ALTAIR05T-800TR STMicroelectronics, ALTAIR05T-800TR Datasheet - Page 3

• Manufacturer Part Number: ALTAIR05T-800TR
• Description: Switching Converters, Regulators & Controllers 800V Off-line QR Switching Regulator
• Manufacturer: STMicroelectronics

Specifications of ALTAIR05T-800TR

• Input Voltage: 11.5 V to 23 V
• Switching Frequency: 166 KHz
• Operating Temperature Range: - 55 C to + 150 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ALTAIR05T-800
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Device description
The device combines two silicon in the same package: a low voltage PWM controller and
an 800 V avalanche rugged power section.
The controller chip is a current-mode specifically designed for offline quasi-resonant flyback
converters.
The device features a unique characteristic: it is capable of providing constant output
voltage (CV) and constant output current (CC) regulation using primary-sensing feedback.
This eliminates the need for the optocoupler, the secondary voltage reference, as well as the
current sensor, still maintaining quite accurate regulation also in presence of heavy load
transients. Additionally, it is possible to compensate the voltage drop on the output cable, so
as to improve CV regulation on the external accessible terminals.
Quasi-resonant operation is guaranted by means of a transformer demagnetization sensing
input that turns on the power section. The same input serves also the output voltage
monitor, to perform CV regulation, and the input voltage monitor, to achieve mains-
independent CC regulation (line voltage feedforward).
The maximum switching frequency is top-limited below 166 kHz, so that at medium-light
load a special function automatically lowers the operating frequency still maintaining the
valley switching operation. At very light load, the device enters a controlled burst-mode
operation that, along with the built-in high-voltage start-up circuit and the low operating
current, helps minimize the standby power.
Although an auxiliary winding is required in the transformer to correctly perform CV/CC
regulation, the chip is able to power itself directly from the rectified mains. This is useful
especially during CC regulation, where the flyback voltage generated by the winding drops
below UVLO threshold. However, if ultra-low no-load input consumption is required to
comply with the most stringent energy-saving recommendations, then the device needs to
be powered via the auxiliary winding.
In addition to these functions that optimize power handling under different operating
conditions, the device offers protection features that considerably increase end-product’s
safety and reliability: auxiliary winding disconnection - or brownout – detection and shorted
secondary rectifier - or transformer’s saturation – detection. All of them are auto restart
mode.
Doc ID 17957 Rev 1
Device description
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