Tool/software:
Hello,
The DS160PR412 has four-level control inputs.
I would like to put it into I2C mode by setting the MODE pin to L1 or L2 (but not L3 because that is a reserved mode).
I can not rely on the internal pull-up resistor/current to set the MODE pin; I must use an external pull-up resistor instead.
What external pull-up and pull-down resistor values should I use to overpower the internal pull-up and set MODE to I2C mode?
An example, which may or may not match reality:
- Per datasheet, the settings are (to GND) Rd: L0 = 1kΩ, L1 = 13kΩ, L2 = 59kΩ, L3 = Float.
- Assuming the devices uses the following voltage levels V: L0 = 0V, L2 = 1.1V, L3 = 2.2V, L4 = 3.3V
- Using L2 and L3 levels to calculate pull-up resistance (Ru = Rd/(V/3.3) - Rd): L0: 26kΩ & L3: 29.5kΩ -> so maybe the internal pull-up resistance is ~28kΩ
- To overpower the internal pull-up resistance, use external resistors < 28kΩ/10 = 2.8kΩ.
- Targeting a level between L1 and L2 to achieve most resilient voltage level: 1.65V -> Is this a bad idea? (does the chip have Schmitt inputs?)
- Use a pull-up of 1kΩ and pull-down of 1kΩ
- Final value assuming 28kΩ pull-up: 1.68V
- Final value assuming the 28kΩ pull-up degrades to 28kΩ/5: 1.79V
