DCP021212D: Outputs higher voltage than spec.

Jongkap Oh

Intellectual 320 points

Part Number: DCP021212D

Hello,

In order to get isolated 24V power supply, I designed and implemented a circuit with DCP021212DU as below.

By the way, the measured values of VCC24V_ISO is about 28V and COM to +VOUT/-VOUT are 14V.

Please give me an advice to get correct output voltage.

For your reference, DNP means "do not place".

The purpose of U25 and few parts of around it is to increase current capability in case.

Thanks.

over 6 years ago

0 David Baba over 6 years ago

TI__Mastermind 36460 points

Hello Jongkap,

This device is unregulated and as such the output will depend on the load current. Please refer to the datasheet Page 3 which details the load regulation variation as a function of load.

hope this helps?

0 Jongkap Oh over 6 years ago in reply to David Baba

Intellectual 320 points

Hello David,

Thank you for your comment.

I tested and confirmed that the output voltage depends on load current.

1. Does it mean the DCP02 should not be used stand alone?
I have a plan that I will use TPS7A4901 which is adjusted for 22V after DCP02 to get constant output voltage.
How about this? Would you let me know your opinion about this?

2. Would you let me know VOUT values of DCP021212DUat 10%, 100% and 75% load current?

3. When the DCP021212DU circuit is configured to output 24V, What is the maximum output current value? 83 or 166 mA ?

Thanks.

0 David Baba over 6 years ago in reply to Jongkap Oh

TI__Mastermind 36460 points

Hello Jongkap,

1. If you need a regulated output with no variation with load current, adding an LDO is the typical approach, so yes, your approach is very feasible.

2. The load regulation is given in the table as a percentage you can back calculate this using footnote 2 at the bottom of the table.

3. Output current is 83mA because footnote 3 states Iout 1 + Iout 2.

Hope this helps?

0 Jongkap Oh over 6 years ago in reply to David Baba

Intellectual 320 points

Hello David,

I need specific number of VOUT voltages of DCP021212DU at 10%, 100% and 75% load, or I need a graph shows Output Voltage vs. Output Current such as figure 3.
Not only for load regulation, but I will consider the numbers to design LDO input / output voltage and power dissipation.
Just with 7 ~ 20% of load regulation, back calculation makes various combinations of the numbers.
I hope you can help me out.

Thank you.

0 J Arrigo over 6 years ago in reply to Jongkap Oh

TI__Mastermind 28020 points

Hi Jongkap,

The above graph shows typical Vout Load Reg from 10% to 100% load at room temp. This data shows the DCP021212D configured for 24V output by measuring across +Vout to -Vout.

Thanks, Jason