Datasheet

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SBAS325B − JUNE 2004 − REVISED APRIL 2009
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20
Changing Between Modes
Changing from the cont to ncont mode occurs whenever
T
INT
< t
6
. Figure 18 shows an example of this transition.
In this figure, the cont mode is entered when the integration
on side A is completed before the m/r/az cycle on side B
is complete. The DDC118 completes the measurement on
sides B and A during states 8 and 7 with the input signal
shorted to ground. Ncont integration begins with state 6.
Changing from the ncont to cont mode occurs when T
INT
is increased so that T
INT
is always ≥ t
6
, as shown in
Figure 19 (see also Figure 14 and Table 8, page 18). With
a longer T
INT
, the m/r/az cycle has enough time to finish
before the next integration begins and continuous
integration of the input signal is possible. For the special
case of the very first integration when changing to the cont
mode, T
INT
can be < t
6
. This is allowed because there is
no simultaneous
m/r/az cycle on the side B during state
3—there is no need to wait for it to finish before ending the
integration on side A.
CONV
8745
Continuous Non−Continuous
5 65
State
Integration
Status
m/r/az
Status
mbsy
m/r/az B m/r/az A m/r/az B m/r/az A m/r/az B
Integrate A Integrate B Int AInt A Int B
Figure 18. Changing from Continuous Mode to Non-Continuous Mode
CONV
4214
Non−Continuous Continuous
33
State
mbsy
m/r/az
Status
Integration
Status
m/r/az A m/r/az B m/r/az A
Int BInt A Integrate A Integrate B
Figure 19. Changing from Non-Continuous Mode to Continuous Mode