STMicroelectronics TSM1013AIST

Overview

TSM1013AIST from STMicroelectronics is a dual-loop constant voltage (CV) and constant current (CC) controller IC for secondary-side feedback in flyback SMPS, integrating a 2.5 V ±0.5% precision voltage reference, two transconductance op-amps, and current-sink output stages. It operates from 4.5 V to 28 V, supports 0–105°C ambient, and enables accurate adapter/battery charger regulation with only five external components.

For engineers reviewing the TSM1013AIST datasheet, TSM1013AIST pinout, TSM1013AIST application, or TSM1013AIST equivalent, key selection criteria include its dual-op-amp architecture with independent CV/CC loop compensation, 3.5 mA/mV transconductance gain, 200 mV low-level output voltage at 10 mA sink, ±0.5% reference accuracy, and SO-8 package compatibility with optocoupler-based isolation.

Technical Context

The TSM1013AIST implements two independent transconductance operational amplifiers: one configured as a non-inverting CV controller using internal 2.5 V reference and external resistor divider, the other as an inverting CC limiter sensing voltage across Rsense. Both op-amps feature accessible negative inputs and outputs for full external compensation via RC networks.

Its current-sink-only output stage combines CV Out (Pin 5) and CC Out (Pin 7) into a wired-OR configuration, ensuring immediate optocoupler activation when either voltage or current exceeds threshold-enabling robust overvoltage/overcurrent protection without additional logic.

Key Specifications

Pinout & Package

Package: SO-8 (Small Outline Integrated Circuit, 150 mil width), surface-mount, RoHS-compliant, thermal resistance R_thJA = 175 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant voltage and constant current control applications.

Compared with TL431ACDBVR and UCC3803D, the TSM1013AIST uniquely integrates both precision reference and dual transconductance op-amps in one SO-8 package-enabling true secondary-side CV/CC co-regulation with minimal external parts and no compromise on isolation integrity or loop stability.

Availability

TSM1013AIST is available at Aetrix Electronics and suitable for laptop adapters, USB-C PD chargers, smartphone fast chargers, and industrial battery maintenance systems requiring stable component supply across extended production lifecycles.

Supply support for TSM1013AIST 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 microcontrollers, power ICs, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The TSM1013AIST belongs to ST's dedicated SMPS secondary-side controller product line, engineered specifically for high-accuracy, low-component-count CV/CC regulation in isolated flyback converters used in energy-efficient power adapters and battery chargers.

FAQ

What is the maximum allowable supply voltage for TSM1013AIST?

The absolute maximum DC supply voltage (Vcc) is 28 V, enforced by an internal zener clamp. Operation above this level risks permanent damage. In practice, Vcc should be limited to ≤26 V under worst-case transient conditions to ensure margin, especially when derived from unregulated auxiliary windings.

Can TSM1013AIST drive an optocoupler directly without a series resistor?

No. A current-limiting resistor must be placed in series with the optocoupler LED between Cv Out or Cc Out and Vcc. With typical CTR ≥100% and 10 mA sink capability, a 1 kΩ resistor at 18 V yields ~10 mA LED current-ensuring reliable saturation while staying within 200 mV output voltage spec.

How does the TSM1013AIST achieve simultaneous CV and CC regulation?

It uses two independent transconductance op-amps whose current-sink outputs (Pins 5 and 7) are internally wired-OR'd. When either op-amp pulls current, the optocoupler activates-reducing primary duty cycle. This hardware OR ensures neither loop can override the other, enforcing strict "first-limit-wins" behavior essential for safety-critical charging.

Is external compensation mandatory for stable operation?

Yes. Both op-amps require external RC compensation networks connected between their negative inputs and outputs. The datasheet specifies 22 kΩ + 2.2 nF for each loop. Omitting compensation causes oscillation or sluggish response, particularly under light-load or dynamic-current conditions common in USB-C PD applications.