Other Parts Discussed in Thread: DRV401
Hi There,
I am trying to use the DRV411 in the 20-pin SOIC package on my benchtop to prototype a closed loop current sensor. Since I am using an off-the-shelf SOIC to PDIP protoyping board, there is no way to connect the thermal pad on the bottom of the package. So, I've cross checked several times, and it seems that everything is hooked up right. When I apply 5V power, though, the package get extremely hot, and after about 3-5 seconds the output goes from about 2.4V to 1.1V, which I believe may be some protective mode. So first, will this package not work at all without its thermal pad properly heatsinked? Also does the thermal pad NEED to be connected to GND, or can it be floating? I tried to use some thermal paste and a heatsink on the top of the package, but it didn't seem to help. Since the thing gets way too hot I can't safely measure the voltages on all of the pins to understand if perhaps I have connected something incorrectly.
In short, here's what I think is going on (by pin):
1 - REFSEL2 = Vss / GND (refsel 0,0 = 2.5V Voq, nominal)
2 - OVERRANGE = no connection
3 - HALL 1
4 - HALL 2
5 - HALL 3
6 - HALL 4
7 - ERROR = no connection
8 - GSEL1 = 5V via 10k pull up resistor (high gain mode 1000 V/V open loop)
9 - GSEL2 = Vss / GND
10 - Vdd = 5V
11 - ICOMP1 = connected to pin 16 (IAIN2)
12 - ICOMP2 = (secondary) compensation coil negative
13 - Vss / GND
14 - Vss / GND
15 - IAIN1 = (secondary) compensation coil positive and shunt resistor positive (Rs+)
16 - IAIN2 = connected to pin 11 (ICOMP1) and shunt resistor negative (Rs-)
17 - Vout = connected directly to measurement equipment, with high >1M input impedance
18 - Refin = connected via 20 ohm resistor to pin 19 (refout)
19 - Refout = connected to pin 18, and no external connection
20 - REFSEL1 = 0, 0,0 for 2.5V Vouq
So disconnecting just about every device one at a time did not seem to allow the IC to run cool. And it didn't ever seem that the Vref pin, nor the Voq (Vout at Ip = 0A) were ever correct. What's going on?!?!
Any help is greatly appreciated. I'll upload a schematic after dinner and chores ;)
Thanks,
Dave