topic Re: SC18IM700 (UART / I2C bridge) in Digital Signal Controllers

SC18IM700 (UART / I2C bridge)

pdemcenko — Thu, 29 Nov 2018 23:48:11 GMT

The DS of the chip SC18IM700 (UART / I2C bridge) contains no limiting values for Vdd (or I couldn't find any). Please answer:
1. Can the chip function when Vdd is between 3.9 - 5.0 V ?
2. Table 11 in the Datasheet contain Limiting value for an "input voltage" only. What does this "input" mean - Tx and Rx only, or SDA and GPIOx also (these can be programmed for input)?
Thanx!

Re: SC18IM700 (UART / I2C bridge)

graeme_anderson — Mon, 29 Jun 2020 09:24:11 GMT

I have the same question. I have to interface with an I2C device that uses 5V levels.

The SC18IM700 is not interpretting the acknolegment as its Vil = 0.3 * Vdd. Can i operate the SC18IM700 from 5V?

Cheers

Re: SC18IM700 (UART / I2C bridge)

Lorenzo_Mch_IT — Mon, 29 Jun 2020 10:29:14 GMT

In SC18IM700.pdf Section 2 there is a generic description stating "2.4 V and 3.6 V operation"; that's Vdd range.
SC18IM700 is also "5V tolerant on the INPUT pins".

More details are given in section 11 "Static characteristics"::
"Vdd = 2.4 V to 3.6 V; T amb = +40°C to +85°C; unless otherwise specified."

Also from Section 11, looking at Vil and Voh specifications, the "5V tolerant on the input pins" translates into
"completely 5V input tolerant for SDA and SCL ONLY"
because their input voltage ranges from -0.5V to 5.5V (REFERENCED TO Vss), with thresholds at 0.3Vdd and 0.7Vdd.

GPIOs are 5V tolerant too, but with a very important CAVEAT to remember:
in section 9.2.2.1 there is a warning about them when used in quasi-bidirectional mode with 5V inputs that says
"The SC18IM700 is a 3 V device, but the pins are 5 V tolerant. In QUASI-BIDIRECTIONAL mode,
if a user applies 5 V on the pin, there will be a current flowing from the pin to Vdd , causing
EXTRA POWER CONSUMPTION. Therefore, applying 5 V in quasi-bidirectional mode is
discouraged."