Time ± 2 Ps/div

5V

VCC

GND

D

DE

R

RE

B

A

RxD

TxD

DIR

MCU/

UART

10k

10k

TVS

R2

R1

100nF

100nF

19

THVD1500

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Typical Application (continued)

9.2.2 Detailed Design Procedure

In order to protect bus nodes against high-energy transients, the implementation of external transient protection

devices is necessary. Figure 22 suggest a protection circuit against 1 kV surge (IEC 61000-4-5) transients.

Table 3 shows the associated Bill of Materials.

Figure 22. Transient Protection Against ESD, EFT, and Surge Transients for Half-Duplex Devices

Table 3. Bill of Materials

DEVICE

FUNCTION

ORDER NUMBER

MANUFACTURER

XCVR

RS-485 transceiver

THVD1500

TI

R1

10-Ω, pulse-proof thick-film resistor

CRCW0603010RJNEAHP

Vishay

R2

TVS

Bidirectional 400-W transient suppressor

CDSOT23-SM712

Bourns

9.2.3 Application Curves

Data Rate = 300 Kbps

Figure 23. TBD

10 Power Supply Recommendations

To ensure reliable operation at all data rates and supply voltages, each supply should be decoupled with a 100

nF ceramic capacitor located as close to the supply pins as possible. This helps to reduce supply voltage ripple

present on the outputs of switched-mode power supplies and also helps to compensate for the resistance and

inductance of the PCB power planes.