HVLED815PFTR Datasheet, PDF (28/36 Pages) STMicroelectronics – Offline LED driver with primary-sensing, high power factor up to 15 W

Device description
HVLED815PF
Figure 22. High power factor implementation connection - single range input
DRAIN
Rdmg
DMG
Feedf orward .
Logic1
Rf b
Aux
CC
IFF Block1
CC
PWM
LOGIC2
Rf f
CS
RPF
SOURCE
R1
ROS
Rsense
VIN (after bridge diode)
RA
RB
COS
AM13572v1
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 I_DMG
needed to guarantee the correct functionality of the internal circuitry:
Equation 16
where N_AUX and N_PRIM are the auxiliary and primary turn's number respectively and
V_{IN_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 V_OUT 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 N_AUX and N_SEC are the auxiliary and secondary turn's number respectively and V_REF
is the internal reference voltage (V_REF =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 R_A/R_B resistor
offset circuitry.
The R_A, R_B, R_OS 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:
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Doc ID 023409 Rev 4