L6585D_07 STMICROELECTRONICS [STMicroelectronics], L6585D_07 Datasheet - Page 13

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

L6585D
5.1.2
Ignition (time interval B
When the voltage at pin T
impedance state and C
by C
The ignition time is the time necessary to EOI voltage to reach 1.9V, so, by means of simple
calculation:
Equation 3
During this phase, the half-bridge current control can limit the maximum voltage applied
to the lamp by forcing small frequency increases whenever the half-bridge sense resistor
voltage exceeds the HBCSH threshold (see the “Half-Bridge current control” paragraph).
Figure
ignite for a time longer than the pre-heating one (counted by a cycle charge/discharge of the
T
UVLO.
CH
IGN
pin), the IC is stopped, enters low consumption and waits for either a re-lamp or an
5, centre and right, shows the L6585D behavior as the lamp gets older; if it doesn’t
*R
PRE
that defines the ignition time and the frequency shift starts.
IGN
CH
is exponentially charged according to the time constant
drops down to 1.50V (typ.), the pin EOI is driven in high
Figure
T
IGN
5)
=
3 C
⋅
IGN
⋅
R
PRE
Application information
τ
given
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