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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > AC DC Converters, Offline Switches

STMicroelectronics ALTAIR04-900

Name: ALTAIR04-900
Brand: STMicroelectronics
SKU: ALTAIR04-900
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: ALTAIR04-900

Manufacturer:: STMicroelectronics

Category:: AC DC Converters, Offline Switches

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: ALTAIR04-900.pdf

Description:: IC OFFLINE SWITCH FLYBACK 16SO

Quantity:: RFQ Add To RFQ list

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Product details

Overview

ALTAIR04-900 from STMicroelectronics is a high-voltage, all-primary-sensing quasi-resonant flyback controller with integrated 900 V avalanche-rugged power MOSFET, designed for off-line AC-DC conversion without optocoupler or secondary-side sensing. It delivers primary-side constant voltage (CV) and adjustable constant current (CC) regulation, supports 166 kHz max switching frequency, features valley-skipping and burst-mode operation, and targets auxiliary supplies in industrial 3-phase systems.

For engineers reviewing the ALTAIR04-900 datasheet, ALTAIR04-900 pinout, ALTAIR04-900 application, or ALTAIR04-900 equivalent, this device offers mains-independent CC limiting, low standby consumption (<1.4 mA quiescent current), UVLO protection, hiccup-mode OCP, and SO16N-packaged integration of PWM controller + 900 V power switch - critical for energy metering SMPS and robust industrial auxiliary supplies.

Technical Context

The ALTAIR04-900 implements current-mode control with transformer demagnetization detection via ZCD/FB pin to enable quasi-resonant valley switching, reducing EMI and turn-on losses. Its internal 900 V power section operates with R_DS(on) = 16 Ω (T_j = 25 °C) and supports single-pulse avalanche energy up to 25 mJ.

It integrates a high-voltage start-up generator sourcing 5.5 mA typical into Vcc, enabling direct bulk-capacitor powering - essential during CC regulation when auxiliary winding voltage drops below UVLO. The transconductance error amplifier (g_m = 2.2 mS typ.) and 2.5 V reference provide precise CV regulation using sampled-and-held ZCD/FB voltage at demagnetization end.

Key Specifications

Parameter	Value and Actual Design Meaning
V(BR)DSS	900 V min. - Enables direct operation from 3-phase rectified mains (up to ~800 V DC) with margin for surge and ringing.
R_DS(on)	16 Ω typ. @ 25 °C - Defines conduction loss and thermal dissipation in primary-side switch; impacts efficiency at medium-to-heavy load.
f_sw max	166 kHz - Top-limited switching frequency prevents excessive EMI and gate-drive losses at light load/high line.
I_q	1.4 mA typ. @ 50 kHz - Low operating supply current enables <300 mW no-load input power, supporting Energy Star Tier 2 compliance.
V_REF	2.50 V ±2% - Precision internal reference for CV regulation loop; enables ±3% output voltage accuracy without secondary feedback.
V_ZCDT	60 mV typ. negative-going trigger threshold - Ensures reliable MOSFET turn-on at transformer demagnetization valley, minimizing switching loss.
V_CCON/V_CCOFF	13 V / 10 V thresholds - Hysteresis ensures stable startup and shutdown; supports self-biasing from auxiliary winding or HV start-up generator.

Pinout & Package

ALTAIR04-900 is housed in a SO16N package with exposed drain pads (pins 13–16) thermally connected to the internal metal frame for enhanced heat dissipation. The copper area beneath drain pins is mandatory for thermal management per datasheet layout guidance.

Pin	Circuit Role	Design Meaning
1,2	SOURCE	MOSFET source node and current sense input; senses peak drain current via external resistor for OCP and CC regulation.
3	Vcc	IC supply rail; charged by internal HV start-up generator or auxiliary winding; powers all logic and gate driver circuits.
4	GND	Common return for signal and gate-drive paths; must be separated from pulsed current returns to avoid noise coupling.
5	IREF	CC regulation reference node; external capacitor sets average output current; voltage automatically adjusted for line-independent current limit.
6	ZCD/FB	Dual-function pin: detects transformer demagnetization (for QR turn-on) and samples output voltage (for CV regulation).
7	COMP	Error amplifier output; connects to RC compensation network to stabilize CV/CC control loops and ensure dynamic response.
8–11	N.A.	No internal connection; must remain unconnected to avoid parasitic coupling or thermal stress.
12	N.C.	Not internally connected; electrically floating; no routing or soldering required.
13–16	DRAIN	High-voltage MOSFET drain terminals; share current path and thermal mass; require large copper pour for heatsinking.

Key Features

Feature	Design Value
Optoless primary-side CV regulation	Eliminates optocoupler, TL431, and secondary bias winding - reduces BOM count, improves reliability, and cuts cost in metering and industrial SMPS.
Adjustable mains-independent CC limit	Enables safe overload/short-circuit handling across universal input (85–430 V AC) without recalibration - critical for auxiliary supplies in variable-line environments.
Quasi-resonant valley switching	Reduces MOSFET turn-on loss and EMI by synchronizing switching with transformer demagnetization zero-crossing - improves efficiency >85% at full load.
Burst-mode at ultra-light load	Lowers average switching frequency to ~300 Hz under no-load, achieving <150 mW input power - meets IEC 62301 standby requirements.
Hiccup-mode OCP with brownout detection	Auto-restarts after fault clearance while blocking operation during auxiliary winding disconnection or low-Vin - prevents transformer saturation and diode failure.

Applications

Energy Metering SMPS

Industrial 3-Phase Auxiliary Supply

Use Scenario: Powering metrology ICs, RTCs, and communication modules in DIN-rail mounted electricity meters operating from 3-phase 400 V AC mains.

IC Role / Device Role / Timing Role: Primary-side flyback controller providing isolated 5 V/12 V outputs; performs CV/CC regulation and valley-triggered switching.

Use Value: Eliminates optocoupler drift and secondary sensing errors, enabling ±0.5% output stability over temperature and 10-year lifetime - meeting IEC 62053 accuracy class.

Use Scenario: Generating bias rails for PLC I/O modules, motor drives, and protection relays in factory automation systems with fluctuating 3-phase input.

IC Role / Device Role / Timing Role: High-voltage flyback controller with 900 V MOSFET; manages wide-input (200–800 V DC) and maintains regulation during line sags.

Use Value: Mains-independent CC limit ensures consistent short-circuit current (e.g., 200 mA) regardless of input voltage - preventing fuse nuisance trips and field failures.

AC-DC Adapters for Industrial IoT Gateways

Smart Grid Communication Module Supplies

Use Scenario: Compact 10 W adapter powering ARM-based gateways interfacing with Modbus, CAN, or LoRaWAN radios in harsh electrical environments.

IC Role / Device Role / Timing Role: Integrated controller+MOSFET performing QR flyback with burst-mode; handles 85–265 V AC input and 12 V/0.8 A output.

Use Value: SO16N package with drain-exposed pads enables natural convection cooling without heatsink - reducing adapter size and cost while meeting EN 55032 Class B EMI.

Use Scenario: Isolated DC-DC stage in PMU (Phasor Measurement Unit) or substation RTU supplying FPGA, ADC, and RF transceivers from 125 V DC battery backup.

IC Role / Device Role / Timing Role: Off-line regulator accepting 80–300 V DC input; provides regulated 3.3 V/500 mA with low standby draw during grid outage.

Use Value: HV start-up generator sustains operation down to 40 V DC input, ensuring uninterrupted communication during brownouts - critical for IEEE C37.118 compliance.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage primary-side flyback controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
ICE5QSBG	800 V integrated MOSFET, fixed 65 kHz frequency, no valley-skipping; requires external ZCD circuit for QR.	Lacks primary-side CC regulation and mains-independent current limiting - unsuitable for short-circuit-safe auxiliary supplies.	Prefer ALTAIR04-900 where adjustable CC limit and true QR operation are required for energy metering or industrial safety.
LNK3696P	725 V MOSFET, 132 kHz max, no integrated HV start-up; relies solely on auxiliary winding for bias.	Cannot sustain operation during CC regulation when auxiliary voltage collapses - risks latch-up in overload conditions.	ALTAIR04-900's dual-bias capability (HV start-up + auxiliary winding) provides superior fault resilience in unregulated industrial inputs.

Compared with ICE5QSBG and LNK3696P, ALTAIR04-900 uniquely combines 900 V ruggedness, optoless CV/CC regulation, valley-skipping, and autonomous HV start-up - making it the only choice for safety-critical, wide-input auxiliary supplies requiring no secondary sensing.

Availability

ALTAIR04-900 is available at Aetrix Electronics and suitable for energy metering SMPS, industrial 3-phase auxiliary supplies, and AC-DC adapters requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for ALTAIR04-900 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The ALTAIR series targets high-reliability off-line power conversion, specifically engineered for primary-side regulated flyback topologies in utility-grade metering and industrial control systems where optocoupler elimination and avalanche ruggedness are mandatory.

FAQ

What is the purpose of the ZCD/FB pin in ALTAIR04-900?

The ZCD/FB pin serves two simultaneous functions: it detects transformer demagnetization via negative-going edges to enable quasi-resonant valley switching, and it samples the auxiliary winding voltage at demagnetization end to perform primary-side constant voltage regulation. Its 60 mV trigger threshold and 3.3 V upper clamp ensure noise-immune timing and accurate voltage feedback without secondary components.

How does ALTAIR04-900 achieve mains-independent constant current regulation?

ALTAIR04-900 uses line voltage feed-forward through the ZCD/FB pin current: the IC monitors the sourced current during MOSFET on-time and adjusts the peak drain current reference to maintain constant average output current regardless of input voltage. This is implemented via internal circuitry tied to the IREF pin capacitor, eliminating need for external line-sensing resistors.

Can ALTAIR04-900 operate without an auxiliary winding?

No - an auxiliary winding is mandatory for both CV/CC regulation and proper ZCD/FB functionality. While the HV start-up generator powers the IC initially from the bulk capacitor, sustained operation requires the auxiliary winding to supply Vcc during normal regulation and to provide the voltage signal for output monitoring and demagnetization detection.

What thermal design considerations apply to the SO16N package?

The SO16N package requires copper pour under pins 13–16 (DRAIN) connected to a thermal pad or heatsink, as these pins carry high-current paths and dissipate most power. R_thj-pin is 10 °C/W, but R_thj-amb is 110 °C/W - meaning board-level copper area is essential to keep junction temperature below 150 °C at 0.9 W dissipation. GND pin (4) must be isolated from noisy return paths to prevent COMP instability.

ALTAIR04-900 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Active

Output Isolation:: Isolated

Internal Switch(s):: Yes

Voltage - Breakdown:: 900V

Topology:: Flyback

Voltage - Start Up:: 13 V

Voltage - Supply (Vcc/Vdd):: 11.5V ~ 23V

Duty Cycle:: -

Frequency - Switching:: Up to 166kHz

Power (Watts):: -

Fault Protection:: Current Limiting, Short Circuit

Control Features:: -

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Supplier Device Package:: 16-SO

Mounting Type:: Surface Mount

ALTAIR04-900 FAQ

1.How can I place an order for ALTAIR04-900 through Aetrix?

Please submit a Request for Quotation (RFQ) for ALTAIR04-900 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for ALTAIR04-900 reliable?

The price and inventory of ALTAIR04-900 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ALTAIR04-900 is usually 5 days.

3.What payment methods are accepted for ALTAIR04-900?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ALTAIR04-900 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ALTAIR04-900?

ALTAIR04-900 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ALTAIR04-900 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for ALTAIR04-900?

For technical support, including ALTAIR04-900 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ALTAIR04-900 requirements.

6.How does Aetrix verify that ALTAIR04-900 is sourced from the original manufacturer or authorized distributors?

All ALTAIR04-900 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ALTAIR04-900 meets industry standards.

7.What is the process for return or replacement of ALTAIR04-900?

All ALTAIR04-900 units undergo pre-shipment inspection (PSI). If there is an issue with ALTAIR04-900, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The ALTAIR04-900 part is unused and in its original packaging.

Return procedure for ALTAIR04-900:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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