STMicroelectronics TSM1013IST

Overview

TSM1013IST from STMicroelectronics is a dual-op-amp-based constant voltage (CV) and constant current (CC) controller IC for secondary-side feedback in isolated flyback adapters and battery chargers. It integrates a 2.5 V ±0.5% voltage reference, two transconductance op-amps (Gm = 3.5 mA/mV), and sink-only output stages. Designed for operation from 4.5 V to 28 V with 0–105°C temperature range, it enables precise regulation of both output voltage and charging current using external resistor networks and optocoupler feedback.

For engineers reviewing the TSM1013IST datasheet, TSM1013IST pinout, TSM1013IST application, or TSM1013IST equivalent, key selection criteria include its dual-loop CV/CC control architecture, internal 2.5 V reference precision, sink-output transconductance gain, SO-8 package thermal resistance (175 °C/W), and compatibility with standard optocoupler-based feedback topologies in AC/DC power supplies.

Technical Context

The TSM1013IST implements two independent transconductance amplifiers: one configured as a voltage controller (Cv−/Cv Out) and the other as a current limiter (Cc−/Cc+/Cc Out), sharing a common 2.5 V reference. Both op-amps feature fully accessible inputs and outputs for external compensation (e.g., Rcv1 = 22 kΩ + Cvc1 = 2.2 nF).

Its sink-only output stage provides ORing functionality - either CV or CC loop activation pulls the shared output low to drive the optocoupler LED, enabling automatic priority-based regulation without external logic. The internal zener clamp limits Vcc to 28 V, supporting direct connection to regulated secondary rails.

Key Specifications

Pinout & Package

Package: SO-8 (Small Outline Integrated Circuit, 150 mil width), surface-mount, RoHS-compliant.

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 TSM1013IST uniquely integrates both CV and CC analog control loops with a precision reference in one SO-8 package, enabling higher accuracy, smaller footprint, and true secondary-side regulation - critical for safety-certified and high-precision charging applications.

Availability

TSM1013IST is available at Aetrix Electronics and suitable for USB-C PD adapters, lithium-ion battery chargers, medical wall adapters, and industrial DC power supplies requiring stable component supply across long production lifecycles.

Supply support for TSM1013IST 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, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The TSM1013IST belongs to ST's dedicated power management analog controller product line, engineered specifically for high-accuracy, low-component-count secondary-side regulation in isolated AC/DC converters and battery charging systems.

FAQ

What is the maximum sink current capability of the TSM1013IST outputs?

The TSM1013IST provides a short-circuit sink current of 27–50 mA per output (Cv Out and Cc Out), sufficient to directly drive standard optocoupler LEDs such as PC817 or SFH615A without external transistors. This rating applies when sinking into Vcc, and the output voltage drop remains below 600 mV at 10 mA load, ensuring reliable LED turn-on across temperature and process variation.

Can the TSM1013IST operate with a supply voltage below 4.5 V?

No - the absolute minimum operating Vcc is 4.5 V per datasheet specifications. Below this voltage, internal reference startup and op-amp biasing are not guaranteed. During system start-up, if secondary rail voltage rises slowly, external auxiliary bias (e.g., from transformer auxiliary winding) may be required to ensure reliable TSM1013IST enablement before main output regulation begins.

How does the ORing function between Cv Out and Cc Out work electrically?

Both Cv Out and Cc Out are open-drain NMOS sink outputs tied together externally (typically at optocoupler LED anode). Whichever amplifier detects its threshold first pulls the shared node low, activating the optocoupler. No external diodes are needed because the outputs are designed for wired-OR operation - the lower impedance path dominates, enforcing natural priority without timing conflicts or shoot-through risk.

Is the 2.5 V reference usable as a standalone precision voltage source?

Yes - the Vref pin delivers up to 10 mA with ±0.5% initial accuracy (TSM1013A) and 20 mV total deviation over 0–105°C. It can serve as a stable reference for external ADCs, comparators, or DACs, provided load capacitance stays below 100 pF and output current remains within datasheet limits to avoid regulation error or thermal drift degradation.