ADS7038: ADS7308, PARALLEL CONNECTION, COMMUNICATION, PCB PATTERN LENGTH

YoungSoo You

Prodigy 50 points

Part Number: ADS7038
Other Parts Discussed in Thread: TMS320F28335, ADS7830, , SN74LVC2G07

ADS7038IRTER IC is used for communication with DSP (TMS320F28335).

DSP uses SPI-A communication.

1) I am currently using 10 ADS7038IRTERs in parallel. Are there any problems that may occur?

2) Are pins 11 (CS), 12 (SDO), 13 (SCLK), and 14 (SDI) of the IC affected by PCB wiring or HARNESS WIRE length?

3) If I am affected, how should I resolve it? (EX. Additional parts, circuit modification, etc.)

over 1 year ago

0 Tom Hendrick over 1 year ago

TI__Guru**** 173756 points

Sounds interesting!

Especially since the TMS320F28335 only has one SPI interface. How are you managing 10 chip select inputs? Assuming SCLK and SDO are common to all devices, you should consider a driver between the TMS320 and the ADS7830. You can drive the SCLK and SDO into 2 buffers (each, 4 in total) and then fan out each to five ADS7038 devices. You can do the same for SDO back to the TMS320F28335. If the delay from SCLK out to SDO return approaches 1/2 of the SCLK period at the receive end, you will begin to get corrupted data on the MCU side.

0 YoungSoo You over 1 year ago in reply to Tom Hendrick

Prodigy 50 points

1) Chip select is connected to 28335 GPIO.

2) All ADS7830 devices are connected to the same line.

3) I currently have the SN74LVC2G07DBVR part. Is it possible to test with this part?

4) If testable, please provide a reference circuit or application.

0 Tom Hendrick over 1 year ago in reply to YoungSoo You

TI__Guru**** 173756 points

Your driver should be fine. I won't be able to test anything for you but we'd be happy to review your schematic and layout once you are ready.

0 YoungSoo You over 1 year ago in reply to Tom Hendrick

Prodigy 50 points

Thank you For Reply

- Two options are being considered.

- Tell us about the risks that may arise if you apply the two methods.

- Lastly, please review the circuit diagram.

1) Add BUFFER

2) Add Differential Line Drivers

0 Tom Hendrick over 1 year ago in reply to YoungSoo You

TI__Guru**** 173756 points

Can you use the Altium PDF output process? These screen shots are too blurry to do a complete review.

0 YoungSoo You over 1 year ago in reply to Tom Hendrick

Prodigy 50 points

Q_A.pdf

This is an Altium project PDF conversion file.

0 Tom Hendrick over 1 year ago in reply to YoungSoo You

TI__Guru**** 173756 points

How far do you expect the signals to travel? The LVDS devices are not connected correctly. You don't necessarily need to have an SN74LVC2G07 for each and every device. One driver fanned out to five ADC's would be appropriate.

Data converters

Data converters forum

ADS7038: ADS7308, PARALLEL CONNECTION, COMMUNICATION, PCB PATTERN LENGTH