TLV1811: sink current

Fred Cheng

Expert 4700 points

Part Number: TLV1811

Hi team,

this curve mean the sinking current under different output voltage , right?

so does this mean the sinking current will gradually decrease as the output voltage drop to 0?

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 244850 points

This is not about switching, but about the DC behaviour.

In practice, the output load requires a certain current, and that results in a certain voltage. When the output drives low, but must sink current to do this, then the voltage drop between the output and GND is larger with larger currents. (A MOSFET behaves pretty much like a plain resistor, but saturates at large currents.)

In other words, when you connect a 100 Ω pull-up resistor to the output, the output voltage will be higher than with a 10 kΩ resistor.

0 Fred Cheng over 1 year ago in reply to Clemens Ladisch

TI__Expert 4700 points

Hi Ladisch,

I know it's DC behavior,

but it also tell us the dynamic behavior,

if we match the DC curve frame by frame.

for example, if only a output cap is connected.

and the voltage start to be sinked by comparator,

the sink current will gradually become smaller as the output dropping, right?

and eventually drop to around 100uA

0 Clemens Ladisch over 1 year ago in reply to Fred Cheng

Guru 244850 points

Yes; if you use the output to discharge a capacitor, the voltage will fall like in an R-C circuit.

0 Fred Cheng over 1 year ago in reply to Clemens Ladisch

TI__Expert 4700 points

HI Ladisch,

speaking of RC,

can I assume the slope of the curve is that "R" resistor?

0 Clemens Ladisch over 1 year ago in reply to Fred Cheng

Guru 244850 points

Yes. (When the transistor saturates, the slope is no longer constant.)

+1 Fred Cheng over 1 year ago in reply to Clemens Ladisch

TI__Expert 4700 points

Hi Ladisch,

thanks a lot.

I know it only valid at linear region of MOS.

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TLV1811: sink current