FX614/MX614

– Bell 202 Compatible Modem

Telephony

FX614/MX614

– Bell 202 Compatible Modem

Product description

The FX614/MX614 is a low power CMOS integrated circuit for the reception or transmission of asynchronous 1200bps data, and is suitable for use in Bell 202 type systems. It is also capable of generating the 5bps or 150bps back channel.

The device incorporates an optional Tx and Rx data retiming function that removes the need for a UART in the associated µC when operating at 1200bps.

An optional line equaliser in incorporated into the receive path, this is controlled by an external logic level.

The FX614/MX614 may be used in a wide range of telephone systems. With a low operating voltage, a very low- current ‘sleep’ mode and an operating current of 1mA the device is ideal for portable, terminal and line powered applications. A 3.58MHz standard Xtal/Clock rate is required and the device operates from a 3.0V to 5.5V supply.

Devices are available through our Distributor Network.

Download Datasheet

Block diagram of the '604/'614/'654 chip family showing the receive filter, FSK demodulator, mode control logic, data re-timing and transmit filter stages

FX614/MX614

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FX/MX604 and FX/MX614 FAQ

Q. Can I use the FX614 in the same circuit as an MX614 or vice versa? The FX604 and MX604 V.23 modems are also pin and function compatable with each other.

A. Yes. The FX614 and the MX614 are completely pin and function compatible so code and hardware can be re-used in new designs. Similarly the FX604 and MX604 V.23 modems are also pin and function compatible with each other so are interchangeable.

604 – Why do the FX604 and FX614 apparently receive data when there is no input signal?

A. The FSK receiver of the FX604 and FX614 has a very high sensitivity and in the absence of a valid FSK signal will decode noise as data. This is not a fault but is due to the wideband properties of noise where sufficient energy may be present within the FSK decoder’s bandwidth.

604 – Are the FX614 and MX614 compatible with the HART specifications?

A. Yes they are, the FX614 and MX614 both appear to be suitable for encoding and decoding HART signals but have not been specifically designed to do so.

604 – Does CML offer a suitable replacement device for the TCM3105 (Bell202) modem application?

A. CML has several devices that can comply to the Bell202 specification: FX614 / CMX624 / CMX850 / CMX866 / CMX867A / CMX868A an B / CMX869A and B / CMX878.