Hi
I am developing a DP to VGA converter on one of our carrier boards using the PTN3392.
Upon power up nothing seemed to be happening.
When checking the voltages I have found that pin 38 LDOCAP_AUX is sitting at 0.8V not 1.8V.
Pin 30 LDOCAP_CORE is at 1.8V as expected.
Can you have a look at the attached schematic and let me know what I am doing wrong.
Hi Mark Jeffrey,
please refer to the schematic attached. Your schematic seems to be not complete. I don't see pull-up resistors on the SDA and SCL I2C lines and there is also missing the part with the DP connector. Could you please also provide the missing parts of the schematic for review?
With Best Regards,
Jozef
Hi Josef
Have you had a cahnc to look at the schematic?
Hi Mark Jeffrey,
I have contacted an application engineer for the schematic review. For his answer please see below. Please answer the application engineer questions.
DESCRIPTION
Customer’s schematics looks OK, please check with customer for questions below.
With Best Regards,
Jozef
Hi Jozef
VDDA pin 37 is at 3.3V
HPD is at 0V
We have built 2 prototypes and both are seeing this issue.
Hi Josef
Probing the chip I noticed the JTAG pins didnt look as expected.
I cut the track on pin 5 TCK and the device sprang into life.
Measuring pin 5 at the device the voltage is 3.3V as this is an input I would have expected this to be floating.
Is there an issue with the JTAG interface on this device.
Hi Mark Jeffrey,
please see below an answer from the application engineer.
DESCRIPTION
Where the TCK pin is connected to in customer’s application board originally?
JTAG is only used for programming firmware into internal embedded MCU resided in the PTN3392 in factory ATE test stage, it should not be used in customer’s application.
With Best Regards,
Jozef
Hi Josef
TCK is connected to 3 other devices with JTAG interfaces as per the JTAG specification.
Hi Mark Jeffrey,
please see below an answer from the application engineer.
DESCRIPTION
PTN3392 JTAG interface is only used for ATE test in NXP production line, please ask customer to not connect PTN3392 JTAG pins to the other devices or system JTAG interface.
It will cause application issues if PTN3392 receives random clock/data from its JTAG interface.
We don’t provide command/protocol for PTN3392 JTAG interface, so that customer would not be able to send appropriate commands
to PTN3392 through JTAG interface.
With Best Regards,
Jozef