ISO5500 ~FAULT pin permament low state

user4079870

Hi,

I try to use ISO5500 in my thesis to control MOSFET. I have a big problem because ~FAULT pin is permament in low logic state and I have -15V in Vout pin (I use 2 voltage sources +15V and -15V).

1. I measured voltage VCC2-VE and it's 15V so it's not a problem.

2. I measured voltage DESAT-VE and it's about zero...

Normally I put on PWM pin signal from microcontroller, but for test I put Vcc on PWM and Vout is always -15V... When I short GND and RES with 1k Ohm I see in my scope some kind of rectangle (between Vout and Ve). But when I put signal from microcontroller on PWM pin and short GND and RES I see irregular rectangle with different width.

Please help, thanks so much!

5736.driver_schem.pdf

3581.driver_board.pdf

over 9 years ago

0 Anant Kamath over 9 years ago

TI__Intellectual 2200 points

Hi,

I am sorry for the delay in this response. I am looking into your issue and will get back to you shortly.

Rgds,

Anant

0 Anant Kamath over 9 years ago in reply to Anant Kamath

TI__Intellectual 2200 points

Hi,

From your schematic, it appears that the drain terminals DRAIN-1 and DRAIN-2 are floating. Is this correct? In normal operation, the gate driver expects that the MOSFET DRAIN voltage is very close to the SOURCE voltage whenever the GATE is high (because the MOSFET turns on). Since you don't actually have the MOSFET, you have to simulate this effect by connecting the DRAIN to SOURCE. Could you please try this and see if it solves your problem?

If it does not, I suggest connecting the DESAT pin to VE directly and trying again.

Rgds,

Anant

0 user4079870 over 9 years ago in reply to Anant Kamath

Prodigy 75 points

Thank You for reply!

Now I am in delegation but I will try your concept as soon as possible - I think tomorrow!

0 user4079870 over 9 years ago in reply to user4079870

Prodigy 75 points

Driver is alive! :)

I connected DRAIN and SOURCE. I have a one more question. Please look at my screen, is this normal that voltage is fluctuate on the top and bottom? On the screen is a max level of deviation.