STMicroelectronics ALTAIR05T-800

Overview

ALTAIR05T-800 from STMicroelectronics is an off-line all-primary sensing quasi-resonant flyback switching regulator IC integrating an 800 V avalanche-rugged power MOSFET and a low-voltage PWM controller in a single SO16N package. It delivers constant voltage (CV) and constant current (CC) regulation without optocoupler, achieves ≤±5% load transient CV/CC accuracy, and supports 85–265 VAC input for mobile phone chargers.

For engineers reviewing the ALTAIR05T-800 datasheet, ALTAIR05T-800 pinout, ALTAIR05T-800 application, or ALTAIR05T-800 equivalent, key selection criteria include primary-sensing CV/CC regulation capability, 800 V drain breakdown rating, ZCD/FB-based demagnetization detection, cable drop compensation (CDC), and self-supply operation during CC mode under low auxiliary winding voltage.

Technical Context

The ALTAIR05T-800 implements a current-mode quasi-resonant flyback controller with integrated 800 V/1 A power section. Its ZCD/FB pin serves dual functions: transformer demagnetization detection for valley-switching turn-on and input voltage feedforward sampling for mains-independent CC regulation - both enabled by internal clamping (−60 mV to 3.3 V) and arming logic (100 mV threshold).

It operates across three adaptive modes: QR mode up to 166 kHz at heavy load, valley-skipping at medium/light load, and controlled burst-mode down to ~300 Hz at no-load. Protection includes hiccup-mode OCP (1 V CS threshold), brownout detection, and auto-restart on auxiliary disconnection or secondary short - all implemented without external components beyond R_CS, R_FF, and CDC resistor.

Key Specifications

Pinout & Package

ALTAIR05T-800 uses SO16N package (10.3 × 10.3 mm, 1.75 mm height), with exposed drain pads (pins 13–16) thermally connected to internal metal frame for enhanced heat dissipation. The copper area under drain pins must be designed per layout guidelines for R_{th j-pin} = 10 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar off-line quasi-resonant flyback controller applications.

Compared with ICE5QSAG and LNK364PG, ALTAIR05T-800 uniquely integrates 800 V ruggedness, all-primary CV/CC, and cable compensation - enabling single-chip, optocoupler-free 5–20 W chargers meeting strict energy efficiency and output accuracy requirements.

Availability

ALTAIR05T-800 is available at Aetrix Electronics and suitable for smartphone fast charging adapters, USB-C wall chargers, and compact IoT power supplies requiring stable component supply, long-term lifecycle support, and compliance with global energy standards.

Supply support for ALTAIR05T-800 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 ALTAIR series targets high-efficiency, low-BOM-count AC-DC converters for portable and universal chargers - emphasizing primary-side regulation, integrated high-voltage switches, and adaptive multi-mode control to meet evolving energy regulations.

FAQ

What is the purpose of the ZCD/FB pin's dual functionality?

The ZCD/FB pin detects transformer demagnetization (via negative-going edge at ~60 mV) to enable valley-switching turn-on, while simultaneously sourcing current proportional to input voltage for feedforward-based CC regulation. Its internal clamps (−60 mV to 3.3 V) and arming logic prevent false triggering from leakage spikes, ensuring reliable QR operation across 85–265 VAC input.

How does the ALTAIR05T-800 achieve self-supply during constant-current regulation?

During CC mode, auxiliary winding voltage may fall below V_CC UVLO. The internal HV start-up generator activates whenever V_CC drops below 10.5 V, drawing ~5.5 mA from the DRAIN pin to recharge the V_CC capacitor. This ensures uninterrupted operation without auxiliary winding redesign - a key advantage over controllers requiring dedicated bias windings.

Can the CDC function compensate for variable cable resistance in USB-C applications?

Yes - the CDC pin sinks current linearly with output load current, raising the CV setpoint via an external resistor to ZCD/FB. When properly calibrated (e.g., 100 µA/mA load), it offsets voltage drop across cables up to 0.8 Ω, achieving ≤±1% regulation at the USB-C receptacle - verified in ST's AN4723 reference design for 5 V/3 A adapters.

What protection features are implemented without external components?

The ALTAIR05T-800 integrates hiccup-mode OCP (triggered at 1 V on SOURCE), auxiliary winding disconnection detection (via ZCD/FB current loss), and secondary rectifier short detection (via abnormal ZCD timing). All protections auto-restart after V_CC falls below 5 V - requiring no external timers, latches, or sense resistors beyond the standard R_CS.