1. ADV7180 Fast Switching for Automotive applications ATV

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

3. 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.

4. 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.

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

6. 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.

7. 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

8. 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

9. 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.

10. 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

11. 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.

12. 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.