New Industry Products

Powerbox Debuts 1200 W Power Supply with Adjustable “Near-to-zero” Output Voltage and Current

March 30, 2022 by Gary Elinoff

The new device is optimized for conduction cooling, operating across a baseplate temperature range of -40 to +95 °C without the use of a fan.

Powerbox’s new OFI1200A operates over an input voltage range of 85 to 305 VAC. It is available in three versions, each with a single output of either 12 V at 84 A, 28 V at 43 A, or 48 V at 25 A.


The OFI1200A. Image used courtesy of Powerbox 

With a 230 VAC input, the 48-volt unit achieves an efficiency of 92%. The power supply also sports a power factor of 0.98 and 0.95 at input voltages of 110 and 230 VAC, respectively.


Conduction Cooling

In certain environments, designers may conclude that power supplies must be cooled without the typical combination of a fan and ventilation. In harsh industrial settings or in tough outdoor weather conditions, it may be necessary to seal supplies entirely to protect their sensitive electronic components against all hazards. In especially remote or even dangerous locations, a fan’s susceptibility to failure may present prohibitive maintenance requirements.

Still in other cases, the audible noise the fan produces may be unacceptable. 

Those concerns in mind, Powerbox has built its OFI1200A power supply in accordance with the very specific building practices necessary to enable conduction cooling. Components within the supply are situated so as to guarantee that the heat they generate is effectively and efficiently transferred to the baseplate, and from there safely diffused to the chassis. 


Adjusting Current and Voltage

Two analog inputs enable users to adjust the OFI1200A’s output voltage and current from near zero to the device’s maximum. Alternatively, users can adjust output voltage using the provided onboard potentiometer. See below for specifications: 

OFI1200A Model Specs
Model Number Output Voltage Output Current Ouput Voltage adj. Efficiency
110 VAC/230 VAC
OFI1200A12 12 VDC ~0-84 A  ~0-14.4 VDC  84.8% / 86.5% 
OFI1200A28 28 VDC ~0-43 A  ~0-33.6 VDC 88% / 90.5% 
OFI1200A48 48 VDC ~0-25 A  ~0-57.6 VDC  89% / 92% 


The unit can also operate in either constant current or constant voltage mode. In addition, whether for boosted redundancy or increased power, up to nine of the new power supplies can be connected in parallel. 


Safety and Isolation

All three versions of the OFI1200A have IN/OUT isolation of 3,000 VAC. Input-to-ground and output-to-ground isolations are 2,000 and 500 VAC, respectively.

The power supplies comply to:

  • UL62368-1 3rd edition 2019
  • CSA 22.2 No 62368-1:19 3rd edition

The units also feature overcurrent protection with auto-recovery, as well as protection against overvoltage and overtemperature. 



  • Harmonic attenuator: EN61000-3-2 class A
  • Flicker: EN61000-3-3
  • Conducted noise: EN55032 class B (valid with or without optional cover)
  • Radiated noise: EN55032 class A (valid with or without optional cover)
  • EMS immunity: Compliance to EN61000-4-2, 3, 4, 5, 6, 8, 11


Shock and Vibration

The OFI1200A has passed shock and vibration testing as specified in MIL-STD-810H. The units are designed to stand up to 20G level, far in excess of anything likely to be encountered under normal operating conditions.


Physical Considerations

The OFI1200A measures 142 x 39 x 260 mm (5.59 x 1.54 x 10.36 inches) in its open frame format, and it weighs only 1.2 kg, maximum.


Open and closed-frame schematics of the OFI1200 A. Image used courtesy of Powerbox 

The unit's optional metal cover adds 1 mm to the its height and 200 grams to its weight. 


Environmental Notes 

The power supplies are RoHS-compliant


Feature image used courtesy of Powerbox