SN74LVC1G07-Q1: Port In/Output minimum current

Charles Jeon

Expert 2975 points

Part Number: SN74LVC1G07-Q1
Other Parts Discussed in Thread: SN74LVC1G14-Q1, SN74LVC1G17-Q1

Hi team

I am trying to design the circuit as shown below.

VCC discharge from 3.3V to 1.8V, because power is coin battery.

I want to administrate system to low power consumption.

So, I selected pull-up resistor by 300kohm.

Is there a problem when applied a large value pull-up resistor as above?

Is there a minimum current required for accurate input and output?

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 243220 points

The SN74LVC1G07-Q1 does not have a Schmitt-trigger input; 300 kΩ at its input would make the signal edges too slow.

The SN74LVC1G14-Q1 has a Schmitt-trigger input and does not require any minimum speed. It does not have an open-drain output, so it does not need a pull-up resistor at its output.

If you want a non-inverting buffer, use the SN74LVC1G17-Q1 instead.

0 Charles Jeon over 4 years ago in reply to Clemens Ladisch

Expert 2975 points

Hi Clemens

I need open-drain output.

Is output no problem when used high value pull-up resistor?

0 Clemens Ladisch over 4 years ago in reply to Charles Jeon

Guru 243220 points

The circuit shown does not need an open-drain output.

Why does your secret actual circuit need an open-drain output?

0 Dylan Hubbard over 4 years ago in reply to Clemens Ladisch

TI__Mastermind 42600 points

Hi Charles,

2 things here. The schematic has an inverter with schmitt trigger inputs and push pull outputs. That device won't need a pull-up. A device with open-drain outputs will need a pull-up to drive High.

300K ohm is fine on the output, it will depend on the system requirements, for instance " how fast does the slew rate need to be for the following device".

The 300K ohm at the input may be too large to achieve the required rise time. Using 10K may be better to provide faster rise time.

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SN74LVC1G07-Q1: Port In/Output minimum current