STMicroelectronics TS4985EIJT

Overview

TS4985EIJT from STMicroelectronics is a dual-channel 1.2W stereo Class-AB audio power amplifier in flip-chip BTL configuration, operating from 2.2V to 5.5V supply, delivering 1.2W per channel into 8Ω at 5V/1% THD+N, with 10nA standby current and 106dB(A) SNR - deployed in portable LCD monitors and mobile handsets for compact, low-noise audio playback.

For engineers reviewing the TS4985EIJT datasheet, TS4985EIJT pinout, TS4985EIJT application, or TS4985EIJT equivalent, key selection criteria include BTL output architecture, dedicated left/right standby pins (STDBYL/STDBYR), thermal shutdown protection, external gain-setting resistors, and flip-chip thermal resistance of 110°C/W on 4-layer PCB.

Technical Context

The TS4985EIJT implements two independent BTL amplifiers, each with fully differential input stage and rail-to-rail output swing, enabling 2× output voltage swing versus single-ended topology and quadrupling output power at same supply voltage. Gain is externally programmable via R_IN/R_FEED resistor pairs, supporting closed-loop gains of −1, −2, or −10 depending on configuration.

It features dual independent standby control (STDBYL/STDBYR), where grounding either pin reduces its channel's quiescent current to ≤10nA while preserving fast wake-up time (90–130ms with 1µF bypass capacitor). Internal thermal shutdown activates at 150°C junction temperature, and PSRR reaches 62dB at 217Hz with grounded inputs.

Key Specifications

Pinout & Package

TS4985EIJT uses a lead-free 15-bump flip-chip package (no leads, no wire bonds), optimized for low thermal resistance (110°C/W on 4-layer PCB) and minimal board area. The die is mounted face-down with solder bumps directly contacting PCB pads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar stereo BTL audio amplifier applications.

Compared with TPA2013D1RTJR and MAX9718ETA+, TS4985EIJT uniquely offers per-channel 10nA standby, true BTL flexibility with external gain resistors, and optimal thermal performance in ultra-thin layouts - making it ideal for space-constrained, battery-sensitive dual-audio-path designs.

Availability

TS4985EIJT is available at Aetrix Electronics and suitable for cellular mobile phones, notebook computers, LCD monitors, and portable audio devices requiring stable component supply across extended production lifecycles.

Supply support for TS4985EIJT 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, designing and manufacturing analog, mixed-signal, power, and microcontroller solutions for industrial, automotive, and consumer markets.

The TS4985 belongs to ST's high-efficiency audio power amplifier product line, engineered specifically for low-voltage portable electronics demanding high SNR, ultra-low standby power, and minimal PCB footprint.

FAQ

What is the recommended bypass capacitor value for the BYPASS pin?

A 1µF ceramic capacitor must be placed between BYPASS pin and GND to establish a stable half-supply reference voltage for the BTL output stage. This capacitor ensures proper DC biasing and minimizes pop/click during startup and standby transitions. Use X7R or better dielectric with ≤100mΩ ESR; placement within 2mm of the pin is critical for stability.

Can TS4985EIJT drive 4Ω loads?

Yes - the device supports loads ≥4Ω per channel. At 5V supply, it delivers ~1.8W into 4Ω at 1% THD+N (per datasheet Figure 27). Power dissipation increases significantly, so thermal design must account for R_THJA = 110°C/W and ensure junction temperature stays below 150°C. Derating curves in Figure 60 must be consulted for continuous operation.

How does the STDBYL/STDBYR pin logic work?

Each standby pin is active-low: tying STDBYL or STDBYR to GND places its respective channel into ultra-low-power mode (I_STANDBY ≤10nA). Pulling the pin to ≥1.35V (but ≤V_CC) enables normal operation. The pin has hysteresis - V_STDBL = 0.4V max, V_STDBH = 1.3V min - preventing chatter near threshold. No external pull-up is required.

Is external compensation required for stability?

No external compensation is needed for standard configurations. The amplifier is unity-gain stable with capacitive loads up to 500pF (per GBP and phase margin specs). If larger capacitive loads (>500pF) or long traces are used, a small series resistor (1–5Ω) at each VO+ and VO− output is recommended to isolate capacitance and maintain ≥65° phase margin.