CA3256 HARRIS | Alldatasheet

Document overview

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Technical content

Features

  • 5 Multiplex Video Channels - 1 Independent Channel - 4 Channels with Enable
  • 4 LED Channel Indicator Outputs
  • Adjustable Video Amplifier Gain
  • High Signal-Drive Capability

Applications

  • Video Multiplex Switch
  • 7 5Ω Video Amplifier/Line Driver
  • Video Signal-Level Control
  • Monitor Switching Control
  • TV/CATV Audio/Video Switch
  • Video Signal Adder/Fader Control

Description

The CA3256 BiMOS analog video switch has five channels of CMOS multiplex switching for general-purpose video- signal control. One of four CMOS channels may be selected in parallel with channel 5. The CMOS switches are inputs to the video amplifier but may be used in bilateral switching between channels 1 to 4 and channel 5. The analog switches of channels 1 to 4 are digitally controlled with logic level conversion and binary decoding to select 1 of 4 channels. The enable function controls channels 1 to 4 but does not affect channel 5. LED output drivers are selected with the channel 1-to-4 switch selection to indicate the ON- channel. Channel 5 may be used as a monitor output for data or signal information on channels 1 to 4. The transmission gate switches shown in the block diagram of the CA3256 are configured in a “T” design to minimize feedthrough. When the switch is off, the shunt or center of the “T” is grounded. The amplifier has high input impedance to minimize the R ON transmission gate insertion loss. The amplifier output imped- ance is typically 5Ω in a complementary symmetry output. The amplifier can directly drive a nominal 75Ω coaxial cable to provide line-to-line video switching. The gain of the ampli- fier is programmable by different feedback resistor values between pins 8 and 9. Compensation may also be used between these pins for an optimally flat frequency response. An internal regulated 5V bias reference with temperature compensation permits stable direct-coupled output drive and minimizes DC offset during signal switching. Pinouts Part Number Information PART NUMBER TEMP. RANGE ( oC) PACKAGE PKG. NO. CA3256E -40 to 85 18 Ld PDIP E18.3 CA3256M -40 to 85 20 Ld SOIC M20.3 CA3256 (PDIP) TOP VIEW CA3256 (SOIC) TOP VIEW

1 CONTROL B

[ /Title (CA32 56) /Sub- ject (25MH BiMO S Ana- log Video Switch and Ampli- fier) /Autho r () /Key- words (Har- ris Semi- con- ductor, 4x1, video cross- point switch, multi- plexer multi- plexor, cable driver, 5x1, moni tor out- put, adjust- able gain, OBSOLETE PRODUCT NO RECOMMENDED REPLA CEMENT Call Central Applications 1-800-442-7747or email: centapp@harris.com

5 + (1-4) (Note) 1 Channel 1-4 1 5 1 Channel 5 Only 0 None 0 X X 0 NOTE: For Maximum Video Bandwidth, Use Single Channel Selections TG A B C ENABLE 151713 3 1 5 4 3 2 1 IN/OUT 8 AMPLIFIER OUTPUT CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4 FEED BACK LOGIC LEVEL CONV. BINARY TO

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(DIP PIN OUT) CA3256

Absolute Maximum Ratings Thermal Information P-P Operating Conditions Thermal Resistance (Typical, Note 1) θJA (oC/W) (SOIC - Lead Tips Only) 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 SpecificationsTA = 25oC, V+ = 12V; V- = GND PARAMETER SYMBOL TYPICAL VALUES UNITS Power Supply Voltage V+ to V- 10 to 17 V Power Supply Current I CC 20 mA SWITCH AMPLIFIER Open Loop Gain A OL -3 5 d B Programmable Gain, FB Adjustment Range - -0.8 A OL dB Full Power Bandwidth - 10 MHz Unity Gain Bandwidth, 1kΩ , 7pF Compensation - 25 MHz Insertion Loss -0.8 - dB Signal Feedthrough, 5MHz -66 - dB Input Impedance Z IN -1 0 k Ω Output Impedance Z OUT -5 Ω Maximum Input Voltage V I(MAX) 3 2.5 V P-P Maximum Output Voltage, Clipped V O(MAX) -7 V P-P Reference Bias Output Voltage (V8 - V-) - 5 V Differential Gain - 1 % Differential Phase - 1 Degree Off Isolation, Channel to Channel, Z IN = 75Ω -66 - dB LLC Switch Turn On/Off Time Delay - 0.5 µs Maximum LED Sink Current - 30 mA Typical Output Source Current - 16 mA Channel Control Switch A, B, C and E N Threshold (Notes 2, 3) VTH Approximately (V+ - V-)/2 V CAUTION: Connect the V- power supply voltage before or during the V+ turn-on. NOTES: 2. Threshold value is referenced to GND. 3. V TH is restricted by the equation, VTH < V+ -1. CA3256

Electrical SpecificationsTA = 25oC, V+ = 12V, VLED = 12V, V- = GND, Pin 4 = GND, Feedback Switch Closed, VHIGH = 9V, VLOW = 3V (See Figure 1), Unless Otherwise Specified PARAMETERS INPUTS CHANNEL SWITCH CONTROL MIN TYP MAX UNITS CH 1 CH 2 CH 3 CH 4 CH 5 A B C ENABLE NOTE 6 TEST PIN#PIN 15 PIN 17 PIN 1 PIN 3 PIN 13 PIN 16 PIN 18 PIN 7 PIN 6 Supply Current, VLED = 0V 0V 0V 0V 0V 0V 3V 3V 3V 3V 14 10 16 22 mA Dual Supply Current V+ = +7V, V- = -5V 0V 0V 0V 0V 0V 0V 0V 0V 7V 14/5 10 20 26 mA Amplifier Output Voltage, Open Loop V LED = 0V 0V 0V 0V 0V 0V 3V 3V 3V 3V 9 6 8.5 10 V Amplifier Output Voltage, Closed Loop, V LED = 0V 0V 0V 0V 0V 0V 3V 3V 3V 3V 9 4.8 5.1 5.4 V IOUT (MAX) (Source) Open Loop 0V 0V 0V 0V 0V 3V 3V 3V 3V 9 Note 4 - -70 -25 mA IOUT (MAX) (Sink) Open Loop 0V 0V 0V 0V 0V 3V 3V 3V 3V 9 Note 5 10 16 - mA Input Leakage Channel 1-5 3V 3V 3V 3V 3V 3V 3V 3V 3V 1, 3, 15, -15 5 15 nA Channel Control Input A, B, C, Enable Leakage 0V 0V 0V 0V 0V Measure at 3V, 9V each; Enable and Channel Switching Control Inputs 6, 7, 16, -20 10 20 nA LED Off Voltage, V OFF 0V 0V 0V 0V 0V Select Channel 0-5 2, 10, 11, 12 11.97 11.99 - V LED On Voltage, VON 0V 0V 0V 0V 0V Select Channel 0-5 2, 10, 11, 12 - 0.1 0.3 V Switch Resistance, R DS ±100µA Input Each Switch, Channel 1-4 + 5 Select Channel 1-4 9V 9V 0.8 1.1 1.4 k Ω R DS Match Calculation: (Max R DS - Min RDS )/Min RDS - - 3.6 5 % Amplifier Output Offset, VO , Feedback Switch Closed V+ = +7V, V- = -5V 0V 0V 0V 0V 0V 0V 0V 0V 7V 9 -100 45 100 mV Closed Loop Gain 3V 0V 0V 0V 0V 3V 3V 3V 9V 9 -0.5 -0.1 0.5 dB NOTES: 4. V OUT = +7V. 5. VOUT = +3V. 6. DIP Pinout. CA3256

Application Information

CMOS analog switches are available in a wide variety of forms, and have been known and used for some time. There are a number of advantages to using the CMOS transmis- sion gate as a switch:

  • Ideal Suitability to Series Cascade Arrangements
  • Simple Multiple Parallel Input Switching Arrangements
  • No Bipolar Junctions and, Hence, No Offset
  • Very Low Power Consumption
  • Wide Signal-Swing Capability
  • Fast Multiplexing and Video Switching
  • Wide Bandwidth
  • L o w R ON Channel Resistance
  • Bidirectional Signal Handling An Integrated Video-Switch Amplifier Commonly, integrated video-switch amplifiers have been fabri- cated in the bipolar technology using differential amplifiers in a current-switching mode. In this form, two differential pairs are needed for two input-signal sources. The handling of multiple sources is very much more complex. The advantages of the CMOS video-switch amplifier have already been noted. While the bipolar video switch has high output drive and switching speed as advantages, the price is high in voltage offset and cur- rent drain. The integrated device solution that is offered here is in the use of the BiMOS technology, where both the CMOS and bipolar processes complement each other to provide CMOS switching with bipolar amplifiers. The BiMOS process allows several CMOS switches to be coupled to a bipolar drive-ampli- fier in the same process to exploit the best of two technologies. Other advantages are gained when the BiMOS process is used for an IC video-switch amplifier design. The BiMOS process calls for a P-substrate and, therefore, isolated N-epi- taxial wells can be built for both N and P channel parts. The boats provide for better isolation of the N and P channels. The N and P wells in a transmission-gate cell can be switched between source and rail; therefore, they have a smaller body effect on both N and P devices, which results in better gain linearity. Where desired, oxide capacitors are available for bipolar amplifier compensation. CA3256 Video-Switch Amplifier The Block Diagram shows the functional diagram of the CA3256, which consists of five MOS channels, each com- prising a three-element T -switch. The output of the five switches is made common and fed into the input of a bipolar CONTROL INPUTS (CHANNEL SELECT) +12 V 10K 10K OUTPUT AMP FEEDBACK FEEDBACK SWITCH AMP OUT 1.1K 1.1K 1.1K 1.1K

4 GND

+12 V LLC ENABLE AND CHAN 1-4 SELECT TG-1 TG-2 TG-4 TG-3 TG-5 V+V- VBIAS VLED FIGURE 1. CA3256 TEST CIRCUIT (DIP PINOUT)

format; hence, shorting to ground is eliminated. pass-through, signal summing, or parallel distribution. minimize transients when the input is switched.

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3 TG-4

FIGURE 2. TYPICAL APPLICATION WITH DIRECT-COUPLED OUTPUT AND V- = -5V (DIP PINOUT)

FIGURE 3. TYPICAL APPLICATION WITH AC-COUPLED INPUT AND OUTPUT, AND V- = GND (DIP PINOUT)

FIGURE 4. FREQUENCY RESPONSE OF AC COUPLED CIRCUIT OF FIGURE 3

19 GAIN (dB)

FIGURE 7. OTHER TABULATED RESULTS FOR VARIATIONS OF LOAD AND FEEDBACK (V+ = +12V) NOTE: 470 Ω added to increase source drive current.

9 VOUT1

NOTE: Add R S to reduce high-frequency slewing.

simple as the one in Figure 8. high-speed CMOS and bipolar integrated circuits.

5 CA3256

FIGURE 8. AN 8-TO-1 VIDEO SWITCH AMPLIFIER USING TWO