STMicroelectronics TSM1011AIST

Overview

TSM1011AIST from STMicroelectronics is a dual-loop CV/CC controller IC for secondary-side regulation in flyback adapters and battery chargers, featuring 0.5% precision 2.545 V reference, two transconductance op-amps with ORed sink outputs, and operation from 4.5 V to 28 V supply. It enables accurate voltage and current limiting via external resistor networks and optocoupler feedback.

For engineers reviewing the TSM1011AIST datasheet, TSM1011AIST pinout, TSM1011AIST application, or TSM1011AIST equivalent, key selection criteria include reference voltage tolerance (0.5%), input offset voltage (0.5 mV typ), sink output capability (50 mA short-circuit current), and SO-8 package compatibility with standard adapter PCB layouts.

Technical Context

The TSM1011AIST integrates two independent transconductance operational amplifiers whose outputs are wired in common-collector (OR) configuration to drive an optocoupler LED. One amplifier implements voltage control using a resistive divider referenced to the internal 2.545 V bandgap, while the other implements current control using a sense resistor and a VRef-derived threshold network.

Both amplifiers support full external compensation via accessible inverting inputs and outputs; typical networks use 22 kΩ + 2.2 nF series RC elements. The device includes an internal 28 V Zener clamp on VCC and 2 kV HBM ESD protection on all pins, enabling robust operation in cost-sensitive AC/DC adapter environments.

Key Specifications

Pinout & Package

Package: SO-8 (Small Outline, 150 mil width), RoHS-compliant ECOPACK® variant, thermal resistance R_thJA = 175 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar CV/CC controller applications.

Compared with TL431+LM358, TSM1011AIST reduces component count by 60% and improves reference accuracy 4×; versus TSM1011ID, it delivers twice the voltage regulation precision at identical footprint and thermal performance.

Availability

TSM1011AIST is available at Aetrix Electronics and suitable for USB-C PD adapters, lithium-ion battery chargers, and industrial AC/DC power supplies requiring stable component supply with guaranteed long-term availability and consistent parametric performance.

Supply support for TSM1011AIST 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, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for automotive, industrial, and consumer markets.

The TSM1011 product line targets cost-sensitive, high-volume AC/DC adapter and battery charger applications requiring integrated, precision analog feedback without digital complexity or firmware overhead.

FAQ

What is the maximum allowable voltage on the VCC pin?

The absolute maximum rating for VCC is 28 V, enforced by an internal Zener clamp. Exceeding this voltage risks permanent damage. In practice, auxiliary supplies derived from transformer windings must be designed to stay within this limit-common approaches include series resistors or zener diodes before VCC. The clamp activates above ~28 V, dissipating excess energy as heat.

Can TSM1011AIST regulate both voltage and current simultaneously?

Yes-the two transconductance op-amps operate independently but share a common sink output (OUT pin). When either CV or CC loop demands increased optocoupler current, the OUT pin sinks more current, pulling the primary-side PWM duty cycle down. This OR logic ensures that the stricter of the two limits (voltage or current) always governs regulation without external arbitration.

How does the 0.5% reference tolerance impact output voltage accuracy?

With a typical 4.1 V output design using a 2.545 V reference and resistor divider, the 0.5% reference tolerance contributes ±20.5 mV error-less than half the total ±50 mV budget allowed for ±1.2% output accuracy. Combined with op-amp offset (0.5 mV) and resistor tolerances, it enables production-ready designs meeting stringent USB PD and medical charger specifications.

Is external compensation mandatory for stable operation?

Yes-both op-amps require external compensation for closed-loop stability. The datasheet provides recommended values (22 kΩ + 2.2 nF) for each loop, connected between OUT and the respective inverting input (CV− or CC−). Omitting compensation causes oscillation or sluggish response; values may be adjusted based on transformer leakage inductance and optocoupler CTR variation in final layout.