SN65HVD10-EP: Maximum current consumption

Prasittichai Tamkhoksung

Tool/software:

Hello,

I would like to know the max current consumption of RS-485 TRANSCEIVERS for using in our power supply
If power supply 3.3V 50mA, it that enough?

Could you pls send me the suggestion?

Best Regards,

Prasittichai

over 1 year ago

+1 Clemens Ladisch over 1 year ago

Guru 320110 points

The supply must also provide the current that flows through the cable and the termination resistors. Figure 13 shows that you should aim for 75 mA or 100 mA.

If it is possible that the output gets shorted, and you want the supply to not drop out in this case, then it must be able to handle 250 mA.

+1 Ethan Sempsrott over 1 year ago in reply to Clemens Ladisch

TI__Mastermind 18832 points

Hi Prasittichai,

I would recommend a supply that can support 250 to 300mA in case there is a short on the bus. 75 to 100mA would supply the device properly, but the risk is the power supply could collapse during a bus short. Either way, a power supply larger than 50mA is necessary.

Best,

Ethan

0 Prasittichai Tamkhoksung over 1 year ago in reply to Ethan Sempsrott

Prodigy 10 points

Hi Ethan,

thank for suggestion.

I have additional questions.

If my power supply can be supply current around 75-100 mA and ignore in case short circuit.

Is my power supply sufficient to operate in a normal case?

Best Regards,

Prasittichai

0 Clemens Ladisch over 1 year ago in reply to Prasittichai Tamkhoksung

Guru 320110 points

Yes.

+1 Ethan Sempsrott over 1 year ago in reply to Prasittichai Tamkhoksung

TI__Mastermind 18832 points

Prasittichai,

Yes, that will work. Below is Figure 13 from the datasheet which shows a typical current draw at the respective VCC and signaling rate.

Regards,

Ethan

0 Prasittichai Tamkhoksung over 1 year ago in reply to Ethan Sempsrott

Prodigy 10 points

Hi Ethan, Clemens,

Thank you for suggestion.

Best Regards,

Prasittichai

0 Prasittichai Tamkhoksung over 1 year ago in reply to Ethan Sempsrott

Prodigy 10 points

Hi Ethan,

If a signal rate at 1200 bps @3.3V, typical supply current around 4x.xx mA or right?

RMS means root mean square ?

Best Regards,

Prasittichai

0 Clemens Ladisch over 1 year ago in reply to Prasittichai Tamkhoksung

Guru 320110 points

Yes, you are using 0.001 Mbps.

These are typical values, so you should have safety margin. 50 mA might work when testing in the lab, but I would not feel good about it.

The current depends on the actual signal to be transmitted, so the graph mentions RMS to say that the current is averaged in some way. This is not an AC supply, so negative currents cannot happen.

0 Ethan Sempsrott over 1 year ago in reply to Prasittichai Tamkhoksung

TI__Mastermind 18832 points

Prasittichai,

Yes, RMS means root mean square.

This graph should not be taken as a defined electrical characteristic. These results can vary from device to device, and your test environment will vary as well. You still need a higher supply current during boot up and mode changes than what is listed on the graph. The graph only demonstrates steady operation.

I would still recommend ~75mA.

Regards,

Ethan

0 Prasittichai Tamkhoksung over 1 year ago in reply to Ethan Sempsrott

Prodigy 10 points

Dear Ethan,

Do you have a current profile during communication boot up and mode change?

Best Regards,

Prasittichai

0 Ethan Sempsrott over 1 year ago in reply to Prasittichai Tamkhoksung

TI__Mastermind 18832 points

Prasittichai,

This specification is not given as it can vary from setup to setup. It is to be best to be tested on your individual setup.

Regards,

Ethan

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SN65HVD10-EP: Maximum current consumption