Datasheet

20
LTC1854/LTC1855/LTC1856
185456fa
APPLICATIO S I FOR ATIO
WUUU
Figure 9. Nap Mode Operation for the LTC1856*
SGL/
DIFF
1
RD
SCK
SDI
Hi-Z
SDO
BUSY
CONVST
2 3 4 5 6 7 8 15 16
ODD/
SIGN
SELECT
1
SELECT
0
X X NAP = 1 SLEEP = 0 DON’T CARE
DON’T
CARE
B14 B13 B12B15 (MSB)
B11 B10 B9 B8
t
CONV
Hi-Z
NAP
t
ACQ
t
ACQ
SHIFT CONFIGURATION WORD IN
SGL/
DIFF
12345678 1516
ODD/
SIGN
SELECT
1
SELECT
0
X X NAP SLEEP DON’T CARE
B14 B13 B12B15 MSB
B11 B10 B9 B8
Hi-Z
SHIFT A/D RESULT OUT FROM PREVIOUS CONVERSION AND NEW CONFIGURATION WORD IN
18545 F09
B1 B0
B1 B0
Figure 11. Wake Up from Sleep Mode for the LTC1856*
Figure 10. Sleep Mode Operation for the LTC1856*
SGL/
DIFF
1
RD
SCK
SDI
SDO
BUSY
CONVST
2 3 4 5 6 7 8 15 16
ODD/
SIGN
SELECT
1
SELECT
0
X X NAP
SLEEP = 0
DON’T CARE
DON’T
CARE
B14 B13 B12B15 (MSB)
B11 B10 B9 B8
WAKE-UP
TIME
READY
t
CONV
SLEEP
SHIFT WAKE-UP CONFIGURATION WORD IN
SGL/
DIFF
12345678 1516
ODD/
SIGN
SELECT
1
SELECT
0
X X NAP SLEEP DON’T CARE
B14 B13 B12B15 (MSB)
B11 B10 B9 B8
A/D RESULT NOT VALID
SHIFT A/D RESULT OUT AND NEW CONFIGURATION WORD IN
t
CONV
18545 F11
B1 B0
B1 B0
*For the 12-bit LTC1854 and 14-bit LTC1855 the last four and two bits of the SDO will output zeros, respectively.
SGL/
DIFF
1
RD
SCK
SDI
SDO
BUSY
CONVST
2 3 4 5 6 7 8 15 16
ODD/
SIGN
SELECT
1
SELECT
0
X X NAP
SLEEP = 1
DON’T CARE
DON’T
CARE
B14 B13 B12B15 (MSB)
B11 B10 B9 B8
SHIFT SLEEP CONFIGURATION WORD IN
A/D RESULT FROM PREVIOUS CONVERSION
CONVST SHOULD STAY EITHER HIGH OR LOW IN SLEEP MODE
t
CONV
SLEEP
18545 F10
B1 B0