LTC1697

1697f

signal should be in the range of 150Hz to 500Hz.

Lamp Feedback

In a typical application, the LAMP pin is connected to the

low voltage side of the lamp. The lamp pin is internally

connected to ground by a ~50Ω resistor. This resistor will

lamp current. The lamp feedback circuit removes a current

current through the 50Ω resistor.

the programming current, and the control for the switch-

ing controller meet. A single capacitor must be connected

loop. Careful consideration should be given to the value of

capacitance used. A large value (1µF) will give excellent

stability at high lamp currents but will result in degraded

line regulation. On the other hand, a small value (10nF) will

result in overshoot and poor load regulation. The value

chosen will depend on the maximum load current and

dimming range. After these parameters are decided upon,

line regulation becomes unacceptable. A typical value for

compensation please refer to Application Note 65 or

consult the factory.

transformer from an overvoltage condition that can occur

when the lamp is open or not present. Connect this pin

through a resistor to the emitters of the drive transistors

former specifications for transformer voltage ratings.

Thermal Shutdown

This IC includes overtemperature protection that is in-

tended to protect the device during momentary overload

conditions. Junction temperature will exceed 125°C when

overtemperature protection is active. Continuous opera-

tion above the specified maximum operating junction

temperature may result in device degradation or failure.

Shutdown Operation

There are two ways to place the LTC1697 in shutdown. The

50mS. For normal operation, both pins must be pulled

APPLICATIO S I FOR ATIO