AnsweredAssumed Answered

ADV7391: Damaged Chip or Design Issue?

Question asked by bytejammer on Oct 11, 2012
Latest reply on Oct 18, 2012 by bytejammer

I have a video encoding design based on the ADV7390/1 and I'm troubleshooting an issue with my first prototype. The design is based on the Typical Applications Circuit shown in Figure 93 of the datasheet with VDD_IO, PVDD, and VDD powered at 1.8VDC and VAA powered at 2.7VDC. All the non-analog grounds (DGND, GND_IO, PGND) are tied together and connected to analog ground (AGND) through a ferrite bead. When powered the core supply input (VDD) is pulling a relatively large amount of current. Based on the voltage drop (1.8V drops to 1.6V) across the ferrite bead inline with the VDD 1.8V supply, it is pulling up to 0.5A. (The chip is getting very hot: enough to heat up the PCB through the pad underneath the chip.) All the other voltage inputs (VDD_IO, PVDD, VAA) appear to be okay, i.e. there's no voltage drop across their inline ferrite bead. The pixel input lines are tied to ground, HSYNC/VSYNC and the I2C bus lines are pulled to 1.8V. I've held RESET low and it doesn't make any difference in the power draw of VDD. I have not gotten to the point of setting chip registers via the I2C bus so the chip is operating in its default power up state.

 

Since I haven't gotten to point of data comms with the chip I'm wondering:

 

Is this amount of current draw to be expected prior to chip initialization or is the chip most likely damaged?

 

Thanks.

Outcomes