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THVD4431A: Review of Schematic for THVD4431A

Sri Krishna V

Prodigy 20 points

Part Number: THVD4431A

We are designing a product which provides RS232/422/485 which shall be software configurable based on THVD4431A.

Need to configure THVD4431A for RS485 Half and Full duplex, RS-422, and RS-232 with RTS,CTS.

Can you review the schematic

0 Ethan Sempsrott 1 month ago

TI__Mastermind 26602 points

Hi Sri,

Thanks for reaching out on E2E.

I'm reviewing this schematic, and I'll get back to you tomorrow.

-Ethan

0 Ethan Sempsrott 1 month ago in reply to Ethan Sempsrott

TI__Mastermind 26602 points

Hi Sri,

Here are my comments:

Pin 18 is a NC, and pin 17 is the only termination pin.
Ensure all capacitors are placed as close to the transceiver as possible and on the same layer.
Add a pulldown resistor to GND for L6. While in RS-232 mode, this prevents the TX input from floating and drawing more current.

Best,

Ethan

0 Sri Krishna V 1 month ago in reply to Ethan Sempsrott

Prodigy 20 points

Is pull down to GND also required for R5 or can i short R5 and R6 after grounding L6.

I see that pin 18 is TERM_RX and pin 17 is TERM_TX for THVD4431A. The circuit was designed for accommodating either of the chips.

Is there a problem in driving pin 18 as it is an NC.

in full duplex mode on THVD4431A dos pull up/down provide termination on both RX and TX channels (RX,TX,X,Y,A,B)

+1 Ethan Sempsrott 1 month ago in reply to Sri Krishna V

TI__Mastermind 26602 points

R5 can be left open as it has an internal pulldown resistor. Only L6 needs to be worried about as it is the only one without a biasing resistor.

No concerns with driving pin 18 since it is NC.

0 Sri Krishna V 1 month ago in reply to Ethan Sempsrott

Prodigy 20 points

Thank you.

I am posting my final schematic in case any one need it for reference.