AN2870 datasheet(6/41 Pages) STMICROELECTRONICS

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L6585DE combo IC

AN2870

6/41

L6585DE combo IC

The L6585DE embeds both a PFC converter and a ballast regulator in a single SO20

package. It is intended to design complete high power electronic ballasts with a single chip.

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The most significant features of the L6585DE concern the following points:

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Transition mode PFC converter with over voltage and over current protection.

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Half-bridge controller with High voltage driver (600 Vdc) and integrated bootstrap

diode.

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3% precise, fully programmable oscillator.

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Flexibility in programming preheating time and ignition time.

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Configurable EOL detection and over current protection.

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Hard switching detection.

The PFC section achieves current mode control operating in Transition Mode. The multiplier,

together with the internal THD optimizer, reduces input current distortion, and allows

reaching very high performances also in wide-range-mains operation and large load range.

The PFC output voltage is controlled by means of a voltage-mode error amplifier and a

precise internal voltage reference.

A static and dynamic OVP protects the IC from excessive output voltage and an over current

protection turns off the PFC gate driver in case of PFC choke saturation.

The PFC driver is able to provide 300 mA (source) and 600 mA (sink).

The half bridge section is driven by a current controlled oscillator (CCO) and the internal

control logic.

The steady state frequency, the preheating frequency, the pre-heating time, the over-current

protection time and the ignition time are independently set by means of six external

components (resistors and capacitors).

An over-current protection limits the voltage across the HBCS pin acting directly on the CCO

realizing a precise closed loop control. This control lasts for a time set by the Tch pin and,

after that, if the fault condition is still present, the IC is stopped in low consumption mode.

The HBCS voltage amplitude depends on actual operating mode, then this protection can

detect either a broken lamp during ignition (in this case the current regulation implies the

lamp voltage regulation) or the symmetrical ageing of the lamp during run mode.

An internal window comparator can be simply configured setting the window amplitude or

the comparator reference in order to detect the EOL status. The programmability of

comparator reference makes the L6585DE compliant with either “lamp-to-ground” (fixed

reference) or “block capacitor-to ground” (tracking with CTR) configurations.

The drivers of the half-bridge provide 290 mA source and 480 mA sink.

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