L6585D_07 STMICROELECTRONICS [STMicroelectronics], L6585D_07 Datasheet - Page 16

• Manufacturer Part Number: L6585D_07
• Description: Combo IC for PFC and ballast control
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

End of life – window comparator
16/25
The four possible configurations are summarized in the following table, together with the
value of resistance to be connected to the EOLP pin in order to obtain the desired setting:
Table 5.
Tracking reference: this setting is suitable for the block capacitor to ground configuration
(Figure
In this case the window comparator centre is set by the CTR voltage that is internally
transferred to the EOL structure.
The effect of rectification appears as shifting of the DC voltage component across the block
capacitor, which, under normal conditions, equals one half of the PFC output voltage.
A signal proportional to the DC block capacitor voltage is sent to the EOL-R pin by means of
a resistive divider (R
designed to set the EOL-R voltage equal to CTR under nominal condition.
Fixed reference: this setting is suitable for the lamp to ground configuration
The effect of rectification appears as shifting of the DC lamp voltage.
A resistive divider (R
condition, that is an AC signal with zero average value whereas in case of asymmetric
rectification the DC value can shift either in positive or negative direction. Two Zener diodes
can be connected back-to-back between the EOL-R pin and the centre of the resistive
divider.
The Zener voltages should differ by an amount as close as possible to the double of the
internal reference to have a symmetrical detection, as it can easily obtained from the
following equations:
●
●
where V
comparator.
To avoid an immediate intervention of the EOL protection, a filtering is introduced; as long as
the fault condition persists, the Tch internal generator charges the C
it opens. If this fault condition is still present when the Tch voltage decreases down to 1.5V,
then the half bridge is stopped, otherwise (if the fault disappears) the counting is stopped
and reset.
220K = R
75K = R
22K = R
V
V
EOLP resistor
R
UP
DOWN
EOLP
6, left).
UP
= V
EOLP
EOLP
EOLP
and V
Configuration of the EOLP pin
> 620K
= V
REF
= 270K
= 91K
= 27K
REF
+ W/2 + V
DOWN
E1
E1
– W/2 – V
and R
and R
are the V
Z1
Symbol
E2
R
R
R
R
E2
+ V
FH
Z2
TL
FL
TL
); the dividers R
) senses the voltage across the lamp under normal
K
R2
– V
values (equal in absolute value) that trigger the window
R1
Tracking with CTR
Tracking with CTR
Reference
Fixed 2.5V
Fixed 2.5V
E1
and R
E2
and R
P1
Half–window amplitude
D
and R
up to 4.63V and then
± 720mV
± 220mV
± 220mV
± 720mV
P2
(Figure
must be
6, right).
L6585D