TA9687GN datasheet(8/14 Pages) O2MICRO

8 / 14 page

ta9687

CONFIDENTIAL

ta9687-DS-1.0

Page 7

The approximate shutdown delay time is

calculated by the following equation.

]

[

]

[

TIMER

DELAY

To resume operation, toggle the ENA signal or

restart VDDA.

8. Over-Voltage and Over-Current

Protection

Over-voltage and over-current protection are

monitored by the voltage on VSEN (pin 1).

During normal operation, if a CCFL is damaged

or removed, the voltage at VSEN increases.

Once the voltage at VSEN exceeds the user-

defined, preset voltage set by OVPT (pin 15), the

driver output duty cycle is regulated and the

shutdown delay timer is activated. OVPT sets

the overall protection threshold voltage that is

lower than ~3V (VSEN threshold).

Once the

voltage at TIMR pin reaches ~3V, the IC will shut

down and latch.

OVPT voltage setting is

determined by a resistor divider (R17 and R18)

connected to the OVPT.

The approximate shutdown delay time is

calculated by the following equation.

]

[

]

[

TIMER

DELAY

To resume operation, toggle the ENA signal or

restart VDDA.

9. Dimming Control

External PWM dimming is implemented by

applying external PWM pulse to PWM (pin 13).

When PWM is higher than 2V, dimming is ON

and vice versa.

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