Driver and switching circuit
Pin 1 is the input for the driver of the output stage. The signal at pin 1 is also applied to pin 3 which
is the input of a switching circuit (pin 1 and 3 are connected via external resistors).
This switching circuit rapidly turns off the lower output stage when the flyback starts and it,
therefore, allows a quick start of the flyback generator. The maximum required input signal for the
maximum output current peak-to-peak value of 3 A is only 3 V, the sum of the currents in pins 1
and 3 is then maximum 1 mA.
During scan, the capacitor between pins 6 and 8 is charged to a level which is dependent on the
value of the resistor at pin 8 (see Block diagram ).
When the flyback starts and the voltage at the output pin (pin 5) exceeds the supply voltage, the
flyback generator is activated.
The supply voltage is then connected in series, via pin 8, with the voltage across the capacitor
during the flyback period. This implies that during scan the supply voltage can be reduced to the
required scan voltage plus saturation voltage of the output transistors. The amplitude of the flyback
voltage can be chosen by changing the value of the external resistor at pin 8. It should be noted
that the application is chosen such that the lowest voltage at pin 8 is > 1,5 V, during normal
When there is no deflection current, for any reason, the voltage at pin 8 becomes less than 1 V,
the guard circuit will produce a d.c. voltage at pin 7. This voltage can be used to blank the picture
tube, so that the screen will not burn in.
The internal voltage stabilizer provides a stabilized supply of 6 V to drive the output stage, so the
drive current is not affected by supply voltage variations.
Pins 2 and 4 are externally connected to ground.
Supply voltage output stage
Input voltage switching circuit
External voltage at pin 7
Repetitive peak output current
Non-repetitive peak output current (note 1)
Repetitive peak output current of flyback generator
Non-repetitive peak output current of flyback
generator (note 1)
Storage temperature range
Operating ambient temperature range
Operating junction temperature range
(the output current at pin 5 should not exceed 2.5A)