KKA3354

TECHNICAL DATA IC for Electronic Ballasts Short Description The bipolar monolithic integrated circuit triggers, monitors and turns-off RF-oscillation of an electronic ballast for fluorescent lamps dependent on several controland monitoring functions. KKA3354 Features Minimum wiring complexity Overtemperature protection without external components Malfunction detection Timer output Automatical reignition after lamp change Pinning Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6 Pin 7 Pin 8 TM CT TR GND EI LW S VCC temperature mode selection clock generator trigger output, turn-off attenuation, oscillation detector connection to ground error indication input input of lamp change switching output of the timer supply voltage Block diagram Characteristics of the IC • The KKA3354 is a control- and monitoring-IC to drive an electronic ballast for fluorescent lamps. • The IC actuates the oscillation of a self-oscillating circuit for generation of RF-shaped lamp current by means of trigger pulses. After successful excitation the oscillation is monitored and further trigger pulses are blocked. • The IC has a timer with low-active output which is activated for one second after supply voltage was applied. The switching output is effective for pre-heating and ignition systems. • The IC consists an error indication input. In case of error indication the IC stops oscillation. Enquiry cycles realize interference reduction. • After lamp change the IC starts oscillation again. • The IC protects from overtemperature cutting oscillation. It is programmable when the oscillator circuit shall be triggered again. 1 KKA3354 Functional Description At the moment of current feeding at terminal VCC, the IC generates the supply voltage via backup capacitor externally connected. As soon as an internal switching threshold of 7 V is reached, trigger pulses are delivered at the output TR with a repetition instalment of 960 µs. After successful triggering of the oscillator circuit, an oscillation detector guarantees blocking of further trigger pulses. It identifies a stable oscillating process, after a minimum of oscillations is detected per timing. As soon as a switching threshold of 8 V is reached, all logic units are reset and the timer output S is activated as well. The IC starts a counter, which interrups the control after one second. Furthermore, the IC monitors the temperature and the oscillation circuit from a supply voltage of 8 V. The comparator input EI is useful for error detection. Voltage > 3.75 V, applied at EI, are evaluated as error signals. The error signal is enqired and registered within a cycle repeating every 960 µs. After registration of the error signal, a counter starts to generate a delay of one second. After this delay time, the voltage at EI is evaluated again. The error storage is set only after a second error, appearing within a directly following evaluation cycle. This error storage is resettable by a short-time power supply disconnection, or with input LW connected via a change of lamp. The error storing causes the cutting further triggers and the control of the turn-off transistor as well, which turns the output TR to ground. Therefore, the turn-off transistor prevents the control of the oscillator circuit, attenuating it extremly quickly. Thereby, the current consumption increases by the control of the turn-off transistor. This current amounts more than 5 mA, that the supply voltage across the backup capacitor at pin VCC breaks down (because nominal current feed is less 5 mA). With a switching threshold of 6 V, the control current of the turn-off transistor is switched off, that enables the supply voltage to rise up to the limiting voltage. Because the trigger pulse gate, blocked by the error memory, the oscillation can’t start again. With error storing and attenuation of the oscillation by overtemperature it can be defined via selection of the temperature mode, whether the oscillation is automatically triggered after cooling-down of the assembly, or only after mains disconnection. Absolute Maximum Ratings current consumption peak current for t< 100 µs input voltage error indicator input voltage lamp exchange input voltage difference between VLW and VCC for divider factor 16 via LW input current at pin TM negative current load for t