Konka TDA9383 super chip power circuit TV resolution (on)

Konka TDA9383 chip color TV with a parallel super-excited switching power supply him. Power control chip for the new production of Philips TDAl6846 (N901), the internal block diagram shown in Figure 1. Pin functions and MC13020MEL datasheet and measured data shown in Table 1. Its internal settings of the independent oscillator, the oscillation frequency of a fixed model, free to adjust the model for the design and MC13020MEL price and use synchronous mode; overcurrent, overvoltage / undervoltage protection features; provides two control input voltage fault detection terminal and MC13020MEL suppliers and two terminals. Power supply circuit shown in Figure 2.

Figure 1 TDA16846 internal circuit diagram

Table 1 TDA16846 pin functions and measured data

2 super-chip TV Konka TDA9383 power supply circuit

tips and guidance: There are similar functions and TDAl6846 TDAl6847, TDAl6847 is based on the increase in TDAl6846 a discharge time bistable flip-flop. TDAl6846 feet of empty legs, and feet for the PMO TDAl6847 the output power measurement, an external RC components. TDAl6847 internal power supply to charge the external capacitor, the capacitor on the sawtooth voltage is proportional to the average output power converter.

A switching power supply circuit

1. Start and after the oscillation power switch S901, 220 V of alternating current through the VC901 bridge rectifier, C909 filter, got about 300 V DC voltage, all the way through the switching transformer 11 T901 ~ winding added to the FET switch V901 D-pole; another pass through the startup resistor R918 buck limit, by TDAl6846 of feet into, and through the internal circuitry of the N901 14 feet of the external charging capacitor C913, about 1 ~ 2 s,, C913 ends when the voltage reaches 16 V, TDAl6846 internal circuit starts, the output pulse signal from 13 feet, the R903, R902 driver switch on-V901. So the initial 11 ~ T901 winding produces a gradually increasing current, while T901 13 ~ 14 at both ends of the winding induced voltage generated by the VD902 rectifier, C913 filtered added TDAl6846 14 feet, maintain TDAl6846 power supply, the voltage as long as no less than 8 V, switching power supply will be stable and reliable operation.

2. Voltage regulator circuit.

TDAl6846 regulator designed to control two input ports, namely foot zero-crossing detection / error voltage input and the foot of the optocoupler input.

(1) When the power is activated, the switch transformer T901 of 13 to 14 winding induced voltage generated by the R919, R909 partial pressure, from TDAl6846 of feet (zero-crossing detection / error voltage input) into the house after the split into two: the way and the internal error amplifier inverting input connected to the load voltage when the input voltage pin N901 remained stable, no output error amplifier, switching power supply status unchanged ; Second, for some reason the secondary output voltage increases, feet also will increase the sampling voltage, error amplifier output voltage lower by N901 pin external capacitor C920 filter, send "on time comparator", by The control foot drive-cycle pulse narrowing, V901s on-time, so the secondary voltage drops to normal.

(Continued)