Dear
At present, we use tps92512dgqt for LED driving design. The whole system shares about 30 groups of driving chips, each of which drives 16 lamps. When debugging the current output through 6-pin viadj, it is found that the consistency of the chips is poor, and about 7 groups can not realize small current regulation. The most abnormal one is that when the voltage of viadj changes from 0-1.8v, the output current is always about 100mA when the voltage changes from 0-0.6v (risense is 1 ohm), Current regulation can be realized after exceeding 0.6V. The current and voltage change proportionally. Three chips are tested. The other two abnormal chips have adjustable current above 60 or 80mA. Please help analyze the specific reasons. In addition, our chip manual says that the most accurate range is 180mv to 1.8V current output. When it is lower than 180mv, the current accuracy is poor, and there will be small current at 0V. To confirm the difference between the chips, Whether it can meet the target of accurately adjusting the current above 180mv. Because the project is urgent, I hope you can help deal with it as soon as possible. If you have any problems, you can communicate with me at any time. Thank you.
Supplement:
1. We have also done ABA verification here. The chip of the problem driving module is exchanged with the chip with normal adjustable current. The others remain unchanged. The problem follows the chip. It is preliminarily judged that it has nothing to do with the peripheral circuit.
Description of chip Manual:
At present, the circuit is as follows, and the DC input current is 27V:
Local PCB of single drive chip:
The output lamp board is 4 * 4 16 lamps connected in series. Refer to the following figure for details:
Thanks a lot.
