User Manual Q&AAnswer
Dec 03, 2025 - 01:52 PM
To adjust the LED brightness using the EVAL-LT8374-AZ 60V Synchronous Step-Down LED Driver, you can utilize analog dimming or PWM dimming methods. Here's how you can implement these dimming techniques:
1. **Analog Dimming (Method 1):**
- **Procedure:** Apply a DC voltage between 0.25V and 1.25V to the CTRL pin to adjust the LED current level.
- **Implementation:** Connect a single resistor between the CTRL pin and GND to set the voltage. An internal 20μA current source is available for this purpose. Up to a 20:1 Analog Dimming ratio is recommended.
2. **Analog Dimming (Method 2):**
- **Procedure:** Apply an external PWM signal between 15kHz to 200kHz with a duty cycle ranging from 12.5% to 62.5% to the CTRL pin to adjust the LED current level.
- **Implementation:** Refer to the 'LED Current (Digital CTRL)' section in the LT8374 data sheet for the relationship between V(ISP-ISN) and the CTRL duty cycle. Up to a 20:1 Analog Dimming ratio is advised.
3. **PWM Dimming:**
- **Procedure:** Apply an external PWM signal below 10kHz with a variable duty cycle to the CTRL pin to control LED brightness by delivering current pulses to the LEDs.
- **Implementation:** Lower PWM dimming frequencies allow for higher achievable dimming ratios while maintaining output regulation. The EVAL-LT8374-AZ can achieve up to a 500:1 dimming ratio with a 100Hz PWM dimming signal.
By following these and procedures, you can effectively adjust the LED brightness using the EVAL-LT8374-AZ 60V Synchronous Step-Down LED Driver according to your requirements.
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