Other Parts Discussed in Thread: LM3534
Tool/software:
Hello,
I am using the LM3435 evaluation kit, and I noticed that as SVDD approaches 1.8 V, the LM3435 is sinking less current into the SDA pin, which limits how low the LM3435 can pull the SDA signal. I have seen this lead to communication errors, as SDA is no longer being pulled low enough for the host micro controller (an i.MX 8M Plus) to receive ACKs from the LM3435. See below for a capture
The following table has a summary of my findings when using a 10 kOhm pull-up
| SVDD | I2C SDA low voltage | Current across SDA Pull-up |
| 1.9 V | 40 mV | 0.186 mA |
| 1.84 V | 400 mV | 0.144 mA |
| 1.8 V | 580 mV | 0.112 mA |
When using a 2.5 kOhm pull-up with SVDD at 1.8 V, the LM3435 is only able to pull the I2C data line down to 1.44 V, corresponding to a pull-up current of 0.114 mA, which tracks with the 10 kOhm measurement of 0.112 mA.
Is this the expected behavior of the LM3435?
Does my evaluation kit have a damaged or otherwise extremely abnormal chip?
What is the minimum pull-up resistance that the LM3435 can reliably use when operating with SVDD at 1.8 V?
