TCA8418E: Expected output current

Obinna Ezeilo

Part Number: TCA8418E

Hi Team,

In my customers application, they selected keys that need a minimal current of 1mA.

As stated in the datasheet of TCA8418E, the internall pullups are 55k. So given their supply voltage of 3.3V this would only create a maximum current through the switches of 60µA. From the datasheet, they are not sure what values of output current they could expect on the rows/columns. Is there is some low impedance driving on rows/columns. Will this work?

Thanks in advance for the support.

Regards,

Obinna.

over 3 years ago

0 BOBBY over 3 years ago

TI__Mastermind 49270 points

Hey Obinna,

Can you show us what the schematic looks like?

I'm a bit confused by this: "they selected keys that need a minimal current of 1mA."

Typically keys are just low impedance mechanical switches. When a customer uses the 8418E, its usually as a keypad scanner in which our device will use an algorithm to check to see when a key is pressed. It doesn't necessarily look at the current being sourced/sunk to determine a key press.

Is the customer using our device not in keypad scanner mode? (As an GPIO instead?)

Thanks,

-Bobby

0 Obinna Ezeilo over 3 years ago in reply to BOBBY

TI__Intellectual 2175 points

Hi Bobby,

I can share the schematics offline.

What email should I send it to?

Thanks.

Obinna.

0 Obinna Ezeilo over 3 years ago in reply to Obinna Ezeilo

TI__Intellectual 2175 points

Hi Bobby,

Kindly check your inbox :).

Thx.

Obinna.

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TCA8418E: Expected output current