Datasheet LT6559 (Analog Devices) - 12

LT6559
TYPICAL APPLICATIONS YPBPR to RGB Conversion
Amplifi er B2 performs a weighted summation of all three inputs. The P Two LT6559s can be used to map the YP B signal is amplifi ed overall by: BPR “component” video into the RGB color space as shown in Figure 8. The −301 • 3.6 = 2(−0.34) Y input is properly terminated with 75Ω and buffered with 1.54k a gain of 2 by amplifi er A2. The PR input is terminated and buffered with a gain of 2.8 by amplifi er A1. The P The P B R signal is amplifi ed overall by: input is terminated and buffered with a gain of 3.6 by −301 amplifi er A3. • 2.8 = 2(−0.71) 590 Amplifi er B1 performs an equally weighted addition The Y signal is amplifi ed overall by: of amplifi ers A1 and A2 outputs, thereby producing 2(Y + 1.4P 1k 301 R), which generates the desired R signal at the • 1+ • 2 = 2 1 ( ) terminated load due to the voltage division by 2 caused by 1k + 698 590 || 1.54k the termination resistors. Amplifi er B3 forms the equally weighted addition of amplifi ers A2 and A3 outputs, thereby Therefore the amplifi er B2 output is: producing 2(Y + 1.8PB), which generates the desired B 2(Y – 0.34PB – 0.71PR) signal at the terminated load. which generates the desired G signal at the terminated load. The sync present on the Y input is reconstructed on all three R, G, and B outputs. 301Ω 301Ω – B1 75Ω 165Ω 301Ω 1/3 LT6559 R 1k + – R = Y + 1.40PR A1 1k G = Y – 0.34PB – 0.71 PR 1/3 LT6559 B = Y + 1.77PB PR + ALL RESISTORS 1% 75Ω VS = ±3V TO ±5V 590Ω 301Ω 301Ω 301Ω 1.54k – – B2 75Ω A2 1/3 LT6559 G 1/3 LT6559 698Ω + Y + 75Ω 1k 301Ω 301Ω 118Ω 301Ω – B3 75Ω – 1/3 LT6559 B A3 1k 1/3 LT6559 + PB + 1k 75Ω 6559 F08
Figure 8. YPBPR to RGB Conversion
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