Hi Bishara,
1. looking at the typical schematic, SO is connected back to uC. is the purpose of this pin to monitor the voltage at the output gate?
SO is used to monitor the current through the sense resistor. Using an ADC to read the voltage allows the mcu to determine the current.
2. since i am using PWM to control the speed of the motor, I can use IN1 as the control pin is that correct? What would be IN2 connected to?
Based on your question, you intend to use the DRV8701P. IN2 is usually connected to a logic 1 to take advantage of brake mode (slow decay) when running the motor. Please refer to Table 2 for details.
3. since i need at least 25A continues output current to the motor, can i substitute the 50m ohm resistor with 10m ohm? what type of resistor can i use, and part number suggestion?
Yes, the sense resistor can be modified as needed. Please note the sense resistor may need to be lowered to less than 10mOhm because the current * rsense * Av exceeds the minimum AVDD voltage. As an example, at 25A a 7mOhm resistor would produce 3.5V at the SO output, while a 10mOhm resistor would produce 5V.
4. as for the bulk capacitor, the document mentioned to use a number of them if i understood it correctly is that correct? if so, what determines the number of 10uf to use?
The bulk capacitor varies based on the current in the system. At 25A, you will need more than 10uF. Please look at the DRV8701EVM as an example. The EVM is rated for 15A continuous, 20A peak. The schematic and layout are available on line.
1. looking at the typical schematic, SO is connected back to uC. is the purpose of this pin to monitor the voltage at the output gate?
SO is used to monitor the current through the sense resistor. Using an ADC to read the voltage allows the mcu to determine the current.
2. since i am using PWM to control the speed of the motor, I can use IN1 as the control pin is that correct? What would be IN2 connected to?
Based on your question, you intend to use the DRV8701P. IN2 is usually connected to a logic 1 to take advantage of brake mode (slow decay) when running the motor. Please refer to Table 2 for details.
3. since i need at least 25A continues output current to the motor, can i substitute the 50m ohm resistor with 10m ohm? what type of resistor can i use, and part number suggestion?
Yes, the sense resistor can be modified as needed. Please note the sense resistor may need to be lowered to less than 10mOhm because the current * rsense * Av exceeds the minimum AVDD voltage. As an example, at 25A a 7mOhm resistor would produce 3.5V at the SO output, while a 10mOhm resistor would produce 5V.
4. as for the bulk capacitor, the document mentioned to use a number of them if i understood it correctly is that correct? if so, what determines the number of 10uf to use?
The bulk capacitor varies based on the current in the system. At 25A, you will need more than 10uF. Please look at the DRV8701EVM as an example. The EVM is rated for 15A continuous, 20A peak. The schematic and layout are available on line.