Datenblatt-Suchmaschine für elektronische Bauteile |
|
TDA8143 Datenblatt(PDF) 5 Page - STMicroelectronics |
|
TDA8143 Datenblatt(HTML) 5 Page - STMicroelectronics |
5 / 9 page APPLICATION INFORMATION The conventional deflection system is shown in Figure 3. The driving circuit consists of a bipolar power transistor driven by a transformer and a medium power element plus some passive compo- nents. During the active deflection phase the collector current of the power transistor is linearly rising and the driving circuitry must be adapted to the required base current in order to ensure the power transistor saturation. According to the limited components number the typical approach of the present TVs provides only a rough approximation of this objective ; in Figure 4 we give a comparison between the typical real base current and the ideal base current waveform and the collector waveform. The marked area represents a useless base cur- rent which gives an additional power dissipation on the power transistor. Furthermore during the turn-ON and turn-OFF tran- sient phase of the chassis the power transistor is extremely stressed when the convenctional net- work cannot guarantee the saturation ; for this reason, generally, the driving circuit must be care- fully designed and is different for each deflection system. The new approach, using the TDA8143, over- comes these restrictions by means of a feedback principle. As shown in Figure 4, at each instant of time the ideal base current of the power transistor results from its collector current divided by such current gain which ensure the saturation ; thus the required base current Ib can be easily generated by a feed- back transconductance amplifier gm which senses the deflection current across the resistor Rs at the emitter of the power transistor and delivers : Ib = RS • gm • Ie The transconductance must only fulfill the condi- tion : 1 1 + βmin ⋅ 1 RS < gm < 1 RS where β is the minimum current gain of the transitor. This method always ensures the correct base cur- rent and acts time independent on principle. For the turn-OFF, the base of the power transistor must be discharged by a quasi linear time decreas- ing current as given in Figure 5. Conventional driver systems inherently result into a stable condition with a constant peak current magnitude. V CC + V IN IB I C I D YOKE DEFLECTION CIRCUIT HORIZONTAL TRANSFORMER DRIVING CIRCUIT Figure 3 : Conventional Horizontal Deflection System for TVs TDA8143 5/9 |
Ähnliche Teilenummer - TDA8143 |
|
Ähnliche Beschreibung - TDA8143 |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |