MK64 I2C: Do I/O Pins Configured as I2C Open-Drain Meet I2C Bus Spec. Vol = 0.4V @ 3mA Sink?

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MK64 I2C: Do I/O Pins Configured as I2C Open-Drain Meet I2C Bus Spec. Vol = 0.4V @ 3mA Sink?

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dgpace2
Contributor I
I'm using an MK64FN1M0VLL12 as the Chassis Manager in a System Management Bus Architecture. The System Management Bus uses (2) I2C interfaces [IPMB-A and IPMB-B]. I use Pin G11 configured as I2C0_SCL and Pin G10 configured as I2C0_SDA for the IPMB-A Interface. I use Pin C6 configured as I2C1_SCL and Pin C5 configured as I2C1_SDA for the IPMB-B Interface. The System Management Bus is Operating in Multi-Master Mode as per I2C Specification. All (4) Pins [G11, G10, C6, and C5] are configured as Open-Drain Pins. The I2C Specification sets Vol = 0.4V {Max.} @ 3mA Sink. When I look at the Electrical Characteristics in the Kentis K64F Sub-Family Data Sheet [K64P144M120SF5, Rev. 7, 11/2016] I see under Table 4 [Voltage and Current Operating Behaviors] that Vol = 0.5V {Max.} @ 9mA Sink when 2.7V < Vdd < 3.6V when I/O Pins are configured as High Drive Strength. When I configure these (4) Pins [G11, G10, C6, C5] as Open-Drain Pins, will these Pins meet the I2C Specification of Vol = 0.4V {Max.} @ 3mA Sink or will these Pins Operate with Vol = 0.5V {Max.} @ 9mA Sink when 2.7V < Vdd < 3.6V? In Summary, is there a specification for I2C Capable I/O Pins [Vol = 0.4V {Max.} @ 3mA Sink] Configured as Open-Drain, different from the GPIO Specification listed under Table 4 [Vol = 0.5V {Max.} @ 9mA Sink]? I need the additional 100mV of Noise Margin Preserved on these Pins when they are "Driving" the I2C_SCL and I2C_SDA Pins Out [0.4V as per I2C Spec. versus 0.5V which is listed in the Data Sheet].
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nxf54944
NXP TechSupport
NXP TechSupport

The table says that an output voltage higher than the 0.5V is not consider output low voltage. 0.4V is considered as Vol, so when the Vdd is between 1.71V and 2.7V and it is configured as high drive strength the Iol is 3mA.
The I2C module supports System Management Bus so the device can behave as the SMBus requires.

If you have more questions do not hesitate to ask me.
Best regards,
Omar

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nxf54944
NXP TechSupport
NXP TechSupport

Hello

The I2C module complies with the System Management Bus (SMBus) Specification, version 2. In the datasheet, table 4. The value of 0.4V in symbol VOL is included since the maximum range for VOL is 0.5V.

Let me know if this is helpful, if you have more questions do not hesitate to ask me.
Best regards,
Omar

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dgpace2
Contributor I

Omar, can you "Please" Verify that when the I/O Pins are Configured as Open-Drain and used for a System Management Application, that Vol will be 0.4V "Maximum" as long as Sink Current is "Less Than" or Equal to 3mA Sink?

In other words, I will "NEVER" see Vol = 0.5V in System Management Applications.......Correct?

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dgpace2
Contributor I
Thanks Omar, So the Data Sheet says Vol = 0.5V "Max.". I just want to double check......when Configured as Open-Drain......used in my System Management Bus Application...….Vol = 0.4 "Max." as long as Sink Current is "Less" than or Equal to 3mA. Correct? In other words......I'll "NEVER" see Vol = 0.5V "Max." in System Management Applications?
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nxf54944
NXP TechSupport
NXP TechSupport

The table says that an output voltage higher than the 0.5V is not consider output low voltage. 0.4V is considered as Vol, so when the Vdd is between 1.71V and 2.7V and it is configured as high drive strength the Iol is 3mA.
The I2C module supports System Management Bus so the device can behave as the SMBus requires.

If you have more questions do not hesitate to ask me.
Best regards,
Omar

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