ZHCSSR6B August 2023 – April 2024 THVD4431
PRODUCTION DATA
THVD4431 has 2 termination resistors of nominal 120 Ω, one across R1/R2 and another across R3/R4 in RS-485 mode. Both termination resistors are enabled or disabled using pins as described in Table 7-2. Both the termination resistors can be enabled or disabled independent of the state of driver or receiver. Termination is OFF in RS-232 loopback, RS-232 3T5R, RS-485 loopback, unpowered and thermal shutdown modes.
Signal state | Device mode | Function | Comments |
---|---|---|---|
TERM_TX = VIO | Full duplex mode | 120 Ω enabled between R1 and R2 | Termination between R1/R2 is disabled by default |
TERM_TX = GND or floating | Full duplex mode | 120 Ω disabled between R1 and R2 | |
TERM_RX = VIO | Full duplex mode | 120 Ω enabled between R3 and R4 | Termination between R3/R4 is disabled by default |
TERM_RX = GND or floating | Full duplex mode | 120 Ω disabled between R3 and R4 | |
TERM_RX = X, TERM_TX = VIO | Half duplex mode | 120 Ω enabled between R1 and R2 | In half duplex mode, TERM_RX is don't care and TERM_TX has higher priority |
TERM_RX = X, TERM_TX = GND | Half duplex mode | 120 Ω disabled between R1 and R2 |
The on-chip 120 Ω termination resistor is designed for minimum variation across temperature and across common mode voltage on bus pins. The termination block offers a resistive load to the bus, and does not alter the magnitude or phase of the bus signals from DC to 20Mbps signaling. See the typical characteristic curves for variation of termination resistor with voltage and temperature.