I see the scope shots but I do not see the circuit. That would be good to see because I am not sure how you could get such a high output voltage. Do you have extremely long, high resistance traces to the LEDs? It would be really nice to see the LED current…
Hi Derek,
Here is the design spreadsheet for LM3409HV :
4743.LM3409 Design Spreadsheet.xls
The LM3409 can do more than 5A since it is a controller as long as you select PFETs that are rated to handle that type of current.
Thanks,
Kevin
Hello,
Sounds like start-up delay. Are you using the EVM? I noticed in AN-2150 there is a soft start circuit that could cause what you are seeing, the values will cause a long delay, R20 = 499 Kohm and C12 = 47 uF on the EVM. There is a reason for…
To get 7-8A you will need a controller and not many that can do that level of current will run at 5V input. The TPS92640 and LM3409 would be able to do the current but you would need a higher input voltage. The TPS92691 could be configured as a buck regulator…
I haven't tried it on the bench, but it is a constant current buck converter, which means output current is continuous. You will need to switch the converter at a pretty high switching frequency for decent resolution, but you should be able to shunt FET…
Other Parts Discussed in Thread: LM3409HV , LM3409 , TPS92661-Q1 Hello, Please let me know about LM3409HV and TPS92661. (1) Roff and Coff setting Could you please let me know the setting method of Coff, Roff for wide Vout range ? Should we calculate the…
Hello Shafeeq,
It would be helpful to have both the PWM and SW node on the same oscilloscope picture.
Search for 'low noise ceramic capacitor' and a bunch of information will come up. As for the inductor, I've just tried different manufactures and…
Hi Joerg,
The TPS92515 is the successor to the LM3409. It was unreleased at the release of the TPS92661, but it would be a good choice for matrix systems. The inductance on the TPS92661 was chosen to limit ripple current with the very small currents…
Hello Jeff,
The LM3434 would be a direct drop in replacement, unfortunately I believe it is also in life buy status.
For replacing those devices we are recommending the TPS92640 or TPS92641. They have very good performance and only require a single…
Part Number: LM3409HVEVAL Other Parts Discussed in Thread: LM3409 , LM3409HV , TPS92515 I'm writing here trying to confirm that the behaviour I see is correct for this device.
In previous LED driver designs, I have employed an external MOSFET across…
