ZHCSSR6B August 2023 – April 2024 THVD4431
PRODUCTION DATA
In RS-232 mode, only way to disable driver is to go in shutdown mode by pulling SHDN pin low. A logic high at inputs for driver L3, L4 and L6 causes driver outputs R3, R4 and R6 to be driven low towards negative charge pump output V-. A logic low at inputs for driver L3, L4 and L6 causes driver outputs R3, R4 and R6 to be driven high towards positive charge pump output V+. If logic inputs are left floating due to the pull-up resistors on driver logic inputs, the driver outputs are driven low towards V-.
Table 7-6 is valid irrespective of the state of SLR pin.
| INPUT | ENABLE | OUTPUTS | FUNCTION |
|---|---|---|---|
| L3, L4, L6 | SHDN | R3, R4, R6 | |
| H | H | Low (driven towards V-) | Normal operation with inverting logic |
| L | H | H (Driven towards V+) | Normal operation with inverting logic |
| X | L | High impedance | TX and RX are disabled in shutdown mode |
| Open | H | Low (driven towards V-) | Since pull-up on logic input pin, output driven low by default |
For the RS-232 receiver, if the receiver bus inputs are above rising threshold VIT+, corresponding received logic output goes low. Also, if the receiver bus inputs are below falling threshold VIT-, corresponding received logic output goes high.
Table 7-7 is valid irrespective of the state of SLR pin.
| RS-232 BUS INPUT | LOGIC OUTPUT | FUNCTION |
|---|---|---|
| VIRx (voltage on R1, R2, R5, R7 or R8) | L1, L2, L5, L7, L8 | |
| VIT+ < VIRx | L | Normal operation with inverting logic |
| VIT- < VIRx < VIT+ | ? | Indeterminate bus state |
| VIRx < VIT- | H | Normal operation with inverting logic |
| X | High impedance for SHDN = GND | Receiver disabled in shutdown mode |
| Open-circuit bus | H | Fail-safe high output |