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# TCA6408A-Q1: what's the power consumption of TCA6408A-Q1 when it's configured as output?

Part Number: TCA6408A-Q1

Hello,

I want to ask what the power consumption of TCA6408A-Q1 is when it's configured as output?

When it's input, the power consumption is low, customer want to keep input & output function normal when SOC powered off, so they want to know the output power consumption of TCA6408A-Q1. I'm not sure how to calculate, pls kindly help this, thank you!

BR,

Daoyan

• Hi Daoyan,

In the datasheet we define the Output high and output low level current for our port pins:

Now when you are talking about power it gets a little tricky because this can change based on if your ports are pulling high or low. On top of that the outgoing logic level of these ports can obviously change and therefore their current consumption can also change.

Typically the best and only thing you can do in this situation is make some predictions and some assumptions about the state of your device. If you have a general idea of how many pins will be inputs and how many will be outputs that  helps with calculating the current. Then if you want you can calculate the worst case current consumption you can say that all your ports will always be outputting low so each one is drawing 25 mA of current.

The next level on top of this is to average this power consumption over time. Lets say 50% of the time your port is output low and then 50% of the time your port is output high. This is not an actual calculation but lets say when you output high you are using 10W of power and when you output low you are using 30W of power. Well over that period of time where the ports are switching you are using an average of 10*.5+30*.5= 20W of power.

Let me know if this helps and if you have anymore questions.

Best,

Chris