STMicroelectronics EVALTSM1052

Overview

EVALTSM1052 from STMicroelectronics is an evaluation board for the TSM1052 secondary-side constant voltage (CV) and constant current (CC) controller IC used in flyback-based battery chargers and AC/DC adapters. It supports dual-loop regulation with 1.21 V ±0.5% internal voltage reference, -200 mV current sense threshold, 1.7–18 V supply range, <300 µA quiescent current, and SOT23-6 package integration.

For engineers reviewing the EVALTSM1052 datasheet, EVALTSM1052 pinout, EVALTSM1052 application, or EVALTSM1052 equivalent, this board enables rapid validation of CV/CC loop stability, optocoupler feedback interface behavior, compensation network tuning, and low-voltage startup performance under real-world adapter load conditions.

Technical Context

The EVALTSM1052 implements a complete secondary-side feedback solution for isolated SMPS, integrating two transconductance op amps with OR-ed open-drain output to drive an optocoupler photodiode. One op amp regulates output voltage via a resistor divider connected to Vctrl; the other regulates output current using a sense resistor tied between Ictrl and Vsense.

It operates across -10 °C to +85 °C ambient, supports full compensation on both loops via accessible Vctrl/Vsense pins and OUT, and delivers precise dual-loop control without primary-side controller modification - enabling retrofit into existing flyback designs for improved CC accuracy and thermal margin.

Key Specifications

Availability

EVALTSM1052 is available at Aetrix Electronics and suitable for battery charger qualification, AC/DC adapter certification, and flyback converter design verification requiring stable component supply and documented reference implementation.

Supply support for EVALTSM1052 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, delivering silicon and system solutions for automotive, industrial, power, and consumer applications since 1987.

The TSM1052 product line targets cost-sensitive, space-constrained AC/DC power supplies - designed specifically to replace discrete TL431+op-amp feedback networks with a single-IC solution that improves CC accuracy and reduces bill-of-materials count.

FAQ

What is the primary function of the EVALTSM1052 evaluation board?

The EVALTSM1052 provides a fully assembled, tested reference design for the TSM1052 CV/CC controller, enabling engineers to validate secondary-side regulation performance in flyback converters. It includes all necessary passive components for voltage divider, current sensing, frequency compensation, and optocoupler interface - allowing immediate measurement of loop stability, cross-regulation, and transient response without custom PCB development.

Can EVALTSM1052 be used with non-ST primary-side controllers?

Yes - the EVALTSM1052 interfaces exclusively via optocoupler feedback and is agnostic to the primary-side PWM controller. It has been verified with common controllers including UC3842, UC3843, and VIPer series, and supports standard 1:1 CTR optocouplers such as PC817 and SFH615A. No firmware or configuration changes are required on the primary side.

Does the board support adjustable current limit without hardware modification?

No - the current limit is set by the external sense resistor value (e.g., 200 mΩ for 1 A), and the EVALTSM1052 ships with fixed resistors optimized for 5 V/1 A output. To change current limit, users must replace Rsense and optionally adjust RIC1/RIC2 compensation values per the TSM1052 datasheet equations - no jumpers or potentiometers are provided for field adjustment.

Is there documentation included with the EVALTSM1052 board?

Yes - the board ships with ST's UM0821 user manual, which includes schematic, bill-of-materials, layout guidelines, test procedures, and measured waveforms for voltage/current regulation, startup, and short-circuit recovery. All documentation is also publicly available on st.com under document number UM0821.