DC Voltage Transformers - Installation -

DC/DC Transformers 12V / 24V
with adjustable, stabilized and filtrated output voltage

Reisemobil Offroad Blaulicht
Unit Type
Input Voltage/
max. Curent
Output Voltage
Output Constant
Current / Shot-time
Peak Current
DCDC 1212-20 3335 12V (10-16) / 24 12,0V, 12.5V, 13.0V, 13.8V 20A / 25A 250
DCDC 1224-25 3331 12V (9-16) / 50 25.0V, 26.0V, 27.0V, Vin/2 25A / 33A 1750
DCDC 2412-25 3332 24V (18-32) / 15 12.5V, 13.0V, 13.5V, =Vin/2 25A / 33A 1450
DCDC 1212-45 3337 12V (9-16) / 50 12.5V, 13.0V, 13.5V, =Vin 45A / 58A 1800
DCDC 2412-45 3339 24V (20-32) / 35 12.5V, 13.0,V 13.5V, =Vin/2 45A / 58A 1800
DCDC 1212 20 3335

Dimensions: (W x D x H): 146 x 67 x 40 mm
  DCDC 1212-25 3330
Dimensions: (W x D x H): 245 x 160 x 71 mm

DC/DC transformers allow the safe operation of consumers with voltage rates that are differing from the board voltage in the vehicle. For instance, many products of the information, entertainment or navigation technology are almost exclusively only available in 12V technology. Then, an operation with 24V board mains supply is possible by means of a suitable DC/DC transformer from 24V to 12V, without requiring to install an own 12V battery circuit.

However, also 12V/12V transformers become more and more important. VOTRONIC units are in a position to supply neatly stabilized and smoothed voltage for sensitive consumers, even though the operating voltage is disturbed significantly, or if it is subject to strong variations, such as it is the case for vehicles of newer generations with dynamically controlled dynamos. These characteristics ensure survival and neat operation of consumers, which had not been exclusively designed for automotive use, and which had been actually designed only for “12V” (out of own mains adaptors etc.).

The galvanic isolation between input and output of the units by separation of the ground paths effects an outstanding interference suppression (filtering). Even in case of long connection cables, perfect ground ratios being independent of each other are ensured on both sides, which is advisable for large vehicles, containers, roll containers, trailers etc.

Galvanisch isoliert ENBesides, the galvanic isolation (except DCDC 1212-20) also ensures absolute protection against 24 V / 12 V punctures, as well as overvoltage in case of loss of mass. Inrush current, peak current or starting current of the consumers are compensated by the short-time 30 % overload capacity of the transformers. One of three stable output voltages can be adjusted at the output, see table. The adjusted voltage is kept stable under most different conditions..

During the fourth operating mode, the output voltage directly follows the curve of the input voltage (Vin). If the system voltage rates at the input and output are differing, half (24V / 12V) or double (12V / 24V) of the value will be reproduced. During this operating mode, operation of such consumers is advantageous, which get further information from their operating voltage, such as starter battery is charged, driving or stationary mode, automatic disconnection in case of low voltage and battery discharge etc. (small consumers, charging trays, lamps). For protection of the consumers, the output voltage is limited in any case to maximum 15.0V (12V) or 30.0V (24V).

Activation of the transformers is effected by a control signal, either manually by means of the ON/Off-switch, or automatically by means of the vehicle’s ignition or signal D+ with activated generator. A further possibility is the automatic control by the operating voltage, which is advisable, if a further control signal is not at disposal. The function can be adjusted in 4 stages. A combined control by means of signal and voltage also covers special cases, such as the DC/DC transformer will only become active, if the starter battery had been charged to a certain minimum, if a battery discharge shall be avoided etc. 6 Pilot lamps always inform of the operating state and the load of the unit.

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