STEVAL-ILB008V1 STMicroelectronics, STEVAL-ILB008V1 Datasheet - Page 25

BOARD EVAL BALLAST FOR L6585DE

STEVAL-ILB008V1

Manufacturer Part Number
STEVAL-ILB008V1
Description
BOARD EVAL BALLAST FOR L6585DE
Manufacturer
STMicroelectronics
Type
Power Factor Correctionr

Specifications of STEVAL-ILB008V1

Main Purpose
Lighting, Ballast Control
Embedded
No
Utilized Ic / Part
L6585DE
Primary Attributes
4 x 18w, T8 Lamps
Secondary Attributes
Preheating Ignition
Input Voltage
90 V to 265 V
Product
Power Management Modules
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
For Use With/related Products
L6585DE
Other names
497-10544
L6585DE
6.6
6.7
6.8
Over-current protection
The appearance of over-current and hard switching events are related to a symmetrical
increase of the ohmic resistance of the two cathodes. The overall effect results in an
increased equivalent resistance of the lamp and a subsequent modification of the
resonance curve of the resonance network (see
Figure 14. Resonance curve modification due to lamp ageing
The increasing of the resonant peak causes over-current that is managed by the L6585DE
in the same way as in ignition mode, but the limiting threshold and checking threshold are
respectively 1.05 V and 0.82 V.
Hard switching protection
When F
purely resistive. In this case, zero voltage switching is no longer present and the MOSFET
experiences high current spikes at turn on. The voltage at HBCS pin shows these peaks
whose voltage value can be greater than 3 V with a duration that depends on how close the
resonant frequency and the operating frequency are. Typical values go from 40 ns to around
200 ns. These spikes may overheat the MOSFETs but, if correctly detected, can prevent the
risk of working below the resonance frequency (capacitive mode).
The L6585DE can detect these spikes by means of a 2.75 V threshold on HBCS pin, and a
counter that shuts down the IC if 350 (typ.) subsequent spikes are detected.
This protection is blanked both during preheating and ignition.
Choke saturation protection
Ballast choke saturation implies that very high currents flow into resonance network and an
almost instant modification of the resonance curve occurs in a way that the operating point
lies immediately in capacitive mode. Steady operation in capacitive mode heavily damages
the ballast.
RUN
is equal to the peak of the resonance curve, the load seen by the half-bridge is
frun
Figure 14
New lamp
).
Old lamp
Ballast section
25/33

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