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Original question:

DLP4710EVM-LC: firmware for DLP4710LCFQL replace with DLP4710AFQL

DLP4710: P47 DMD2 high-voltage VOFS and VRST power-on and power-off waveforms are somewhat abnormal, affecting the DMD bright and dark spots

HUA ZHANG
Prodigy 40 points

Part Number: DLP4710

DMD chip model used: DLP4710AFQL.

Chip model that provides three high-voltage power supplies for the P47 DMD chip: TPS65150QPWPRQ1.

We have currently produced 200 projector units, and 12 of them have issues with bright and dark spots. Among these, 8 units are on the BBF line, and 4 units are not on the BBP line. We need to analyze the cause.

Currently, the timing measurements for DMD power-on and power-off meet the requirements, but there are some abnormalities in the DMD high voltage VOFS and VRST power-on and power-off waveforms. Could this cause bright and dark spots to appear on the DMD chip?

1. After powering the DMD high-voltage VOFS (10V) to 10V, there is a small segment of ripple, with the minimum measured voltage around 9.6V and a frequency of 10kHz. Could this cause the DMD chip to have bright and dark spot issues?

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2. When the DMD high-voltage VOFS (10V) power is turned off, there will be steps. Will this cause bright or dark spots on the DMD chip?

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3. When the DMD high-voltage VRST (-14V) is powered on and off, there will be a positive voltage overshoot, with a maximum positive voltage of about 0.36V. Could this cause bright or dark spot issues on the DMD chip?

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