Hi Sam,
[quote user="Lee, Sam"]Question 1. Is it possible to use this configuration (output from H-Bridge) for the AIN1/2 input of DRV8835 when considering max. 50uA of IIH?[/quote]
Yes, this configuration is possible. The output of the H-Bridge will provide the current required to the input of the DRV8835. The input is high impedance and does not require more the 50uA.
[quote user="Lee, Sam"]Question 2. We’re now confused about the meaning of 50uA, so can you let us know which one is correct in the following statements?
2-1 From current flow point of view,
a. External host is to give the specific current (fixed by external host) to AIN1/2 of DRV8835?
b. DRV8835 is to draw the specific current (required by AIN1/2) from external host?[/quote]
b -- an example is using a 1A power supply to connect to AIN1. The current used by AIN1 is specified by the input circuit.
[quote user="Lee, Sam"]2-2 a. AIN1/2 in DRV8835 need less than 50uA to drive motors?
: In this case, is there any limitation of min. current to make AIN1/AIN2 work normally?
b. AIN1/2 in DRV8835 need more than 50uA to drive motors?[/quote]
2-2 a. Yes, the limitation is based on the minimum current to create a logic high at the input and the input voltage. Assuming the worst case internal 66kOhm pulldown, you will need a minimum of 30uA to achieve a logic high.
2-2 b. Yes, it could use more than 50uA across temperature. The values in the datasheet are at 25C.
In general, use a circuit that can provide at least 1mA to the pin. A 3.3kOhm pullup or a GPIO can do this easily. The input will consume the current needed to operate properly.