S50 Hardware User Guide
1VV0301505 Rev. 3
Page 19 of 60
2021-05-05
Not Subject to NDA
4.3.4.
Dynamic I/O Signal Type Changes Depending on UICP Status
To reduce current consumption when using UICP, the S50 FW supports the
following dynamic I/O signal type changes depending on the UICP activated resp.
deactivated status.
Signal
UICP deactivated
UICP activated
UART-CTS#
I-PD
I-FLOAT
IUR-IN#
I-DIS
I-FLOAT
IUR-OUT#
I-DIS
O-PP
(1)
I-PU: input pull-up; I-PD: input pull-down; I-FLOAT: input floating; I-DIS: input disconnected; O-PP: output push-pull
Table 3: Pin Assignments
Signal types I-PD, I-DIS, and O-PP may be left open. I-FLOAT must be driven to GND or
VCC to avoid open CMOS input oscillation.
If UICP is deactivated the pull-down resistor on UART-CTS# helps to keep the serial
interface active if UART-CTS# is open.
If UICP is active and the serial interface is down, UART-CTS# must be held at VCC and
thus the pull-down would cause an unwanted permanent current drain. Therefore, the
pull-down is switched off in this mode.
4.3.5.
UART Example Circuits
2
S50
GND
MAX3241
14
+3V3
22
23
2
3
7
8
4
6
1
9
TXD
RXD
RTS#
CTS#
IUR-OUT#
IUR-IN#
TXD
RXD
RTS
CTS
DTR
DSR
DCD
RI
RS232
DSUB9 (male)
DTE style connector pinout
9
4
10
5
11
6
7
8
19
13
18
12
17
16
15
F-4
D-2
D-7
F-3
B-4
D-5
UART_TXD
UART_RXD
UART_RTS#
UART_CTS#
IUR-OUT#
IUR-IN#
SHDN#
EN#
100n
100n
28
24
1
+3V3
100n 100n 100n
26
3
27
25
V+
VCC
V -
GND
C2+
C2-
C1+
C1-
220R
220R
220R
220R
220R
220R
5
SigGND
can be left open
VSUP
+3V3
Figure 9: S50 Serial Interface (RS-232 COM Port) Supporting UICP
