Vertical deflection and guard circuit Integrated Circuit Chip 110∑ TDA3654

 
Vertical deflection and guard circuit (110˚)
TDA3654
TDA3654Q
 
GENERAL DESCRIPTION
The TDA3654 is a full performance vertical deflection output circuit for direct drive of the deflection coils and can be used for a wide range of 90° and 110° deflection systems. A guard circuit is provided which blanks the picture tube screen in the absence of deflection current.
 
Features
• Direct drive to the deflection coils
• 90° and 110° deflection system
• Internal blanking guard circuit
• Internal voltage stabilizer
 
QUICK REFERENCE DATA                                                                
Output voltage                                          V_5-2                max.        60 V
Output current (peak-to-peak)                  I_5(p-p)          max.        3 A
Supply voltage                                          V_9-2             max.        40 V
Guard circuit output voltage                      V_7-2             max.        5,6 V
Operating ambient temperature range      T_amb           −25 to +60 °C
Storage temperature                                 Tstg             −55 to +150 °C       
 
THERMAL RESISTANCE
From junction to mounting base               R_{th j-mb}             3,5 to 4   K/W
 
PACKAGE OUTLINES
TDA3654 : 9-lead SIL; plastic power (SOT131) .
TDA3654Q : 9-lead SIL bent to DIL; plastic power (SOT157) .
 

 
FUNCTIONAL DESCRIPTION
 
Output stage and protection circuits
 
The output stage consists of two Darlington configurations in class B arrangement. Each output transistor can deliver 1,5 A maximum and the VCEO is 60 V.
Protection of the output stage is such that the operation of the transistors remains well within the SOAR area in all circumstances at the output pin, (pin 5). This is obtained by the cooperation of the thermal protection circuit, the current-voltage detector and the short circuit protection.
Special measures in the internal circuit layout give the output transistors extra solidity, this is illustrated in Fig.5 where typical SOAR curves of the lower output transistor are given. The same curves also apply for the upper output device. The supply for the output stage is fed to pin 6 and the output stage ground is connected to pin 4.
 
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.
 
Flyback generator
 
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 Fig.1).
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 operation.
 
Guard circuit
 
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.
 
Voltage stabilizer
 
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.
 
RATINGS
Limiting values in accordance with the Absolute Maximum System (IEC 134).
Pins 2 and 4 are externally connected to ground.
 
Voltages
 
Output voltage                                     V_5-4                  0 to 60 V
Supply voltage                                     V_9-4                  0 to 40 V
Supply voltage output stage                V_6-4                  0 to 60 V
Input voltage                                        V_1-2                  0 to V_9-4 V
Input voltage switching circuit               V_3-2                  0 to V_9-4 V
External voltage at pin 7                       V_7-2                  0 to 5,6 V
 
Currents
 
Repetitive peak output current                                                         ± I_5RM      max.     1,5 A
Non-repetitive peak output current (note 1)                                     ± I_5SM       max.      3 A
Repetitive peak output current of flyback generator                        I_8RM          max.     + 1,5 A
                                                                                                                                     − 1,6 A
Non-repetitive peak output current of flyback generator (note 1)     ± I_8SM       max.      3 A
 
Temperatures
 
Storage temperature range                                                              T_stg            −65 to + 150 °C
Operating ambient temperature range (see Fig.3)                           T_amb          −25 to + 60 °C
Operating junction temperature range                                              T_j               −25 to + 150 °C
(the output current at pin 5 should not exceed 2.5A)