TS421ID

Overview

The TS421ID is a monaural audio power amplifier manufactured by STMicroelectronics, designed to drive 16 or 32-ohm earpieces or receiver speakers in BTL mode. It operates from a supply voltage of 2V to 5.5V and delivers up to 367mW into a 16-ohm load at 5V with 10% THD+N. The device features an active-low standby mode that reduces supply current to 10nA typical. Key electrical parameters include a maximum supply current of 2.5mA, a signal-to-noise ratio of 95dB(A) at 5V, and a power supply rejection ratio of 56dB typical at 1kHz.

Feature Summary

• Eliminates bulky output capacitors through bridge-tied load (BTL) configuration
• Externally controlled standby mode significantly reduces supply current consumption
• Integrated circuitry for reducing ON/OFF click noise during operation
• Built-in short-circuit limitation for enhanced protection

Applications

• Driving 16 or 32 ohms earpiece or receiver speakers
• Mobile and cordless phones (analog / digital)
• PDAs & computers
• Portable appliances

Procurement Notes

Verify the specific ordering suffix against the manufacturer's documentation to confirm package type and gain configuration. The 'I' suffix indicates external gain setting capability, while other variants may offer fixed gains. Confirm availability status as this component series may be discontinued or subject to lifecycle changes. Ensure the selected variant matches the required standby logic level and thermal requirements for the target application.

Selection Notes

Select the TS421ID when a single-channel amplifier with low quiescent current and high efficiency is required. This part is suitable for battery-powered devices due to its wide operating voltage range and standby capabilities. Consider the external gain-setting resistors for flexibility in system design. Evaluate thermal dissipation characteristics based on the SO8 package and expected ambient temperature conditions.

Part Context

The TS421ID belongs to the TS419/TS421 family of mono audio amplifiers from STMicroelectronics. These components are engineered for portable electronics where space and power efficiency are critical. The family shares core architectural features but differs in standby logic polarity and packaging options. The TS421 specifically utilizes an active-low standby control signal.

Replacement Considerations

Public confirmed substitute part numbers: LM4889MA/NOPB, LM4889MAX/NOPB.