Electronic Components Datasheet Search |
|
LM2432 Datasheet(PDF) 10 Page - Texas Instruments |
|
LM2432 Datasheet(HTML) 10 Page - Texas Instruments |
10 / 17 page + + RIK VIK RD VCC VBB IK, R VIN VOUT KR To IK interface circuit or RGB SURFHVVRU¶V ,. voltage input DPROT IK current from other two LM2432s IK, R + IK, G OBSOLETE LM2432 SNOSAL4E – MARCH 2005 – REVISED APRIL 2013 www.ti.com CATHODE CURRENT OUTPUT FOR IK FEEDBACK SYSTEMS IK Feedback Systems IK feedback was developed to accurately bias the CRT and continuously calibrate it to the correct cut-off and/or drive levels over the useful life of the CRT. RGB video processors that use IK feedback to automatically adjust only cut-off, or black level, are realized by a 1-point calibration system. A few trade names for this system are Auto Kine Bias (AKB) and Black Current Stabilization (BCS). RGB processors that can automatically adjust both cut-off and drive, or white level, are realized by a 2-point calibration system. This is commonly known as Continuous Cathode Calibration (CCC). For convenience, some 2-point RGB processors may be programmed to 1-point operation if drive calibration is not required. The LM2432 is compatible with both 1- and 2-point systems. To be compatible with various RGB processors, an interface circuit may be needed in the feedback path between the LM2432 IK output and the processor's IK input. This feedback circuit depends on the RGB processor and feedback topology (voltage or current) used. Because each processor has its own IK input signal and topology requirements, it is outside the scope of this data sheet to describe each feedback circuit in detail. For more information, please refer to the RGB processor data sheet or contact your local TI Sales Office with your specific application requirements. Feedback Topologies RGB processors that use voltage feedback require the LM2432 IK current to be converted to voltage via a resistor (RIK) to ground. This IK voltage, VIK, will be fed back to the IK input of the RGB processor through an interface circuit, which will be AC or DC coupled depending on the processor's IK input requirement. For proper feedback operation, some processors may require an emitter follower to isolate the IK input from the high impedance of the resistor. During the closed-loop IK measurement interval, the IK input voltage will be sampled and compared with the processor's internal reference voltage to automatically calibrate the video levels for the next field. The value of RIK is crucial, since it establishes the IK voltage and consequently, the operating point of the CRT. Once a stable operating point is established with a properly chosen resistor, this point can be fine- tuned using the adjustment range of the processor's RGB cut-off and/or gain controls via the I2C-bus. After the IK measurement interval (usually at the end of blanking), normal video will resume and high currents will flow out of the IK output. These high video currents will produce large IK voltages across the resistor that can exceed the maximum voltage rating for VIK. Therefore, it is recommended to use a high-speed diode (DPROT) to clamp the LM2432 IK output to a safe level (preferably VBB or a lower supply). If a zener diode is used instead, it may be necessary for the RGB processor to have IK leakage compensation for the leakage current attributed to the zener. Lastly, it is possible to use a single RIK resistor to set the IK voltage for all three LM2432s. See a simplified voltage feedback interface circuit in Figure 14. Figure 14. Simplified IK Interface for Voltage Feedback Systems RGB processors that use current feedback do not require voltage conversion. The LM2432 IK current can be fed back directly to the IK input of the RGB processor, although some protection circuitry will be needed to protect the RGB processor and LM2432. During the closed-loop IK measurement interval, the voltage of the RGB processor's IK pin will be internally clamped, and the IK current will be sampled and compared with the processor's internal reference current to calibrate the video levels. The operating point of the CRT can be fine- tuned using the adjustment range of the processor's RGB cut-off and/or gain controls via the I2C-bus. When 10 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM2432 |
Similar Part No. - LM2432 |
|
Similar Description - LM2432 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |