AS2522B Analog Telephone IC
Telephone Line Interface and Speaker Phone Circuit
Description
AS2522 is a flexible CMOS integrated circuit that incorporates DC and AC line adaptation (DC-mask and synthesized AC-impedance of 100^) as well as a speech circuit with softclipping, line loss compensation and Rx volume control for handset and handsfree operation. It shall act as an a/b-line powered device, which is controlled by a CPU via a serial interface. Furthermore the AS2522 incorporates a DTMF, FSK transmitter, single tone and ringer tone generator.
AS2522 allows to use an off-the-shelf microprocessor without special blocks and functions for telephone applications. DTMF, FSK transmitter, single tone and ringer tone generator can be controlled via the serial interface as well as the gain settings in handset and handsfree mode.
Key Features
- Line/Speech circuit, DTMF dialer, FSK transmitter and tone ringereh on a 32-pin CMOS-IC
- Enhanced voice switching
- Background noise monitoring
- DTMF tone generator
- FSK Transmitter V.23, BELL202, V.21, BELL 103
- Ringer tone programmable
- Tx and Rx gain programmable
- Digital volume control of Rx signals
- DC characteristic programmable
- Dual softclipping in handset mode
- Tx-softclipping in handsfree mode
- Common monitor amplifier for loudhearing, handsfree and ringing
- Supply voltage generation for external circuitry
- Automatic line loss compensation (LLC)
- Real and complex impedance selectable by external components
- Side tone adaptation selectable by external components
- Unique EMC performance
- Operating range from 15mA to 100mA (down to 5mA with reduced performance)
- Few external components
- Package
- Available in 32-pin TQFP
Applications
The device is ideal for enhanced handsfree feature phones with CallerID and extended displays.
Block diagram for AS2522B Analog Telephone IC
AS2522B Telephone Line Interface and Speakerphone Circuit Block Diagram