Multi-Tech Systems MT2456SMI22 manual Pin Configurations, Pin Descriptions

Chapter 2 ￿ Mechanical Specifications

Pin Configurations

The MT2456SMI SocketModem with a serial interface use a 16-pin interface to provide an on-board DAA with tip and ring connections, audio circuit for call-progress monitoring and serial interface via logic level signals.

				Figure 2–2. Serial SocketModem Pins
Pin Descriptions
	Pin	Signal	I/O	Description
	#	Name	Type
	1	Tip	I/O	Tip Signal from Telco. Tip connection to the phone line (RJ11 Pin 3).
				SocketModem is Tip/Ring is polarity insensitive.
	2	Ring	I/O	Ring Signal from Telco. Ring connection to the phone line (RJ11 Pin 4).
				SocketModem is Tip/Ring is polarity insensitive.
	24	–RESET	I	Modem Reset (with weak pull-up). The active low –RESET input resets the
				SocketModem logic and returns the AT command set to the original factory
				default values or to "stored values" in NVRAM. –RESET is tied to VCC
				through a 250 ms time constant circuit for "Power-on-Reset" functionality. The
				modem is ready to accept commands within 6.5 seconds of power-on or reset.
				Reset must be asserted for a minimum of 300 ns.
	26	DGND		Ground.
29	DCDIND		DCD LED Indicator.
	30	RXIND		RXD LED Indicator.
31	DTRIND		DTR LED Indicator.
32	TXIND		TXD LED Indicator.
	33	–RTS	I	Request to Send. RTS signal is used for hardware flow control.
34	–RXD	O	Received Data. Used to send data received from the telephone line and also
				modem responses to the DTE. Modem response take priority over incoming
				data. When no data is transmitted, the signal is held in mark condition.
	35	–TXD	I	Transmit Data. The DTE uses this line to send data to the modem for
				transmission over the telephone line or to transmit commands to the modem.
				The DTE should hold this circuit in the mark state when no data is being
				transmitted or during intervals between characters.

Multi-Tech Systems, Inc. MT2456SMI-22 SocketModem Developer’s Guide 7