AS2524

Overview

The AS2524 is a CMOS integrated circuit designed for enhanced handsfree feature phones with CallerID and extended displays. It incorporates DC and AC line adaptation, speech circuits with softclipping, and loudspeaker amplification for handset and handsfree operation. The device interfaces with standard diallers via a parallel interface controlled by xPD, xMUTE, and HFI pins. Operating currents range from 15mA to 100mA in normal mode, reducing to 5mA with reduced performance. Key electrical parameters include a transmit gain of +37dB (handset) or +46dB (handsfree), receive gains of +7.5dB (RO) and +34dB (LO), and an operating voltage at the LI pin of 4.5V.

Feature Summary

• Integrated speech circuit with dual softclipping for acoustic shock prevention
• Parallel interface control for handset, handsfree, tone, and power-down modes
• Built-in voice switching attenuators to prevent acoustic coupling
• Loudspeaker amplifier output for handsfree and loudhearing applications

Applications

• Enhanced handsfree feature phones
• Devices with CallerID functionality
• Telephones with extended displays

Procurement Notes

Verify the specific revision level and package type when sourcing. Confirm that the parallel interface requirements align with the target dialler design. Ensure external components for impedance synthesis and side-tone balancing match the datasheet specifications. Check for availability as the component may be subject to end-of-life status.

Selection Notes

Select the AS2524 when a parallel interface is preferred over serial control. This model lacks programmable Tx/Rx gain and Line Loss Compensation found in the AS2523 variant. It is suitable for designs using common Taiwanese diallers where fixed gain settings are acceptable. Consider the AS2524B if permanent Line Loss Compensation is required.

Part Context

The AS2524 shares the same silicon die as the AS2523 and AS2524B. The primary distinction lies in the control interface; the AS2524 utilizes a parallel interface driven by hardware pins, whereas the AS2523 uses a serial interface. This allows the AS2524 to operate without a CPU, relying instead on standard dialler logic for mode selection.

Replacement Considerations

The AS2524B serves as a functional substitute if Line Loss Compensation is needed, as it permanently activates LLC high. The AS2523 offers equivalent audio performance but requires a serial interface and CPU control. Direct pin-to-pin replacement is possible only if the system supports the respective interface protocol.