DDC114IRTCT Datasheet, PDF (20/35 Pages) Texas Instruments – Quad Current Input, 20-Bit Analog-To-Digital Converter

DDC114
SBAS255C − JUNE 2004 − REVISED APRIL 2009
Changing Between Modes
Changing from cont to ncont mode occurs whenever T_INT
< t₆. 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.
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Changing from ncont to cont mode occurs when T_INT is
increased so that T_INT is always ≥ t₆ 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 < t₆.
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
State
5
Integration
Status
Integrate A
m/r/az
Status
m/r/az B
mbsy
4
5
Continuous
Integrate B
Int A
8
Non−Continuous
76
5
Int B Int A
m/r/az A
m/r/az B
m/r/az A
m/r/az B
Figure 18. Changing from Continuous Mode to Non-Continuous Mode
CONV
State
Integration
Status
m/r/az
Status
3
4
Int A Int B
1
2
Non−Continuous
m/r/az A
m/r/az B
mbsy
3
Continuous
Integrate A
4
Integrate B
m/r/az A
Figure 19. Changing from Non-Continuous Mode to Continuous Mode
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