RB125 126The RB Series is a pulse width-modulated DC to DC converter that provides regulated +28 VDC up to 5.0 amperes

The converter transforms an unregulated input from a 12V battery to a regulated +28 VDC output in a bootstrap mode.

The Model RB Series is primarily intended for use in an aircraft with 12 VDC battery system to operate 28 VDC equipment (especially during periods when the battery is not charged).


  • State of the art design for regulation and positive logic for output overvoltage protection.
  • Output is adjustable to 28 ± 2 VDC via an internal trim pot.
  • Designed to meet various applicable portions MIL-STD 704 notice 3, MIL-STD-202 and MIL-T-5422F class 1A.
  • The Model RB Series is serviceable, small and lightweight (110 watts per pound and 5.8 watts per cubic inch for the RB-126)
RB-125 RB-126
Input Voltage:
11-16 VDC 13.5-16 VDC
Input Current:
14-11 ADC 12-11 ADC
Output Voltage:
28 VDC 28 VDC
Output Current:
5.0 AMPS 6.0 AMPS
Efficiency @Full Load:
87% 90%
Output Ripple: 50 mVp-p plus input ripple.
Regulation: 2% for line, 2% load and 2% temperature. Refer to graph of input vs. output voltage.
Load Transient Response: 2V max. overshoot for 40 mSec typ. from FL to NL.
4V max. undershoot for10 mSec. typ.from NL to FL.
Protection (Overload): Output voltage collapses to input DC voltage when load exceeds approx. 6.5 to 7.5 amps.
Protection: Overvoltage circuit limits output to approx. 33 VDC.
Temperature: -55°C to +71°C (sufficient cooling required @ +71°C ambient); 25 SCFM of air or base plate temperature held @ 71°C
Altitude: 55,000 ft.
Size: 2.3" H x 2.3" W x 5.8" L.
5.7 cm H x 5.7 cm W x 14.6 cm L
Weight: 1.5 lbs. (683 grams).
Compliance: FAA TSO-C71


External Connections:

Pin Description Remarks
A +13.75 VDC Input Up to 16 VDC (See specs)
B Common Ground Input/Output Return
C +28 VDC Output Regulated, Factory set
D NC No Connection
E Connected to PIN A Parallel to input line


Model Receptacle Mating Connector
RB-125 MS3102A14S-5P MS3106A14S-5S
RB-126 MS3102A14S-5P MS3106A14S-5S


Outline Drawing | External WiringInput vs Output Voltage