HVLED807PF datasheet(28/36 Pages) STMICROELECTRONICS

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Device description

HVLED807PF

28/36

Doc ID 023464 Rev 5

Figure 22.

High power factor implementation connection - single range input

The components selection flow starts from Rdmg resistor: this resistor has to be selected in

order to minimize the internal feed-forward effect.

The maximum selectable value is limited is by the minimum internal current circuitry IDMG

needed to guarantee the correct functionality of the internal circuitry:

Equation 16

where NAUX and NPRIM are the auxiliary and primary turn's number respectively and

VIN_MIN is the minimum rms input voltage of the application (i.e. 88 V for 110 Vac or 175 V for

230 Vac range).

The RFB resistor defines the VOUT output voltage value in the open circuit condition (no-

load condition, i.e. no led on the output of led driver) and it can be selected using the

following relationship:

Equation 17

where NAUX and NSEC are the auxiliary and secondary turn's number respectively and VREF

is the internal reference voltage (VREF =2.51 V typ - see Table 5: Electrical characteristics).

The R1 resistor is typically selected in the range of 500 Ω -1.5 kΩ in order to minimize the

internal feed-forward effect and to minimize the power dissipation on the RA/RB resistor

offset circuitry.

The RA, RB, ROS resistors are selected to add a positive offset on CS pin in order to keep a

good line regulation over the input voltage range and cab be selected using the following

relationship:

AM13572v1

COS

DRAIN

SOURCE

IFF

Feedf orward

Logic1

Rf f

Rsense

PWM

LOGIC2

DMG

Block1

ROS

RPF

VIN (after bridge diode)

Aux

Rf b

Rdmg

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