STMicroelectronics TS821AILT

Overview

TS821AILT from STMicroelectronics is a 1.225V, ±1% precision micropower shunt voltage reference in SOT23-3 package, operating from 45μA to 12mA with 120ppm/°C tempco over -40°C to +85°C. It delivers stable reference voltage for low-current, space-constrained analog monitoring in battery-powered instrumentation and SMPS feedback loops.

For engineers reviewing the TS821AILT datasheet, TS821AILT pinout, TS821AILT application, or TS821AILT equivalent, key selection criteria include initial accuracy (±1%), ultra-low operating current (45μA max), temperature coefficient (120ppm/°C), static impedance (0.25–0.5Ω), and capacitive-load stability-critical for precision ADC biasing and isolated power supply sensing.

Technical Context

The TS821AILT functions as a two-terminal shunt reference, sinking current to maintain a precise 1.225V cathode-to-anode voltage. Its operation requires an external series resistor to set cathode current between 45μA and 12mA, with output regulation independent of input voltage above V_REF + I_KR_SERIES.

It achieves ±1% initial tolerance at 25°C and maintains stability across industrial temperature range via curvature-compensated bandgap design. Static impedance remains below 0.5Ω from 45μA to 1mA, enabling low-noise (<200nV/√Hz) performance in high-resolution measurement front-ends.

Key Specifications

Pinout & Package

SOT23-3L plastic micropackage (3.04mm × 2.64mm × 1.02mm), lead-free, ECOPACK® compliant, rated for 260°C soldering (10s).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt voltage reference applications.

Compared with TLVH431AIDBZR and MAX6008AEUR+T, the TS821AILT uniquely combines exact 1.225V output, ±1% tolerance, and 45μA max I_Q in SOT23-3-making it optimal for legacy designs requiring drop-in replacement of earlier TS821 variants and battery-life-critical 1.225V reference applications.

Availability

TS821AILT is available at Aetrix Electronics and suitable for battery chargers, portable instrumentation, and switch-mode power supplies requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for TS821AILT 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 microcontrollers, power ICs, sensors, and analog components for industrial, automotive, and consumer markets.

The TS821 series belongs to ST's precision analog reference product line, engineered specifically for low-power, high-stability voltage referencing in space-constrained and battery-operated systems.

FAQ

What is the minimum cathode current required for regulation at -40°C?

The TS821AILT requires a minimum cathode current of 50μA across the full -40°C to +85°C range to maintain regulation within specification. At 25°C, the minimum is 45μA, but derating to 50μA ensures guaranteed performance at temperature extremes per Table 4's "-40°C < Tamb < +85°C" row for Ik-min.

Can TS821AILT drive a 100µF capacitor directly without oscillation?

Yes-the datasheet explicitly states high stability with capacitive loads, and Figures 1–2 show stable operation with CL = 0µF, 10µF, and 100µF. No series isolation resistor is needed, simplifying layout in SMPS feedback networks where bulk capacitance is used for noise filtering.

How does the 120ppm/°C temperature coefficient translate to voltage drift over temperature?

Over the -40°C to +85°C range (125°C span), 120ppm/°C yields a worst-case drift of 125 × 120ppm = 15,000ppm = 1.5% of 1.225V = ±18.4mV. Combined with ±1% initial tolerance, total error remains within ±2.5%-verified by the ±22mV tolerance band in Table 4.

Is Pin 3 (NC) electrically isolated or thermally coupled to the die?

Pin 3 is internally unconnected (No Connect), but the SOT23-3L mechanical drawing shows it shares the same leadframe as Pin 1 (Anode). It is thermally coupled to the die via the package mold compound and leadframe, so grounding Pin 3 improves thermal stability and reduces temperature-induced drift in high-precision applications.