OTP), over-current (OCP), under-voltage (UVLO) and short circuit (SCP). The converter also features an internal soft-start time of 5ms. 

The highly efficient unit operates at temperatures of up to 90℃, with power derating beginning at 65°C, and it employs flip-chip on leadframe construction for enhanced thermal behavior.


A Highly Integrated Solution

The RPX-4.0 only needs a few external components to affect a complete power solution. These include input and output capacitors, and two resistors to set the output voltage. The unit includes an integrated shielded inductor for low EMI, and the switching frequency (typical value of 1.4 MHz) is automatically controlled to enable high efficiency even when the unit operates at light loads. 

As per Matthew Dauterive DC/DC product manager of RECOM, “We are excited to launch the latest in our RPX series of buck converters.” He goes on to state that, “Users will find it particularly suitable for industrial automation, test and measurement, portable devices, and high density or weight-sensitive applications”.


Operating Conditions

The converter’s typical standby current is 5µA. Load and line regulation are ±0.40% and 0.15%, respectively. Output ripple and noise, over a 20MHz bandwidth, is 30mV peak-to-peak.


Setting the Output Voltage

Setting the output voltage is achieved through the choice of two resistors. Both are connected to the FB (feedback) pin, one to the voltage output pin and the other connected to ground. The details are set forth in the datasheet.


The Control Pin

The control pin controls the On/Off status of the buck converter

  • ON: VCTRL > 1.26 VDC
  • Standby: 0.3 VDC ≤ VCTRL ≤ 1 VDC
  • OFF: VCTRL <0.3VDC



  • Test and measurement
  • Automation
  • Portable devices
  • Use cases where high density and/or light weight is critical



The unit has a typical weight of 2.0 grams


Regulatory and Safety Considerations

  • Mechanical
    • Mechanical shock, as per MIL-STD-883D, Method 2002.3, 1 msec, 1/2 sine, mounted is 500G
    • Mechanical Vibration. As per MIL-STD-883D, Method 2007.2, 20 to 2000 Hz is 20G
  • Electrostatic Discharge
    • Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 is ±2.5kVDC
    • Charged-device model (CDM), per JEDEC specification JESD22-C101 is ±1.0kVDC


Getting to Market Faster

Soon to be available, the RPX-4.0-EVM is an evaluation platform for the RPX-4.0 buck regulator module. The unit makes it easy for designers to evaluate output voltage selection as well as the control, and sensing functions. Critical thermal design considerations can also be explored.

The RPX-4.0-EVM evaluation module for the RPX-4.0. Image courtesy of RECOM
The RPX-4.0-EVM evaluation module for the RPX-4.0. Image courtesy of RECOM

The evaluation module makes it possible to observe critical overload and over-temperature behavior before the module is designed into an OEM product. It also empowers designers to optimize filtering based on the needs of specific system requirements.