Post Go back to editing

Category: Hardware

Hello,

I'm planning to use the ADP1031 for realizing an isolated analog output. However I have difficulties to reach the needed output current IVOUT1(MAX) of 30mA

I want to use following values:

VINP=6V or 24V

VOUT1=15V

VOUT2=5V

VOUT3=-15V

LPRI=280µH

Using above values and interim results from other formulas in the datasheet, I calculate following values with the formula on page 32:

IVOUT1(MAX)=14,1mA for VINP=6V and 20,1mA for VINP=24V

Both are considerably below the needed 30mA. Can you help me to increase IVOUT1(MAX) or is the part not suited for such a output current?

## Top Replies

Parents
• The interim results:

VD=0,5V

DCCM=0,72 for VINP=6V and DCCM=0,39 for VINP=24V

IAC=61,7mA for VINP=6V and IAC=133,7mA for VINP=24V

IPEAK=138mA for VINP=6V and IPEAK=116mA for VINP=24V

• Hi MrkBldn,

For the given conditions:

VINP=6V or 24V, VOUT1=15V, VOUT2=5V, VOUT3=-15V

LPRI=280µH (I assume this is the default transformer 750316743).

Yes, you can compute for the maximum output power using the equation on page 32 to get the approximate max output value but the actual results may vary due to the tolerances and the efficiency number for the given condition.

You can look at figure 23 to the typical maximum output current for various output and VINP levels. Take note the this max IOUT value is for VOUT1 and NO load in VOUT2 and VOUT3. Also take that this is measure at the 70% of the current limit threshold to account for different variability like the tolerances and part to part variation.

Based from figure 23, you can get a bit more than 40mA on VOUT1 with 6V VINP and about 90mA IOUT1 with VINP of 24V.

Thanks and regards,

Jefferson

• Hi Jefferson,

thanks for the answer. Yes the default transformer 750316743 should be used. So it is save to take the values from figure 23 and ignore the results from the equation on page 32?

Best regards

Mark

• Hi Mark,

Yes, you can take max IOUT1 values  from figure 23 since you will be using the same transformer. May i know what will be your load on VOUT2 and VOUT3? The Buck and the Inverting buck-boost are powered from VOUT1 so you need to account for their input currents as additional load for VOUT1.

Thanks,

Jefferson

• Hi Jefferson,

ok, thanks. The maximum load is 5mA on the buck and 10mA on the inverting buck-boost. I already took that into account that both are powered by VOUT1.

Best regards

Mark

• Hi Mark,

Good to know that both loads for the buck and inverting buck-boost were already considered in your max IOUT1 requirement.

Let us know if you have anymore concerns regarding the ADP103x and were happy to help.

Best regards,

Jefferson