SN74ABT541B: IQ Current

Brian Wang0928

Genius 14770 points

Part Number: SN74ABT541B

Tool/software:

Customer would like to know the quiescent current of the device. and in the d/s, we're confused below.

When output is LOW, the IQ is 30mA that is much higher than when Output is HIGH, why? Or it's typo on unit?

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 320330 points

I_CC measures the current flows into V_CC and out of GND.

When the output is high, the current that flows into Q2's and Q3's bases flows into the load (if there is one).
When the output is low, the current that flows into Q4's base flows into GND.

0 Brian Wang0928 over 1 year ago in reply to Clemens Ladisch

TI__Genius 14770 points

Thanks. More questions are here.

1. When OUTPUT LOW, the ICC is 30mA specified in the d/s. It means every channel consuming about 30mA/8 =3.75mA, correct?

2. For the IOH parameter, it should be souring current, correct? why it's -32 mA, not +32mA?

3. Are IOH and IOL parameters for each channel current? 64mA/ch, total is about 8 *64 = 512mA, correct?

Regards

Brian

0 Malcolm Lyn over 1 year ago in reply to Brian Wang0928

TI__Mastermind 30220 points

Hi Brian,

That is not correct. See this picture: Icc is tested with all outputs open.
Conventionally, current flowing out of the device is marked as negative and current flowing into the device is marked as positive.
Yes, these parameters are for each channel.

Best,

Malcolm

0 Clemens Ladisch over 1 year ago in reply to Brian Wang0928

Guru 320330 points

1. Yes, the 30 mA is for when all eight channels are low. R1 appears to be 1.8 kΩ typical.

0 Brian Wang0928 over 1 year ago in reply to Clemens Ladisch

TI__Genius 14770 points

Thanks. I'd like to clarify something here.

- When Output is in LOW state, the M1 and Q4 of the circuit are turned ON. It means all eight CH are LOW state, and the ICC consuming about 30mA,max, right?

- In the d/s, it says the Latch-up Exceeds 500mA as below diagram.

a. What's the senario of this exceeds 500mA? It is for the output channel shorting to Ground? Or is it related to the ICC (Input Current)?

b. When current is exceeding 500mA, what happened? device is disabled or any protection?

0 Clemens Ladisch over 1 year ago in reply to Brian Wang0928

Guru 320330 points

1. Yes.

2. See the Latch-Up White Paper. Current is injected into the pin; this usually requires violating the valid voltage ranges. Latch-up cannot happen when you stay inside the absolute maximum ratings.

0 Brian Wang0928 over 1 year ago in reply to Clemens Ladisch

TI__Genius 14770 points

For the Latch-up, could this behavior happen on every pin? Are VCC pin, or any pin able to be Latch-up when outside of the max. voltage rating?

Regards

Brian

0 Clemens Ladisch over 1 year ago in reply to Brian Wang0928

Guru 320330 points

This is usually only a concern for input pins. But if you exceed the voltage at other pins, the device might get damaged due to other effects.

Latch-up is a concern when you are testing a device. But for practical purposes, you need to care only about the absolute maximum ratings.

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SN74ABT541B: IQ Current