TPS70950DBVR Voltage Regulator Issues

Using Arduino General Electronics
#1

It just smoked.
I’ve been operating and testing this PCB with a bench top power supply (13.8 VDC), and all has been well. When I hooked it up to my 18VDC battery, (20.1VDC), it smoked this 5.0 VDC regulator. According to THE DATA SHEET this regulator is made for input voltages from 2.7 to 30 VDC, so I thought I was fine. I see now the data sheet says,

Power dissipation depends on input voltage and load conditions. Power dissipation (PDISS) is equal to the product of the output current and the voltage drop across the output pass element, as shown in Equation 1:
PDISS = (VIN – VOUT) × IOUT
(1)

Ok, so I’ve got a 25 volt drop, and the current, well, I’m guess it’s less than 50ma. It’s just the Atmega328 chip, and a motor controller IC, which I think draws 5-8ma, and an LED drawing about 12ma. I couldn’t really find anything else in the data sheet that tell you how much power dissipation it can handle. It looks like it’s all based on thermal junction temp.

There’s also another identical regulator onboard, only it puts out 3.3VDC for an RF chip. It was not fried. It too is powered from the same 20VDC, but it lost power once the trace at the 5.0v regulator burnt up.

I’ll include a photo of the PCB trace/copper, and the board. If anyone can shed some light on this. Do I need 1) a different regulator? 2) different trace/copper/heat dissipation 3)are my high voltage traces too close to other? I’ve got 10mil clearance on all traces.

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#2

To simplify my question, I ran a test on a new pcb. I populated just the regulator and 2 caps as suggested in the data sheet. I powered it with a 13.8V bench top power supply and hooked up LEDS with their respective resistors to the output of the regulator. 4 LEDS drew about 38mA and then I checked the temp of the regulator with a K-type thermocouple. It raised the temp about 5 degree Celsius -- to about 40 degrees. Then I removed some LEDS so it was only drawing 18mA, and replaced the 13.8 volt power supply with the 18 volt (20.1 volt actual reading) lithium battery pack from my drill, and immediately the voltage regulator smoked again.
I may be slow to catch on, but I don't think this regulator can operate on 30VDC like the datasheet says. I mean, I was only drawing 18mA.
Unless I'm missing something here?
Again, here is the data sheet for this regulator

And here is the exact part I'm using from Digikey

The attached images show the PCB board and copper.

#3

I don't see any supply decoupling on the board.

Long shot. Read this:

Leo..

#4

The data sheet called for a 1uF cap on the input and a 2.2uF on the output. I have both of those in place, as seen in the photo

#5

I found in the evaluation board data sheet that it say for their board, the maximum Vin is only 6.5V.

#6