Low Cost RGB to NTSC/PAL Encoder a with Luma Trap Port AD725 FEATURES PRODUCT DESCRIPTION Composite Video Output: Both NTSC and PAL The AD725 is a very low cost general purpose RGB to NTSC/ Chrominance and Luminance (S-Video) Outputs PAL encoder that converts red, green and blue color compo- Luma Trap Port to Eliminate Cross Color Artifacts nent signals into their corresponding luminance (baseband TTL Logic Levels amplitude) and chrominance (subcarrier amplitude and phase) Integrated Delay Line and Auto-Tuned Filters signals in accordance with either NTSC or PAL standards. Drives 75 V Reverse-Terminated Loads These two outputs are also combined on-chip to provide a Low Power +5 V Operation composite video output. All three outputs are available sepa- Power-Down to <1 mA rately at voltages of twice the standard signal levels as re- Very Low Cost quired for driving 75 , reverse-terminated cables. The AD725 features a luminance trap (YTRAP) pin that pro- APPLICATIONS vides a means of reducing cross color generated by subcarrier RGB/VGA to NTSC/PAL Encoding frequency components found in the luminance signal. For por- Personal Computers/Network Computers table or other power-sensitive applications, the device can be Video Games powered down to less than 1 A of current consumption. All Video Conference Cameras logic levels are TTL compatible thus supporting the logic re- Digital Still Cameras quirements of 3 V CMOS systems. The AD725 is packaged in a low cost 16-lead SOIC and oper- ates from a +5 V supply. FUNCTIONAL BLOCK DIAGRAM NTSC/PAL CSYNC HSYNC SYNC XNOR SEPARATOR VSYNC CSYNC BURST NTSC/PAL 4FSC 4FSC CLOCK FSC 908C/2708C FSC 908C 61808C QUADRATURE 4FSC (PAL ONLY) +4 FSC 08C DECODER CLOCK AT 8FSC CSYNC 2-POLE 3-POLE SAMPLED- Y DC LUMINANCE RED LP PRE- DATA LP POST- X2 OUTPUT CLAMP DELAY LINE FILTER FILTER LUMINANCE TRAP COMPOSITE U NTSC/PAL RGB-TO-YUV U S X2 4-POLE OUTPUT DC GREEN ENCODING LPF CLAMP CLAMP MATRIX BALANCED 4-POLE CHROMINANCE X2 OUTPUT MODULATORS LPF V V DC 4-POLE BLUE CLAMP CLAMP LPF BURST REV. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or Tel: 781/329-4700 World Wide Web Site: (Unless otherwise noted, V = +5, T = +258C, using 4FSC synchronous clock. All loads are S A 150 V 6 5% at the IC pins. Outputs are measured at the 75 V reverse terminated load.) AD725SPECIFICATIONS Parameter Conditions Min Typ Max Units SIGNAL INPUTS (RIN, GIN, BIN) Input Amplitude Full Scale 714 mV p-p 1 Black Level 0.8 V 2 Input Resistance RIN, GIN, BIN 1 M Input Capacitance 5pF LOGIC INPUTS (HSYNC, VSYNC, 4FSC, CE, STND) TTL Logic Levels Logic Low Input Voltage 1V Logic High Input Voltage 2V Logic Low Input Current (DC) 1 A Logic High Input Current (DC) 1 A 3 VIDEO OUTPUTS Luminance (LUMA) Bandwidth, 3 dB NTSC 4.4 MHz PAL 5.2 MHz Gain Error 7 2 +7 % Nonlinearity max p-p 0.3 % Sync Level NTSC 252 279 310 mV PAL 264 291 325 mV DC Black Level 1.3 V Luminance Trap (YTRAP) Output Resistance 1.0 k DC Black Level 1.0 V Chrominance (CRMA) Bandwidth, 3 dB NTSC 1.2 MHz PAL 1.5 MHz Color Burst Amplitude NTSC 206 255 305 mV p-p PAL 221 291 362 mV p-p Color Burst Width NTSC 2.51 s PAL 2.28 s 4 Chroma Level Error 4 % 5 Chroma Phase Error 3 Degrees DC Black Level 2.0 V Chroma Feedthrough R, G, B = 0 15 40 mV p-p Composite (COMP) Absolute Gain Error With Respect to Luma 5 1 +3 % Differential Gain With Respect to Chroma 0.5 % Differential Phase With Respect to Chroma 1.5 Degrees DC Black Level 1.4 V Chroma/Luma Time Alignment S-Video 20 ns POWER SUPPLIES Recommended Supply Range Single Supply +4.75 +5.25 V Quiescent CurrentEncode Mode 30 36 mA Quiescent CurrentPower Down <1 A NOTES 1 R, G, and B signals are inputted via an external ac coupling capacitor. 2 Except during dc restore period (back porch clamp). 3 All outputs measured at a 75 reverse-terminated load ac voltages at the IC output pins are twice those specified here. 4 Difference between ideal and actual color bar subcarrier amplitudes. 5 Difference between ideal and actual color bar subcarrier phases. Specifications are subject to change without notice. 2 REV. 0