AM2431: Maximum allowable current for LVCMOS operating at 3.3V

Hello Futoshi

Thank you for the query.

The current range that has been tested has been captured in the LVCMOS electrical specification.

The LVCMOS impedance is 60R.

The configuration that you mentioned may not be an allowed configuration.

Let me check with the expert.

Regards,

Sreenivasa

Hi, Sreenivasa

Thank you for your message.

I appreciate your checking with the expert.

Best regards,

Futoshi

Hello Futoshi

Please refer below inputs from the expert:

We do not expect our output buffers to ever be used in an application that requires it to source any significant DC steady-state current.  We only expect the output buffer to source significant current when the signal is changing logic states.  The only DC steady-state current expected is associated with holding the signal at the opposite logic state of a weak pull resistor.

The peak current that occurs during this contention condition could be very high and may damage one or both devices.  They definitely should not allow the source impedance of the two output buffers to be what limits the current.  They need to resolve the conflict, or at insert a current limiting resistor between the two devices.  However, this current liming resistor may have a significant impact on signal quality if the signal needs to operate with a fast toggle rate.

We do not define a max DC current.  We only define an output current operating condition, where we know the output buffer is able to drive a signal below the VOL limit or above the VOH limit.  They should be okay if they limit the current to less than 3mA, which is the output current operating condition that is being used for the VOH

Regards,

Sreenivasa

Hi, Sreenivasa

I understand that the maximum current has not been defined.

However, since IOH is defined as 9 mA, it should be acceptable up to 9 mA.

Could you please confirm?

7.7.6 LVCMOS Electrical Characteristics

Best regards,

Futoshi

Hello Futoshi

Thank you.

Please refer below inputs from expert:

The below is for the 1.8V supply. You could use the 3.3V current.

Kallikuppa Sreenivasa said:

We do not define a max DC current.  We only define an output current operating condition, where we know the output buffer is able to drive a signal below the VOL limit or above the VOH limit.  They should be okay if they limit the current to less than 3mA, which is the output current operating condition that is being used for the VOH

What is the duration the current draw is expected to be for?

For 3.3V,  the below are the specs that is expected to be followed 

Regards,

Sreenivasa

Hi, Sreenivasa

A current of 30 mA flows for 200 ms.

Is it reasonable to assume that it will not be damaged under these conditions?

Best regards,

Futoshi