DRV10975: Help to evaluate drv10975rhfr / vqfn: the system is powered by 12V, and the output power consumption is about 2.2W (several hundred MA); at the peak, the system will have 2.5A current in an instant

Hi,

Thanks for posting in E2E forum. Please see my responses below.

1.1 Pin 4 I think some reference designs are connected with inductors and some are resistances. Please help to confirm!

Pin 4 is Step-down regulator switching node output. Step down regulator is configured in buck mode when an inductor is connected and in linear mode when resistor is connected. 

1.2. Does pin4 need a diode? If so, what is the role? (I think some references are connected; some are not connected with diodes.

 Pin 4 doesn't need a zener diode as the output voltage of this pin is already regulated by the step down regulator.    

2. How to design pin5? (I see the reference design, some are directly grounded, some are connected to capacitors)

Pin 5 is Step down regulator ground. I am not sure which reference design you are referring to. But pin 5 should be connected to ground. 

3.1. Is pin9 the internal output voltage of the chip 3.3V? Can this voltage supply the external u41 U60? (u41 U60 is a level conversion chip, which is also ti's)

Pin 9 is the internal 3.3V supply voltage. Maximum load current that V3P3 can supply is 5 mA. Please check the datasheet of U41 to make sure load current is not more than 5 mA. If it is more than 5mA then you will not be able to use the 3.3V internal power supply from the device.   

3.2. When I check the specification, there will be 1.8V and 3.3V voltage output inside the chip? Which pin does the two voltages correspond to?

Yes, this device has two internal LDOs supplying 1.8V (Pin 7) and 3.3V (Pin 9).  

4. Pin10 pin11 / SCL SDA communicates with I2C on the other side. The voltage is unbalanced. Is u41 OK? (as shown below)

I see SDA and SCL pulled high to 3.3V which is okay. Again check with U41 as mentioned previously. 

5.1. Pin12 FG is connected to our Bluetooth chip, but the Bluetooth chip is a 1.8V I / O port. Can I / O port of Bluetooth be directly connected to pin12 FG? Or it needs to be designed as shown in the figure below. It needs to add level conversion chip U60 to connect the two side network?

I am not sure which Bluetooth chip you are referring to. FG is an output pin. When HIGH the output voltage (min) is 2.2V and when low the maximum voltage is 0.65V. 

5.2. Does pin12 FG need pull-up resistance?

Yes.

6.1. Pin13 speed is connected to our Bluetooth chip MTL? PWM network. But Bluetooth chip is a 1.8V I / O port. Can I / O port of Bluetooth be directly connected to pin13 speed? Or it needs to be designed as shown in the figure below. It needs to add level conversion chip U60 to connect the two side network?

Are you commanding the speed via I2C? If so, then I don't understand why SDA2 is mapped to Speed. The Speed Command can be controlled in one of three ways. You can set the Speed Command on the SPEED pin by adjusting either the PWM input (SPEED pin configured for PWM mode) or the analog input (SPEED pin configured for analog mode), or by writing the Speed Command directly through the I2C serial port to SpdCtrl[8:0].

6.2. Does pin13 speed need pull-up resistor?

No.

7. What is the function of PIN14 dir? Do you need to pull up or down? If necessary, pull up or pull down? Do you need anything to control it?

DIR is the direction control input pin. Yes, a pull up resistor is required.

8. Is the pin15 pin16 directly connected to the earth when routing, or is it led out to the designated earth separately?

Pin 15 and 16 are Power ground. I am not sure why an LED is required there. I can be directly connected to the ground. 

9. Is there any problem with pin17 ~ pin21? Are beads in series required? Shunt capacitor? Wait...

I don't understand what you are trying to ask!

10. Have the capacitance values of pin23 and pin24 for capacitors met the above power operating conditions?

A 10 uF decoupling cap is needed across Vcc and GND.

11. Ask pin12 FG again. If the conversion level chip is used, what is the maximum frequency that FG can support? How many frequencies can pca9306 support under corresponding conditions? (we are worried that the signal transmission of FG can not keep up with the demand

I am not sure why FG is connected to SCL. SCL is the I2C clock signal and FG is an output pin that gives the speed feedback. Can you check this again?

Regards,

Vishnu