Chapter 4

Analog Input

ai/SampleClock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ai/ConvertClock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 1 2 3

 

 

0 1 2 3

 

 

Channel Measured

0 1 2 3

 

 

 

 

 

 

 

 

 

 

 

Sample #1

 

 

Sample #2

 

 

Sample #3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• Properly Matched Sample Clock and Convert Clock

Figure 4-13.ai/SampleClock and ai/ConvertClock Properly Matched

It is also possible to use a single external signal to drive both ai/SampleClock and ai/ConvertClock at the same time. In this mode, each tick of the external clock will cause a conversion on the ADC. Figure 4-14shows this timing relationship.

ai/SampleClock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ai/ConvertClock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 1 2 3 0 1 2 3

 

0 1 …

Channel Measured

 

 

 

Sample #1 Sample #2

Sample #3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• One External Signal Driving Both Clocks

Figure 4-14.Single External Signal Driving ai/SampleClock and ai/ConvertClock

Simultaneously

AI Convert Clock Timebase Signal

The AI Convert Clock Timebase (ai/ConvertClockTimebase) signal is divided down to provide on of the possible sources for ai/ConvertClock. Use one of the following signals as the source of ai/ConvertClockTimebase:

•ai/SampleClockTimebase

•20 MHz Timebase

ai/ConvertClockTimebase is not available as an output on the I/O connector.