Specifications

Chapter 7 – SocketModem ISDN (MT128SMI)
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342C) 105
Electrical Characteristics
3.3 V and 5 V Serial SocketModem ISDN
3.3 V DC Characteristics (TA = 0°C to 70°C; VDD = 3.3 V ± 0.3 V) VDDMAX = 3.6 V
5 V DC Characteristics (TA = 0°C to 50°C; VDD = 5 V ± 0.25 V)
VDDMAX = 5.25 V
Inputs Input High Input Low
–DTR (40), –TXD (35), –RTS (33) Min 2.0 V Max 0.8 V
–RESET (24) Min 2.0 V Max 0.8 V
RX+, RX- (S/T Interface Receive) Min 90 mV Peak
Normal Mode
Min 220 mV Peak
Sleep Mode
Input Capacitance
15 pF
Outputs Output High Output Low Current Drive
–DCD (39), –CTS (38), –DSR (37)
–RI (36), –RXD (34), TCLK (11),
RCLK (12)
Min 4 V/ 2.4 V Max 0.5 V/0.5 V (5 V/3.3 V) 3.2 mA,
7.0 mA for TXD
TX+, TX- (S/T Interface Transmit) 1.17 V peak @
6 mA RL= 50 ohms
Application Notes
Safety Warning Telecom / ISDN-ST
This device is for connection to the ISDN S/T side of an ISDN NT1 device only.
Interface Connector Contact Assignments
Pole (contact) assignments for 8-pole connections (plugs and jacks; i.e., RJ-45)
Function I.430 Polarity Optional Polarity Pole Number
TE NT
3 Transmit Receive + +
4 Receive Transmit + –
5 Receive Transmit – +
6 Transmit Receive – –
ISDN Interface