Sla 7062m Vref

[sierra]

Hi,

Just got sla 7062m board ready, and did some testing..... now i got a problem. Can´t get vref lower than +2.15vdc.. i try to use 1Amp motor, so i think i must get 0.25 to vref to be correct, a´m i right? i have those sense resistor .47 ohm 5W.

i really dont know where to star to solve this one.
i got 29V input, via zener so at lm317T i got 5.2 at output (middle leg) at 74hc14 i got 5.2. sla has 5.2 in leg nro 6.

I didn´t got bss92 so i used bss84 at lover side of pcb. i have gate of bss84 at next from 74hc14.

Can some one help me here?

Thanks

-Jarkko

[PMinMO]

You can't get it lower than ~2V because the BSS92 is on. You have to enable the board by grounding pin 1 of the idc connector. Vref is the motor current times the sense resitor value.

[sierra]

Thanks!

I did think that it has to be the bss84, wich cause the problem by staing high. but didn´t see that enable pin....now it does work!
Using 4 0.47ohm resistor and 1 amp motor i use 1amp x 0.235 to get vref on 0.235.

Best Regards
Jarkko