BOOSTXL-DRV8305EVM: Is there a problem with the driver board?

Hi Annie,

Are you just trying to evaluate MOTC = VM = 24V when applying INHC = 3.3V and INLC = GND?

For gate driver outputs to work and see switch node outputs switch to VM, you need to apply a resistive or inductive load to MOTC and GND or else the MOTC current cannot sink. 

Thanks,
Aaron

Hi Aaron,

Input 6 PWM signals to 8305 driver board. Use MOTC and GND as the terminal of the oscilloscope. The measured voltage should be 0 and 24V alternately. The other two phases MOTA and B are all pulse voltages of this kind, only MOTC is not. The display of MOTC is always 24V。 Customer would like to know how to resolve it?

Thanks,

Annie

Hi Annie,

Thanks for your patience. Aaron will get back to you shortly.

Thanks,

Matt

Hi Annie,

To see MOTC rise to 24V, you will either need to source or sink current through phase C.

If sourcing current through MOTC, make sure that INHC = 1, INLC = 0, and there is a resistive or inductive path to another phase (MOTx), then make sure INHx for that phase = 0 and INLx for that phase = 1. So the current path is VM --> MOTC --> MOTx --> GND. Or you may use a resistive or inductive load from MOTC to GND.

And vice versa if you are sinking current through MOTC. 

Is the customer using any load when applying the PWMs?

Thanks,
Aaron

Hi Aaron,

There is no load used. C-phase PWM has high and low levels, but MOTC is always high level 24V. May I know is the triode turned on, or what is the problem?

Thanks,

Annie

Hi Aaron,

Yes, do the same operation, the customer's MOTC=24, the value of MOTC is always 24V instead of 0 and 24V.He would like to know how should this be solved?

Thanks,

Annie

Hi Annie,

Has the customer tested their setup on another BOOSTXL-DRV8305 or DRV8305-Q1EVM to see if it works? PWM inputs look fine, but then blue PWM signal has very small PWM voltage output (I'm assuming when device is enabled, WAKE = ENABLE = 3.3V). 

This should be a simple test, but it is possible that the INLC is getting pulled down to GND internally since it cannot rise to the PWM voltage. There is 100k internal pulldown resistor on INHx/INLx. If drive strength is sufficient for INLC, then possibly a short to GND has occurred, especially since MOTA and MOTB switches correctly.

Thanks,

Aaron

Hi Aaron,

Yes, they bought two BOOSTXL-DRV8305 via ti,com in total. It is effective to use another block to test in the same way, that is, 0V and 24V alternating pulse signals appear in all three phases. This is indeed a simple test, mainly used for the preparation test before connecting the motor. He would like to know how should the problem of this board be solved now?

Thanks,

Annie

Hi Annie,

Aaron will get back to you shortly

Thanks,

Matt

Hi Annie,

So MOTx toggles correctly on the second unit when INHx = 1 and INLx = 0?

Can customer run impedance check between INLC and GND?

Thanks,
Aaron

Hi Aaron,

When INHx = 1 INLx = 0, it is switched correctly in MOTB

When he measured INHC=0 and lNLC=1, MOTC should be 0v, but the measured value is still 24v.

If INLC and GND are tested for impedance, the resistance is only four or five ohms.

Thanks,

Annie

Hi Annie, 

There is the issue, resistance between INLC and GND should be ~100k (see below)

When and where was this board ordered from? Did the customer mishandle this board in any way before testing? Can the customer send the lot number of the device on the IC in the case if its a device issue from a specific lot?

We can send another board to the customer if they would like on behalf of TI. 

Thanks,
Aaron

Hi Aaron,

Customer bought it on ti.com and order number is T01157957.

Thanks,

Annie

Hi Aaron,

I have accepted your friend request.

And I also contacted with CSC team, they will help to assign this replacement case to ecommerce team to follow up. 

Thanks for your help.

Annie