DCP02 SERIES ISOLATED/UNREGULATED DC/DC CONVERTERS

The DCP02XXXX   are  low current unregulated ,DCP020515DP and the DCP021212DP. very low current  2W converters. The average maximum current for  each polarity is about 1W/ 12V wide ranging Vout  or 83mA  per polarity or 1W/15V 66mA per polarity. the  voltage  can range between 11.5V to 25V unloaded per polarity These low current converter   application exceeds the maximum  1A to 2A current as required .

Thanks Tom! I forgot to mention that I want to use the DCP02’s to power some op-amps used a voltage followers to boost the input impedance to a DATAQ D-194. I would also like for this power supply to be able to run several things at once. I am using a 24V center-tapped transformer rated at 2 amps and that works out to 48 watts. I have been studying the data sheets on the DCP02’s, UA78xx’s, LM317’s, and LM337’s. They talk about the advantages of using designs that incorporate voltage regulation at the load instead of central regulators having bus-bars.

I have decided on using an LM317 in a shunt configuration able to handle several amps using power transistors as series pass elements. (Fig. 14, page 12 of the LM317 datasheet.) and setting it for 24 volts (V_P is 34V). From there I will use DCP02’s for dual polarity to power op-amps and UA78xx’s, LM317/337’s to power whatever else I put on it.

I would like to know if TI has a dual polarity IC able to handle more than 2 watts.

The   in-rush current is totally dependent upon the dv/dt of the power source.The DCP series regardless of  input or output  voltages can have in-rush current of up to 750mA. The Input  power source can be foreced into current limit during power-up duration. The power source , when in current limit,which is the DCP   longer on duration until it is at  normal operating voltage. This delay  may eventually overstress the  DCP and possible thermal damaged can occur.

One recommendation to eliminate the  in-rush current is to:

It may require  adding  a soft start control circuit delaying   the start-up of the DCp021515 for 7 msec or until the  15V bus is actively high.This delay will prevent the activation of the 15V bus current limit  . Additional input capacitance 100uf  may be required to hold-up the  15V bus during the DCP021515Uactive switching transition .This circuit  can be added to the input sync. pin,.

I added in an attachment for delaying the start-up of the input voltage 15V, 12V  DCP series converters.  

Tom

Arash;

The use of a 33uF or 47uf ceramic can affect the operation of the DCP series products.  I recommend no more than 10uF low ESR ceramic capacitance on each bus.

Tom