CA3224E Automatic Picture Tube Bias Control Circuit November 1996 Features Description • Automatic Picture Tube Bias Cutoff Control The CA3224E is an automatic picture tube bias control circuit used in color TV receiver CRT drive circuits. It is used to provide dynamic bias control of the grey scale both initially and over the CRT operating life, compensating for CRT cutoff changes. • Automatic Background Color Balance • Eliminates Grey Scale Adjustments • Compensates for Cathode-to-Heater Leakage • Electrostatic Protection on All Pins • Servo Loop Design • Wide Dynamic Range • Three-Gun Control • Minimal External Components Ordering Information PART NUMBER CA3224E TEMP. RANGE (oC) -40 to 85 PACKAGE 22 Ld PDIP PKG. NO. The CA3224E provides automatic continuous control of the cutoff current in each gun of a three-gun color CRT. From an input pulse amplitude proportional to the difference between the desired and the actual CRT cutoff, a gated sample/hold circuit generates a DC correction voltage which correctly biases the CRT driver circuit. The sample/hold bias correction takes place each frame following the vertical blanking. Figure 1 shows a block diagram of the CA3224E. The functions include three identical servo loop transconductance amplifiers with a sample/hold switch and buffer amplifier plus control logic, internal bias and a mode switch. E22.4 Pinout CA3224E (PDIP) TOP VIEW GROUND 1 22 VCC CHANNEL 1 INPUT 2 21 CHANNEL 1 HOLD CAP CHANNEL 1 FREQ COMPENSATION 3 20 CHANNEL 1 OUTPUT CHANNEL 2 INPUT 4 19 CHANNEL 2 HOLD CAP CHANNEL 2 FREQ COMPENSATION 5 18 CHANNEL 2 OUTPUT CHANNEL 3 INPUT 6 17 CHANNEL 3 HOLD CAP CHANNEL 3 FREQ COMPENSATION 7 16 CHANNEL 3 OUTPUT VERTICAL INPUT 8 15 VREF BYPASS GROUND 9 14 AUTO BIAS LEVEL ADJUST HORIZONTAL INPUT 10 13 AUTO BIAS PULSE OUTPUT GRID PULSE OUTPUT 11 12 PROGRAM PULSE OUTPUT CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Copyright © Intersil Corporation 1999 8-56 File Number 1553.1 CA3224E Absolute Maximum Ratings TA = 25oC Thermal Information Supply Voltage (VCC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11V DC Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -1 to VCC Output Current . . . . . . . . . . . . . . . . . . . . . . . Short Circuit Protected Operating Conditions Thermal Resistance (Typical, Note 1) θJA (oC/W) PDIP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Maximum Junction Temperature (Plastic Package) . . . . . . . . 150oC Maximum Storage Temperature Range . . . . . . . . . -65oC to 150oC Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300oC Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . -40oC to 85oC Supply Voltage Range (Typical) . . . . . . . . . . . . . . . . . . . . 10V ±10% CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. NOTE: 1. θJA is measured with the component mounted on an evaluation PC board in free air. Electrical Specifications At TA = 25oC, VCC = 10V, VBIAS = 3.75V, VV (Pin 8) = VH (Pin 10) = 6.0V, S1 = A, S2 = A, See Test Circuit and Timing Diagrams PARAMETER TEST PIN NO. SYMBOL MIN TYP MAX UNITS - - 65 mA 5.6 6.0 6.4 V VIN = 7.2V, S1 = B - - 250 nA lOM+ VBIAS = 0.5V, Measure at t 6, S1 = B - - -0.8 mA lOM- VBIAS = 7.0V, Measure at t 6, S1 = B 0.8 - - mA - - 150 nA 0.97 - 1.07 - 50 - 100 mS Supply Current 22 Reference Voltage 2, 4, 6 VREF Input Current 2, 4, 6 II Output Current Source 17,19, 21 Sink Output Buffer Input Current 17,19, 21 Voltage Gain Transconductance Auto Bias Pulse Grid Pulse Output ICC Measure at t4 II VOUT = 6.5V, VIN At pins 16, 18, 20, Measure at t4 , S1 = B AV 17,19, 21 gM Measure at t6, VIN = 8mVP-P at 40kHz, S1 = B 13 VOL Measure at t1 - - 0.3 V High VOH Measure at t4 6.05 - - V Current Sink lOM- Measure at t4, S2 = B 2.5 - - mA VOL Measure at t4 - - 0.4 V VOH Measure at t1 4.2 - - V VOL Measure at t6 - - 0.4 V VOH Measure at t1 8.2 - - V Output Low Low 11 High Program Pulse Output TEST CONDITIONS Low 12 High Vertical Input 8 VV See Figure 3 - 6.0 - V Horizontal Input 10 VH See Figure 3 - 6.0 - V Auto Bias Pulse Timing Start 13 t0 to t2, Note 2 835 - 842 µs t0 to t7, Note 2 1270 - 1275 µs t0 to t3, Note 2 899 - 905 µs t0 to t5, Note 2 1080 - 1084 µs t0 to t5, Note 2 1080 - 1084 µs t0 to t7, Note 2 1270 - 1275 µs Finish Grid Pulse Timing Start 11 Finish Program Pulse Timing Start 12 Finish NOTE: 2. All time measurements are made from 50% point to 50% point. 8-57 CA3224E Test Circuit Device Description and Operation +10V (See Figures 1, 2, 4 and 5) VBIAS During the vertical retrace interval, 13 horizontal sync pulses are counted. On the 14th sync pulse the auto-bias pulse output goes high. This is used to set the RGB drive of the companion chroma/luma circuit to black level. The auto-bias pulse stays high for 7 horizontal periods during the auto-bias cycle. 3.65K 1 22 2 21 B VIN1 3 20 4 19 VOUT1 0.047 µF VIN2 B 5 18 6 17 VOUT2 0.047 µF B 0.047 µF VERTICAL INPUT 16 8 15 9 14 3.65K 0.12µF A S1 CA3224E 7 On the 15th horizontal sync pulse, the internal logic initiates the setup interval. During the setup interval, the cathode current is increased to a reference value (A in Figure 5) through the action of the grid pulse. The cathode current causes a voltage drop across R S. This voltage drop, together with the program pulse output results in a reference voltage at VS (summing point) which causes capacitor C1 to charge to a voltage proportional to the reference cathode current. The setup interval lasts for 3 horizontal periods. 3.65K 0.12µF A S1 VIN3 0.12µF A S1 47µF + +20V 3.32K 1.0K 1.50K +10V B HORIZONTAL INPUT 10 13 11 12 On the 18th horizontal sync pulse the grid pulse output goes high, which through the grid pulse amplifier/inverter, causes the cathode current to decrease. The decrease in cathode current results in a positive recovered voltage pulse with respect to the setup reference level at the VS summing point. The positive recovered voltage pulse is summed with a negative voltage pulse caused by the program pulse output going low (cutting off Diode D1 and switching in resistors R1 and R2). Any difference between the positive and negative pulses is fed through capacitor C1 to the transconductance amplifier. The difference signal is amplified in the transconductance amplifier and charges the hold capacitor C2, which, through the buffer amplifier, adjusts the bias on the driver circuit. VOUT3 20K S2 A 1.5K Components RS, R1, and R2 must be chosen such that the program pulse and the recovered pulse just cancel at the desired cathode cutoff level. CHAN FREQ 1 IN COMP HOLD CHAN CHAN FREQ CAPACITOR 1 OUT 2 IN COMP 3 2 21 AMPLIFER NO. 1 1 + gM 20 4 CHAN 2 OUT 19 18 5 AMPLIFER NO. 2 BUFFER AMP 2 HOLD CAPACITOR 1 - x1 + 3 CHAN FREQ 3 IN COMP 6 17 16 AMPLIFER NO. 3 1 - x1 BUFFER AMP 2 x1 + 3 gM CHAN 3 OUT 7 BUFFER AMP 2 HOLD CAPACITOR 3 gM MODE SWITCH VREF BIAS LOGIC 1 9 22 15 8 10 11 12 13 14 GND GND VCC VREF BYPASS VERT IN HORIZ IN GRID PULSE OUT PROG PULSE OUT AUTO BIAS PULSE OUT AUTO BIAS LEVEL ADJUST MODE SWITCH STATE 1 2 3 SET-UP SENSE OPEN FIGURE 1. FUNCTIONAL BLOCK DIAGRAM 8-58 CA3224E t1 t0 VERTICAL INPUT (PIN 8) t2 t3 t4 t5 t6 t7 VERTICAL BLANKING HORIZONTAL INPUT (PIN 10) 1 2 3 12 13 14 15 16 17 18 19 20 21 22 23 AUTO BIAS PULSE OUTPUT (PIN 13) GRID PULSE OUTPUT (PIN 11) PROGRAM PULSE OUTPUT (PIN 12) MODE SWITCH (SEE FIGURE 1) OPEN SET-UP SENSE FIGURE 2. FUNCTIONAL TIMING DIAGRAMS VERTICAL SIGNAL 0V VV 0.5ms 16.683ms HORIZONTAL SIGNAL VH fV = 59.94Hz fH = 15734.264Hz 0V 12µs 63.55 µs FIGURE 3. VERTICAL AND HORIZONTAL INPUT SIGNALS 8-59 OPEN CA3224E +230V +10V + 12K 33µF R 2.2K G 10K B +12V TO R DRIVER R CHROMA/ LUMA 2.7K CIRCUIT G RFB 160K Q1 CATH DRIVE RIN RS 560Ω 1% SUMMING POINT 200Ω TO B DRIVER R2 62K 1% Q2 BIAS 2 20 3 19 + 10µF 4 18 5 17 CA224E 6 16 7 15 12 14 22 10 9 8 13 11 0.047 BIN ROUT + 10µF GOUT GIN + 10µF + BOUT 0.047 47µF +10V R1 39K 1% TO BCH AUTO-BIAS PULSE GRID PULSE AMPLIFIER INVERTER C2 CC GIN D1 2.7K 21 0.047 TO RCH 9.1K -24V PROGRAM RGB TO BLACK LEVEL 0.12 VS 20K B 1 Q3 SG C1 BIAS 5K 1.5K 3.9K 20K AUTO BIAS LEVEL ADJUST HORIZONTAL INPUT VERTICAL INPUT NOTE: 3. One of three identical driver circuits shown. FIGURE 4. TYPICAL APPLICATION CIRCUIT Electrostatic Protection (Note) ICATHODE (mA) A B 0 SET-UP SENSE VCATHODE GRID (V) When correctly designed for ESD protection, SCRs can be highly effective, enabling circuits to be protected to well in excess of 4kV. The SCR ESD-EOS protection structures used on each terminal of the CA3224E are shown schematically in either Figures 6A or 6B. Although ESD-EOS protection is included in the CA3224E, proper circuit board layout and grounding techniques should be observed. NOTE: For further information on CA3224E protection structures refer to: AN7304, “Using SCRs as Transient Protection Structures in Integrated Circuits”, by L.R. Avery. Intersil AnswerFAX (407-724-7800) document #97304. FIGURE 5. PICTURE TUBE V-I CURVE TO ACTIVE CIRCUIT RSENSE RHOLD RHOLD POSITIVE SUBSTRATE TRANSIENT NEG. TRANSIENT PROTECT (A) PROTECT NEGATIVE POSITIVE TRANSIENT TRANSIENT PROTECT (B) PROTECT FIGURE 6A. FIGURE 6B. FIGURE 6. TRANSIENT PROTECTION 8-60 TO ACTIVE CIRCUIT CA3224E All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification. Intersil products are sold by description only. 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