STDrive101 Entering fault on boot and not leaving it?

[Charles West]

Hello!

I'm trying to make a open source test board which allows people with an Arduino to try out using the STDrive101 chip. However, I'm running into an issue where it appears to be entering fault mode and refusing to leave it (leaving all mosfets disabled and making the board more or less a brick). I've attached the schematic (and here's the repo with the Kicad project and arduino code https://gitlab.com/charlesrwest/stdrive101testboard ) but I've also put a brief rundown on the setup below:

Operating voltage: 12.3 volts

2 massive 1000uF capacitors to keep source voltage steady

CP set to ground to disable overcurrent shutdown (so CP never higher than Vref)

DT/Mode connected to ground with a 200kOhm resistor (should result in dead time of ~2000 ns).

SCREF left floating to disable Vds monitoring protection

VS has a 100nf bypass cap

REG12 has a 22uF cap and a .22uF cap (seem reasonable?)

NFault left floating, but adding a pullup resistor doesn't seem to change anything (it pulls down)

INH*/IN* and INL*/EN* pins connected to Arduino outputs for control

G*S* pins are connected to their mosfets through 22 ohm resistors

GHS* mosfets have a 2.2uF capacitor between BOOT* and OUT*

Does anyone have an idea why this chip is doing its best impression of a brick?

[Cristiana SCARAMEL]

Hello @Community member​ and welcome to the ST Community.

The VDS monitoring protection - refer to the dedicated section 5.6 in the STDRIVE101 datasheet - is disabled if the voltage is above VSCREF,dis voltage (2.9 V minimum value refer to Table 5).

I think I know where the misunderstanding comes from, we will schedule the datasheet update modifying the SCREF pin description.

I hope this post can help you; if so, consider to mark it as best answer by clicking the label "Select as Best".

[ZY1]

Hi Cristiana, 

Following your advice, I connected the SCREF to 3V3, and indeed, the fault is gone. Nonetheless, there's a problem with the output. The board does not produce the correct output unless I clamp V1 or V3 using the probe's clip while measuring the line voltage. This implies that when I use the probe's clip to clamp V2 or GND for line voltage measurement, the output is incorrect and appears similar to VDS. In addition, I cannot hear the switching noise when the clip does not clamp anything (same as clamp V2 or GND). It quite confused me. Could you please give a guidance? 

P.S. I am using the stm32H7 nucleo board as a control board, instead of the original one. 

[Charles West]

Thank you so much! I connected that pin to 3.3 volts and everything started working perfectly. I've been banging my head against this for a while and I really appreciate it.