Hello. I don't have enough experience to make an informed judgement about this:
I'm using a 5W 6.8V Zener diode to shunt 600 mA. datasheet:http://61.222.192.61/mccsemi/up_pdf/SMBJ5338B-SMBJ5369B(SMB).pdf
It needs to do this at a frequency of about 2 Hz with a duty cycle of 50%. ie. it is shunting the current half the time and each pulse lasts about 0.25 seconds.
The datasheet says the maximum Zener current is 700 mA. If I understand correctly, the power at that current is 6.8V x 0.7A = 4.76W. I'm shunting 600 mA or 4.08W, so about 85% of the maximum rated Zener current.
Again, if I'm interpreting the datasheet correctly, shunting 600 mA at 50% duty cycle should be OK. The diode's ground lead is connected to the ground plane on the PCB, which is probably a little over 1" square.
My lack of experience is making me doubt my design and wonder if I'm pushing this diode too far. It gets very hot when shunting the current. Hotter than I would expect considering its only doing it half the time. Should I add a heat sink to the package? Is it bad design? An alternative way to shunt the current is going to be complicated.
Should I trust the datasheet and just go with it?
I'm using a 5W 6.8V Zener diode to shunt 600 mA. datasheet:http://61.222.192.61/mccsemi/up_pdf/SMBJ5338B-SMBJ5369B(SMB).pdf
It needs to do this at a frequency of about 2 Hz with a duty cycle of 50%. ie. it is shunting the current half the time and each pulse lasts about 0.25 seconds.
The datasheet says the maximum Zener current is 700 mA. If I understand correctly, the power at that current is 6.8V x 0.7A = 4.76W. I'm shunting 600 mA or 4.08W, so about 85% of the maximum rated Zener current.
Again, if I'm interpreting the datasheet correctly, shunting 600 mA at 50% duty cycle should be OK. The diode's ground lead is connected to the ground plane on the PCB, which is probably a little over 1" square.
My lack of experience is making me doubt my design and wonder if I'm pushing this diode too far. It gets very hot when shunting the current. Hotter than I would expect considering its only doing it half the time. Should I add a heat sink to the package? Is it bad design? An alternative way to shunt the current is going to be complicated.
Should I trust the datasheet and just go with it?