CGD1700HB2M-UNA Test

epool

Hello,

I am currently trying to test the CGD1700HB2M-UNA board without MOSFETs connected at the output, that is, the Gate-Source connections of High and Low devices of the board are floating (connectors JB2 and JB3). Because of the floating output, it seems that the board sends a fault "state" that disables the output signals.

Is there any way to operate the board while the outputs are floating?

Another feature I am not sure if I am setting correctly is the RESET/EN functionality located in Pin 15 from connector JT1 (JT1 is located at the CGD1700HB2M-UNA board). According to TI UCC21710 datasheet (attached), that PIN is needed to enable the output of the gate driver. I have set this connection to 5V. Is this correct? Or maybe this is also generating a fault condition? What should be the correct setting for this connection?

Thanks

cpwr_an46_cgd1700hb2m_una_application_note.pdf

ucc21710.pdf

CGD1700HB2M-UNA Schematic Rev A.pdf

AustinC

Hi epool,

Yes, you can operate the CGD1700HB2M-UNA gate driver with the outputs floating. You'll need to ensure that the overcurrent protection connections are properly made; otherwise, the gate driver will immediately trip an overcurrent fault and stop switching.

The low-side spade connector, JT4, should typically be connected to the low-side drain (the midpoint) to enable overcurrent protection, but for your disconnected, benchtop testing, JT4 should be connected to the low-side source. The high-side has the same requirement; during normal operation, the spade connector, JT5, should be connected to the high-side drain (V+), but for your testing, JT5 should be connected to the high-side source. This will prevent the LS & HS overcurrent circuits from charging up and triggering a fault condition.

You are correct, the Reset/Enable pin on the UCC21710 should be held high to enable the driver outputs. You can leave the RESET input to the board floating as there is a pull-up resistor on the gate driver board or pulling it up with 5 V is also acceptable as you are presently doing.

Best Regards,

Austin C.

epool

Austin,

Thank you for your reply. I was able to run the board with the connections indicated.

I have some additional questions.

From the board schematic, I can notice that the high and low side gate drivers are completely independent and each one has its own power supply, protection, etc.

Does that mean that I can use the high and low gate drivers interchangeably? Or is there any circuit in the board that might not allow this? (or any feature that might not work properly if this is done?)

For example, in a half-bridge, Could I use the named "low side" for my top MOSFET and "high side" for my bottom MOSFET ?(of course considering the corresponding drain connection of JT4 and JT5 when the overcurrent protection is used)

Thanks.

AustinC

Hi epool,

You are correct; on the CGD1700HB2M-UNA, the high-side and low-side channels are completely independent and can be used interchangeably. You could use the channel named low-side for your top MOSFET and the channel named high-side for your bottom MOSFET.

Best Regards,

Austin C.

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.