PCB design problem.. MOSFET driver EL7104...

[danishkaleem]

hi..

i am using MOSFET driver ic EL7104 for the pulsed laser SPL LL85.

the circuit is giving proper response on the breadboard and the laser is emitting pulses.

but now once i made the PCB of the same circuit. the driver ic is not giving any response.
i have used the oscilloscope to check the response at various point. the pulse generator on the same pcb is producing pulses and these pulses are being fed to the driver ic. but the driver is not giving any output to the LASER.

does it has something to do with the impedance matching or inductive coupling on the PCB...
as the driver ic EL7104 maintains the integrity of pulse but increase the current.. so is it related to the thickness of tracks??
the most annoying thing is that if the same circuit is working good on breadboard.. then y not on PCB?? :!: :!:

pulses are of:
frequency: 2.4 Mhz
Width: 40ns
Voltage: 5V

Danish kaleem

 

[keith1200rs]

It sounds like a connection problem or blown driver IC.

Keith

 

[clayt]

A PCB will in general be a lot better than a breadboard setup, assuming you have done an okay job with the tracking and have the usual decoupling capacitors etc. That therefore points to a failed driver IC - unless you are seeing the same problem in multiple boards.
Replace the IC or build a second PCB (assuming you had more than one PCB made).

Clayton

 

[danishkaleem]

thanku 4 ur concern.. i have figured out the problem..
there was a diode which was not working.. i replaced it n it worked...