FAN7319 Datasheet, PDF (18/23 Pages) Fairchild Semiconductor – LCD Backlight Inverter Drive IC

Short-Lamp Protection
If
the
minimum
of
the
rectified
OLR
voltages
(
V min
OLR
)
is
less than 0.5V in normal mode, the IC is shut down after
a delay of 20ms, as shown in Figure 44. In DCR mode
(VENA>2.5V),
if
V min
OLR
is
less
than
0.5V
in
normal
mode;
the IC operates normally without shutdown, as shown in
Figure 45. This protection is disabled in striking mode to
ignite lamps reliably.
CMP-High Protection
If CMP is 2.5V in normal mode, OLP peak voltage is
higher than ADIM voltage and CMP voltage is holding at
2.5V. If CMP is 2.5V in normal mode, OLP peak voltage
is lower than ADIM voltage and CMP is charged by 1µA
current source. If CMP is higher than 3V, the IC is shut
down after a delay of 500ms, as shown in Figure 46. This
protection is disabled in striking mode to ignite lamps
reliably. To remove CMP-HIGH protection, connect a
1MΩ resistor to CMP capacitor in parallel. Unless 1µA
sourcing current flows into the resistor, CMP voltage
cannot be charged.
Figure 44. Short-Lamp Protection in Normal Mode
Figure 46. CMP-High Protection in Normal Mode
Thermal Shutdown
The IC provides a function to detect abnormal over-
temperature. If the IC temperature exceeds
approximately 150°C, the thermal shutdown triggers.
Figure 45. Short-Lamp Protection in DCR Mode
© 2010 Fairchild Semiconductor Corporation
FAN7319 • 1.0.1
18
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