Dear Sir,
We used the LM3410 to drive four infrared lamps. Our current limit is around 0.19/0.36=527mA (Vin range:3.3V~4.2V).
When PWM is adjusted, the measured current is below 40% duty cycle as follows:
Duty cycle 10% current 8mA
20% current 11mA
30% current 85mA
40% current 115mA
50% current 652mA
......
100% current 2A
The duty cycle is suddenly increased from 40% to 50% to more than 500 mA. In addition, during the test of the camera, we turned on the infrared in night vision mode, and there will be streaks on the screen. It was later discovered that it was caused by the PWM-controlled IC. Now it is necessary to change the PWM to a duty cycle of 100%. This phenomenon will disappear. However, when the duty ratio is 100%, the current will reach 2A, which is unacceptable. Please help us to see what method is available to reduce the current. Thank you!
The spec range of the infrared lamp is 1.8V and the current is 1A.
Schematic:
