Hello all,
I woroking on my senior design for college and have a question about the H-bridge I've built. The set-up is similar to the one at this link:
http://www.parallax.com/dl/docs/cols/nv/vol2/col/nv52.pdf
Changes:
1) I have a +24V supply running to the top of the h-bridge instead of his power supply.
2) R1 and R2 are 100k resistors, not 120k
3) C3 and C4 are 0.033 uF (This is still 10 times the input capacitance of FET and should be fine)
4) D4-D7 are 13V zeners not 15V (Does not change much of anything)
5) R4-R7 I had set at 10ohm, and then 51ohm which lead me to my problem, btw these are 1/4W as well.
Problem:
I have the HIP4081A and surrounding circuitry running fine. I can use a scope to see the switching on the two Mosfets I need when the Fets are not attached. The gates voltage is +13 above that of the source. When I continue and attatch the Mosfets I keep having one (atleast visable) of the R4-R7 burning up. I know I have to be driving the gates with to much current for this to happen, but even when I increase those resistors I get the same result, toast. Is there any way around this, or maybe I'm doing something else wrong. I've calculated the power for the resistor and it seems like it would be to much any way I go for a 1/4W but I see other H-bridges out there with what seems to be 1/4W resistors. If anyone can help me I would appreciate it. My project is due in 4 weeks and I'm stuck on this part of it. If there is any other information you need to help me just let me know.
Thank you,
Anthony
I woroking on my senior design for college and have a question about the H-bridge I've built. The set-up is similar to the one at this link:
http://www.parallax.com/dl/docs/cols/nv/vol2/col/nv52.pdf
Changes:
1) I have a +24V supply running to the top of the h-bridge instead of his power supply.
2) R1 and R2 are 100k resistors, not 120k
3) C3 and C4 are 0.033 uF (This is still 10 times the input capacitance of FET and should be fine)
4) D4-D7 are 13V zeners not 15V (Does not change much of anything)
5) R4-R7 I had set at 10ohm, and then 51ohm which lead me to my problem, btw these are 1/4W as well.
Problem:
I have the HIP4081A and surrounding circuitry running fine. I can use a scope to see the switching on the two Mosfets I need when the Fets are not attached. The gates voltage is +13 above that of the source. When I continue and attatch the Mosfets I keep having one (atleast visable) of the R4-R7 burning up. I know I have to be driving the gates with to much current for this to happen, but even when I increase those resistors I get the same result, toast. Is there any way around this, or maybe I'm doing something else wrong. I've calculated the power for the resistor and it seems like it would be to much any way I go for a 1/4W but I see other H-bridges out there with what seems to be 1/4W resistors. If anyone can help me I would appreciate it. My project is due in 4 weeks and I'm stuck on this part of it. If there is any other information you need to help me just let me know.
Thank you,
Anthony