Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. CTLee123

    LM2409 Analog current dimming issue

    IRStuff - yes that's what we ended up doing after some deliberation (putting a 300Ohm resistor in parallel with the LED load). To avoid draining power when the LED is off but the voltage is still on, we will use a comparator to completely shut down the IC when we are near 0V for the IADJ pin...
  2. CTLee123

    LM2409 Analog current dimming issue

    Comcokid, I will take a look at the shunt regulator. Are you saying that the shunt regulator would provide a good abrupt transition that we could use to drive the EN pin? I think we need to turn off pretty close to 0V (since we still have usable light even AT 0V), so I will take a look at the...
  3. CTLee123

    LM2409 Analog current dimming issue

    We had considered PWM originally but it would have required an extra part and this is a commercial product so we were trying to keep the part count down. It would have been simpler in hindsight, but at the time we thought the analog and PWM controls would be able to dim equivalently. The idea...
  4. CTLee123

    LM2409 Analog current dimming issue

    Hello, On the LM3409 we are driving 4 series LEDs and are having difficulty getting the LEDs to dim far enough down using the IADJ pin (using the analog 0-1.24V control). At 0V, we still have about 13mA @ 10V flowing through the LEDs string and thus the LEDs are still lit. Looking more closely...

Part and Inventory Search

Back
Top