ADV7180 Fast Switching for Automotive applications ATV

Introduction What is fast switching Why is fast switching required? ADI’s solution Testing completed Results Conclusion

Why is Fast Switching required in Automotive applications On December 3, 2010,  The National Highway Traffic Safety Administration (NHTSA) has proposed a new safety regulation, which will require that all cars have back-up cameras by 2014 (phased approach). NHTSA proposes a 2.0-second maximum image response time after the vehicle’s transmission is shifted into reverse Consumers expections to switch seemlessly between analog video sources in the blink of an eye (200 msec or less) also mandates the requirement for fast switching.

Fast Switching ADI decoders have the ability to switch very quickly between different inputs. Significant testing of the switching time for the ADV7180 has been carried out. Shown in the next slides are results from this testing and the test setup used.

Setup Setup Used AIN2 FIELD SCL(TRIGGER) AIN1 AIN2 SDA SCL GND ADSR Analog Devices' Signal Recorded (Customer's Grab)

ADI analysis: ADI monitored the FIELD pin output to determine when correct lock has been achieved. Once a stable FIELD signal was observed the part was deemed to be in lock. Test results showed fast acquisition within 250ms. Testing using real life customer grabs of camera inputs was also carried out.

ADI analysis: Fast Clamping delivering fast video acquisition Pink = AIN2 Voltage Clamp Settling Time once clamp reacts Blue = SCLK Green = Field I2C writes done Clamp Settling Time

Comparison of Fast Switching and Standard script for different input cases Fast Switch Script Standard Script plus TRAQ write CASE 1 141ms 415ms CASE 2 137ms 319ms CASE 3 190ms 467ms CASE 4 180ms 471ms

Description of Autodetect operation In Standard operating mode the decoder uses the H-SYNC PLL and V-SYNC processors. Using these processors allows the following: The decoder to lock more accurately to non-standard and poor time based sources. The decoder to maintain lock to these signals even when the time base is temporarily broken or corrupted. As part of the autodetect process a computed H-SYNC falling edge generated reference is used (see diagram). The reference is a start time from which windows of the active video signal are sampled and used in the autodetect process.

Block Diagram HSYNC PLL Input Sync Regenerated Sync Out Falling edge reference HSYNC PLL Regenerated Sync Out Blank gate begin Burst gate begin Blank measurement window Burst measurement window

Fast Switching Script Using the fast switching script disables blocks that provide robustness for non-standard signals but allow very fast acquisition to nominal signals. As part of this configuration the H-SYNC PLL is disabled. Doing this also means that the accuracy of the H-SYNC reference will change and hence autodetection between some standards becomes less reliable.

Conclusion Using the Fast switching script allows for quick signal lock times. However: Fast switching scripts can only be used for high quality nominal input signals. When using the fast switching script the standard should be forced or the autodetection limited. We do NOT advise any deviation from the advised scripts, i.e. the fast switching script and the Standard ADI script. Deviation from these may introduce uncertainty.