Datasheet

""#
SBAS255C − JUNE 2004 − REVISED APRIL 2009
www.ti.com
20
Changing Between Modes
Changing from cont to ncont mode occurs whenever T
INT
< t
6
. Figure 18 shows an example of this transition. In this
figure, cont mode is entered when the integration on side
A is completed before the m/r/az cycle on side B is
complete. The DDC114 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 ncont to cont mode occurs when T
INT
is
increased so that T
INT
is always ≥ t
6
as shown in Figure 19
(see 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 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