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PSoC™ 4 Forum Discussions

joli_601446
Level 5
Level 5
10 likes given 10 sign-ins 5 sign-ins

Hello, I am using the Cy8C4244PVI-442 PSOC 4 MCU and have configured it for 5V supply:

PSOC4.jpg

I want to know what will be the output voltage level of the output pins.

I'm looking on page 21 of the datasheet:

PSOC4_io_levels.jpg

Correct me if I'm wrong, but the output voltage for a logic high would be from 3V to 5V.

Am I correct?

Thank you

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1 Solution
Len_CONSULTRON
Level 9
Level 9
500 solutions authored 1000 replies posted 750 replies posted

joli,

I realize it is a bit confusing but let me try to simplify.

In general, Voh is VDDD-0.6V up to VDDD (output current load = 4mA).  If VDDD = 5V then the Voh(min @ Ioh = 4mA) = 4.4V.

If your current load is only 1mA then  Voh is VDDD-0.5V up to VDDD.  If VDDD = 5V then the Voh(min @ Ioh = 1mA) = 4.5V.

Len
"Engineering is an Art. The Art of Compromise."

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3 Replies
Len_CONSULTRON
Level 9
Level 9
500 solutions authored 1000 replies posted 750 replies posted

joli,

I realize it is a bit confusing but let me try to simplify.

In general, Voh is VDDD-0.6V up to VDDD (output current load = 4mA).  If VDDD = 5V then the Voh(min @ Ioh = 4mA) = 4.4V.

If your current load is only 1mA then  Voh is VDDD-0.5V up to VDDD.  If VDDD = 5V then the Voh(min @ Ioh = 1mA) = 4.5V.

Len
"Engineering is an Art. The Art of Compromise."
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joli_601446
Level 5
Level 5
10 likes given 10 sign-ins 5 sign-ins

Thank you very much.

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joli,

You're welcome.

Actually I have better news for you.

For you with VDDD at 5V, Voh will probably be much better.  The actual Voh (with VDDD = 5V Ioh= 1mA) will be closer to VDDD - 0.2V or even VDDD - 0.1V.    This is because the higher VDDD voltage can drive the gate of the output with more voltage lowering the Rds_on of the high FET supplying Voh.

The spec you quoted (SID60) is  Voh (with VDDD = 1.8V Ioh = 1mA).  This provides a Rds_on of (0.5V/1mA) 500 ohms.   At VDDD = 5V the Rds_on is probably closer to 150 ohms.

If you stay with VDDD-0.5V for worst-case, you should be safe.

Additionally, you can parallel GPIO outputs to get increased source/sink current.  This is better if they're on the same port. 

Len
"Engineering is an Art. The Art of Compromise."
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