Chapter 3 – Electrical Characteristics
Wireless ModemModule MTMMC-G-F1 and MTMMC-G-F2 Developer’s Guide
20
Modem
Terminal
Level Shifter
Vcc
RI
DCD
RX
CTS
DSR
DTR
TX
RTS
Vcc
28
25
1
3
24
23
22
19
17
16
21
20
18
13
C1+
C1-
C2+
T1IN
T2IN
T3IN
T4IN
T5IN
R1OUTB
R2OUT
R3OUT
R4OUT
ON
C2-
T1OUT
T2OUT
T3OUT
T4OUT
T5OUT
R1IN
R2IN
R3IN
ERROR
OFF
27
2
26
4
5
6
7
10
12
8
9
11
15
14
S_RI
S_DCD
S_RX
S_CTS
S_DSR
S_DTR
S_TX
S_RTS
Vcc
Vcc
GND
Vcc
GND
MAX 3238
*This application note is valid for Vcc> 3.0 Volt (see MAX 3238 specifications)
Auto shut down mode is not used in this example.
Figure 3-3: Level Shifter Application Diagram for Serial Link
ON / ~OFF Interface
This input is used to switch ON or OFF the ModemModule. A high level signal has to be provided on the
ON/~OFF pin to switch on the modem. The level of the voltage of this signal has to be maintained to VCC during
a minimum time of 1 second. When powered off, the shutdown current is roughly 60 microAmperes.
Table 3-9: ON / OFF Pin Description
Signal
Pin Number
I/O
I/O Type*
Description
ON / ~OFF
15
I
CMOS
Module Power ON/OFF