SN74AVC4T245RSVR power consumption question?

Chen Bogey8

Other Parts Discussed in Thread: SN74AVC4T245

Hi Sir

we have use SN74AVC4T245 Vcca 3V/Vccb1.8V , we don't understand why when 1A1/1A2/2A1/2A2 input connect high power consumption much lower than one of input pin connect to low(1A2 connect to low and we find 1.8V current have add 5mA)?

Bogey

over 9 years ago

0 Clemens Ladisch over 9 years ago

Guru 316760 points

Where exactly, and how, are you measuring the 5 mA? What is the state of DIR?

0 Nirav Patel over 9 years ago

TI__Expert 6335 points

Chen,

Is it possible that you have 1A1/1A2/2A1/2A2 configured as outputs? If you have a schematic, I'd like to review it.

Best Regards,
Nirav

0 Chen Bogey8 over 9 years ago in reply to Nirav Patel

Mastermind 9990 points

Hi Sir

May you pls refer enclosed file?

remove R7 and series meter.

BogeySIM Board V2P03.pdf

0 Clemens Ladisch over 9 years ago in reply to Chen Bogey8

Guru 316760 points

Footnote 1 of section 6.3 of the datasheet says:

All unused data inputs of the device must be held at V_CCI or GND to ensure proper device operation. Refer to the TI application report, Implications of Slow or Floating CMOS Inputs (SCBA004).

In the schematic, 2B2 is floating.

Replacing R7 (1 MΩ) with a current meter (about 0 Ω) changes the circuit; this does not tell you anything about the current consumption in the real circuit.

And what current is that 1.8 V power supply designed for?

Logic

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SN74AVC4T245RSVR power consumption question?