STMicroelectronics STA575

Overview

STA575 from STMicroelectronics is a mono-chip stereo Class-AB bridge power amplifier implementing BASH® architecture, delivering 80+80W into 4Ω/8Ω loads at 0.5% THD and 100+100W at 10% THD. It integrates dual-channel preamplifiers with programmable feedback compressors, precision rectifiers for digital converter tracking, on-off sequencing with mute/standby control, proportional over-power current limiting, absolute output current limit, thermal protection (130°C/150°C thresholds), and power supply overvoltage protection. Used in high-efficiency audio systems requiring dynamic headroom optimization.

For engineers reviewing the STA575 datasheet, STA575 pinout, STA575 application, or STA575 equivalent, key selection considerations include its BASH®-based adaptive rail tracking interface with STABP01, dual-channel compressor programmability (attack/release via external RC), ±23V bias supply range, FLEXIWATT27 27-pin thermally enhanced package, and integrated protection logic for speaker-safe turn-on/off and fault recovery.

Technical Context

The STA575 implements a two-stage signal path per channel: a fixed-gain (×5) preamplifier with externally programmable feedback-type compressor (threshold pin, Att_Rel1/2 pins), followed by an absolute-value rectifier generating TRK_1/TRK_2 signals for external digital converter voltage rail control. The output stage uses dual Class-AB bridges with differential gain of 12 dB and <0.5 dB channel mismatch.

Power protection is implemented via real-time instantaneous power sensing: voltage across sense resistor (CD+–CD+1) and V_DS are multiplied to generate I_PD, compared against 32W (regulation) and 60W (shutdown) thresholds. Thermal shutdown occurs at 150°C junction temperature, with mute activation at 130°C. Standby/mute/play states are controlled by precise voltage thresholds (0–0.8V / 1.6–2.5V / >4V) on pin 11.

Key Specifications

Pinout & Package

FLEXIWATT27 package: 27-pin thermally enhanced power package with exposed metal slug (pins 1 and 27 connected to –Vs), R_{th j-case} ≤ 1°C/W, rated for continuous operation up to 150°C junction temperature.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar stereo BASH®-compatible power amplifier applications.

Compared with STA575, STA559BW offers measurable THD and thermal margin improvements in a smaller package but sacrifices the FLEXIWATT27 thermal interface critical for convection-cooled legacy designs; TAS5630 achieves higher efficiency only at the cost of added subsystem complexity and loss of seamless STABP01 interoperability.

Availability

STA575 is available at Aetrix Electronics and suitable for home theater receivers, active studio monitors, powered subwoofers, and multi-zone audio distribution systems requiring stable component supply and long-term industrial availability.

Supply support for STA575 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in analog, power, and automotive ICs with strong focus on energy-efficient and system-integrated solutions.

The STA575 belongs to ST's BASH® audio power amplifier product line, designed specifically for high-fidelity, high-efficiency stereo amplification in space-constrained consumer and professional audio equipment where adaptive rail tracking reduces thermal load without sacrificing dynamic range.

FAQ

What is the required external digital processor for STA575 operation?

The STA575 must be used with the STABP01 digital processor to implement full BASH® functionality. The STA575 generates TRK_1/TRK_2 tracking signals and receives regulated CD+/CD– rails from STABP01. Without STABP01, the device operates as a fixed-rail Class-AB amplifier with reduced efficiency and no adaptive rail modulation capability.

How does the compressor threshold pin (pin 17) affect gain behavior?

Pin 17 accepts a DC voltage from –5 V to 0 V that sets the input amplitude threshold at which compression activates. At V_TH = –1 V, compression begins at ~2 V_pk input; at V_TH = –5 V, it begins at ~10 V_pk. The preamp gain drops from ×5 to 2·|V_TH|/V_in in compression region, capping output at ~2·|V_TH| peak to prevent clipping and excessive power dissipation.

Can STA575 drive 2Ω loads?

No. Absolute maximum output current is 7.7 A, and electrical characteristics are specified only for 4Ω and 8Ω loads. Driving 2Ω would exceed safe operating area limits under typical supply conditions (+28V/–23V), triggering immediate SOA protection shutdown. ST does not characterize or guarantee operation below 4Ω.

What is the purpose of pins 1 and 27 being tied to –Vs and the thermal slug?

Pins 1 and 27 provide low-impedance connection between the internal power transistor substrate and the exposed metal slug, enabling direct thermal conduction to the heatsink. This dual-pin configuration halves thermal resistance (R_{th j-case} ≤ 1°C/W), critical for dissipating up to 60W of transient power without exceeding 150°C junction temperature in convection-cooled designs.