SN74LVC1G17: ICC current

Daisuke Higa

Genius 4340 points

Part Number: SN74LVC1G17
Other Parts Discussed in Thread: SN74AUP1T17

Hi support team all.

I have asked from my customer regarding value of Icc current when use case is UART.

They are inputting UART signal (35kHz).

They measured the ICC current and found it to be approximately 1.2mA.

From the datasheet's input frequency vs. ICC graph, it is approximately 13MHz@VCC=3.3V that exceeds 1mA. I think 1.2mA at 35kHz is a very large current, what do you think about this?

Best regards,

Higa

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 316920 points

What are the supply and signal voltages?

0 Daisuke Higa over 1 year ago in reply to Clemens Ladisch

Genius 4340 points

Hi Ladisch-san

Thank you for your reply.

VCC is 3.3V, Signal is UART 0V to 2.2V(TTL level).

I received the additional question from my customer.

Another device's Icc is 0.4mA under the same conditions.

There is a large variation. Is this the correct result?

Regards,

Higa

0 Clemens Ladisch over 1 year ago in reply to Daisuke Higa

Guru 316920 points

2.2 V is not TTL. And when the input voltage is not near the rails, the supply current indeed increases; see the ΔI_CC specification and [FAQ] How does a slow or floating input affect a CMOS device?

Use a level shifter like the SN74AUP1T17.

0 Daisuke Higa over 1 year ago in reply to Clemens Ladisch

Genius 4340 points

Hi Ladisch-san

Thank you for your confirming.

I understood.

Thanks.

Regards,

Higa

0 Daisuke Higa over 1 year ago in reply to Daisuke Higa

Genius 4340 points

Hi Ladisch-san

I received an additional question from my customer.

Could you please tell me how to estimate the current consumption?

Signal input is 0V-2.2V UART: 35kHz. Power supply voltage is 3.3V.

Since SN74AUP1T17 allows input from 0V to 1.8V, we believe that the current is close to the Icc specified below.

However, since the condition for this spec is Io=0, could you please tell me how to estimate the current consumption when driving a load?

Best regards,

Higa

+1 Owen Westfall over 1 year ago in reply to Daisuke Higa

TI__Genius 12891 points

Hi Daisuke,

Please see [FAQ] How do I Calculate Power Consumption or Current Consumption for my CMOS Logic Device?

Let me know if you still have questions.

Regards,

Owen

Logic

Logic forum

SN74LVC1G17: ICC current