Hi there,
We've been developing our own board for use with a DLP.
We've been developing our own board for use with a DLP.
This is our second revision, and currently our design exhibits a very loud buzzing noise which directly corresponds to the VLED rail and load applied. Here are some details:
- VINL (pins 1 and 2 of the DLPA2005) connected to stable 5V rail.
- With the projector OFF, the buzzing is not present.
- With the projector ON and LEDs connected, the buzzing is loud.
- With the projector ON and LEDs disconnected, the buzzing is present but not as loud.
- The input and output capacitance for the VLED circuit match TI's reference designs and previous prototypes (which did not have buzzing).
- The inductor value matches TI datasheet and reference designs.
- We have tried increasing input and output capacitance for the VLED circuit, and tried 2 different inductors - none of these had any effect at reducing the buzzing.
Is there anything else to check in hardware that we could have missed?
We suspect a stability issue with the VLED regulator, but there appears to be no provisions for tuning compensation.
For software, could enabling transient current limiting help?
If so, how can we access those registers, as our only interface is through I2C and TI proprietary firmware?
Many thanks in advance
