Silicon Laboratories ISOMODEM Si2401, Manual

Page: 9 / 74

Si2401
Preliminary Rev. 0.9 9
Figure 2. Asynchronous UART Serial Interface Timing Diagram
Table 6. Switching Characteristics
(V
D
= 3.0 to 3.6 V, T
A
= 0 to 70 °C for F-Grade )
Parameter Symbol Min Typ Max Unit
Baud Rate Accuracy –1 — 1 %
CTS
↓
Active to Start Bit
↓
t
csb
10 — — ns
RESET Pulse Width t
rl
1 — — ms
RESET
↑
to TXD
↓
t
rs
3 — — ms
Note: All timing is referenced to the 50% level of the waveform. Input test levels are V
IH
= 2.0 V, V
IL
= 0.8 V
Note: Baud rates (programmed through register SE0) are as follows: 300,1200, 2400, 9600, 19200,
38400, 115200, and 307200 Hz.
Receive Timing
Start
RXD
RXD
8-Bit Data
Mode (Default)
9-Bit Data
Mode
Stop D0 D1 D2 D3 D4 D5 D6 D7
Start Stop D0 D1 D2 D3 D4 D5 D6 D7 D8
t
csb
t
sbc
CTS
Transmit Timing
Start
Start
TXD
TXD
8-Bit Data
Mode (Default)
9-Bit Data
Mode
Stop
Stop D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7 D8
t
rl
RESET
t
rs
TXD