Multi-channel LED driver

cpfpost

Multi-channel LED driver [Copy link]

H5118.pdf (3.82 MB, downloads: 19)

2019-9-22 13:51 上传

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降压恒流LED驱动

Attached is the specification of the step-down constant current chip used to drive LEDs. I want to use this chip to drive multiple LEDs, such as four RGBW channels. I thought of a way to use four MOS tubes to cut the output, so that four outputs can be obtained. However, there is a problem with this method. The D pin of the chip is floating, that is, the voltage of LED- is uncertain, so the driving voltage Vgs of MOS is also uncertain. Moreover, this chip is a constant current, not a constant voltage, and MOS is a voltage-driven device, so this method does not work.

I have a project on hand now, which is a DCDC power supply design. It has a 3V input, a 24V output voltage, and a 6W bedside lamp. I have found many chips, but only this one is flicker-free. I originally thought of using a boost chip in the front and a buck constant current chip in the back, but as mentioned above, the solution does not work, so I would like to ask if you have any good ideas. Thank you all here.

qwqwqw2088

NXP has a chip that controls four-channel PWM. I don't know if it is in mass production yet.

PCA9633

Need microcontroller control

cpfpost

qwqwqw2088 posted on 2019-9-22 21:00 To control four-channel PWM, NXP has a chip. I don't know if it is in mass production. PCA9633 needs to be controlled by a single-chip microcomputer

I am in the power supply business and need to find a power chip or a good solution.

lzm2008

pay attention to.

伟林电源

Wouldn't it be simpler and less expensive to control with a single-chip microcomputer?

伟林电源

cpfpost posted on 2019-9-22 21:22 I am in the power supply business and need to find a power supply chip or a good solution

There should be very few four-channel PWM control chips. You can expand this idea a little bit. What about using a single-chip microcomputer?

lzm2008

Wouldn’t it be better to buy LED light strips with built-in LED Driver?

topwon

Four groups of RGBW LEDs are connected in series to the constant current source output. The cathode and anode of each group of LEDs are connected in parallel with a PMOS tube, S is connected to the anode, and D is connected to the cathode. When the control pin G is grounded, the MOS is turned on, and the corresponding LED light is off (short-circuited by the MOS tube). When the G control pins of all MOS tubes are low (to turn off all 4 color lights), the "line or" circuit outputs a low level to control the constant current source PWM pin to turn off the output.

topwon

This circuit is based on the design of Philips' 4-color bulb, which we have also verified in our own bulb products. The G level of each MOS tube can receive a PWM signal to adjust the brightness (that is, color) separately.