JAJSOM1A April 2024 – April 2024 THVD4411
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 input for driver L2 causes driver output R3 to be driven low towards negative charge pump output V-. A logic low at input for driver L2 causes driver output R3 to be driven high towards positive charge pump output V+. If logic input is left floating due to the pull-up resistors on driver logic input, the driver output is driven low towards V-.
INPUT | ENABLE | OUTPUTS | FUNCTION |
---|---|---|---|
L2 | SHDN | R3 | |
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 |
Table 7-6 is valid irrespective of the state of SLR pin.
For RS-232 receiver, if receiver bus input is above rising threshold VIT+, then received logic output goes low. Also, if receiver bus input is below falling threshold VIT-, received logic output goes high.
RS-232 BUS INPUT | LOGIC OUTPUT | FUNCTION |
---|---|---|
VIRx (voltage on R2) | L1 | |
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 |
Table 7-7 is valid irrespective of the state of SLR pin.