Digital Signal ControllersのトピックRe: What is the maximum I/O source current per bit for the PCA9698?

What is the maximum I/O source current per bit for the PCA9698?

manuelcaracuel — Mon, 30 Jul 2018 11:25:11 GMT

I would like to use the GPIO expander for I2C bus PCA9698, but I have some limitations of power. At the beginning of the datasheet, it says that at 5 V supply voltage, the outputs are capable of sourcing 10 mA and sinking 25 mA with a total package load of 1 A. Does this mean that the maximum current that can source is 10 mA at 5V supply voltage? Because at the end of the document, appear a graphic that indicates to me that the maximum output source current is greater than 10 mA in some conditions.

Thank you for the answer

Re: What is the maximum I/O source current per bit for the PCA9698?

xiangjun_rong — Thu, 02 Aug 2018 06:20:08 GMT

Hi, Manuel,

Frankly speaking, this is DSC forum, PCA9698 does not belong to DSC family. But your question is a general one, I can help answer it here.

The data sheet says that at 5 V supply voltage, the outputs are capable of sourcing 10 mA and sinking 25 mA with a total package load of 1 A.

From the Fig34 you posted, the GPIO pin can output current more than 10mA, it can reach up to the 40mA for the temperature 25 degree curve, in the case, the VDD-VOH is 0.6V, in other words, if the rail voltage is 5V, the pin output voltage/current is 4.4V/40mA. If the current is 10mA, the pin output voltage/current is 4.9V/10mA.

The Data sheet says that if each GPIO pins output current is less than 10mA, we can guarantee the total package load of 1 A. But if the pin current is out of the range, the total package load may excess 1A.

Hope it can help you

Xiangjun rong

Re: What is the maximum I/O source current per bit for the PCA9698?

manuelcaracuel — Thu, 02 Aug 2018 07:13:17 GMT

Thank you so much Xiangjun for you answer. You helped me a lot.

Manuel

Re: What is the maximum I/O source current per bit for the PCA9698?

manuelcaracuel — Tue, 07 Aug 2018 11:28:04 GMT

Hi again Xiangjun,

I'm sorry to have to write again but I have read your answer again and

there is something in the Figure34 that I do not understand. You told me if

current is 10 mA, the pin output voltage/current is 4.9V/10mA. Does this

mean that if I want an output of 10 mA the Voh shall to be 4.9V? And if

that is so, how can I get 4.9V at the output with a voltage supply of 5V? I

thought that the Voh was set for all supplies, according to the Table 14:

On Thu, Aug 2, 2018 at 8:21 AM, xiangjun.rong <admin@community.nxp.com>

Re: What is the maximum I/O source current per bit for the PCA9698?

xiangjun_rong — Fri, 10 Aug 2018 09:32:01 GMT

Hi, Manuel,

This is my understanding of Fig34, the fig 34 is tested with VDD 5V, the curve means that X coordinator VDD-VOH increase with the Y coordinator source current. For the +25 degree curve,

I VDD-VOH VDD VOH

0mA 0V 5V 5V

8mA 0.1V 5V 4.9V

15mA 0.2V 5V 4.8V

20mA 0.3V 5V 4.7V

26mA 0.4V 5V 4.6V

40mA 0.6V 5V 4.4V

Hope it can help you

Xiangjun Rong

Re: What is the maximum I/O source current per bit for the PCA9698?

manuelcaracuel — Fri, 10 Aug 2018 10:10:28 GMT

Yes I think that you are right. Thank you very much for your help.

Manuel

On Fri, Aug 10, 2018 at 11:32 AM, xiangjun.rong <admin@community.nxp.com>