Datasheet

LTC2470/LTC2472
10
24702fb
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applicaTions inForMaTion
Data Input Format
The data input word is 4 bits long and consists of two en-
able bits (EN1 and EN2) and two programming bits (SPD
and SLP) see Table 2. EN1 is applied to the first rising edge
of SCK after the conversion is complete. Programming is
enabled by setting EN1 = 1 and EN2 = 0.
Table 2. Input Data Format
BIT NAME FUNCTION
EN1 Should Be High (EN1 = 1) in Order to Enable Program Mode
EN2 Should Be Low (EN2 = 0) in Order to Enable Program Mode
SPD Low (SPD = 0, Default) for 208sps, High (SPD = 1) for
833sps Output Rate
SLP Low (SLP = 0, Default) for Nap Mode, High (SLP = 1)
for Sleep Mode Where Both Reference and Converter are
Powered Down
*SDI May Also Be Tied Directly to GND to Set Output Rate to 208sps or
V
DD
to Set Output Rate to 833sps. Sleep Mode is Disabled if SDI is Tied
to GND or V
DD
.
Table 1. LTC2470/LTC2472 Output Data Format
SINGLE ENDED INPUT V
IN
(LTC2470)
DIFFERENTIAL INPUT VOLTAGE
V
IN
+
– V
IN
–
(LTC2472)
D15
(MSB)
D14 D13 D12...D2 D1 D0
(LSB)
CORRESPONDING
DECIMAL VALUE
≥V
REF
≥V
REF
1 1 1 1 1 1 65535
V
REF
– 1LSB V
REF
– 1LSB 1 1 1 1 1 0 65534
0.75 • V
REF
0.5 • V
REF
1 1 0 0 0 0 49152
0.75 • V
REF
– 1LSB 0.5 • V
REF
– 1LSB 1 0 1 1 1 1 49151
0.5 • V
REF
0 1 0 0 0 0 0 32768
0.5 • V
REF
– 1LSB –1LSB 0 1 1 1 1 1 32767
0.25 • V
REF
–0.5 • V
REF
0 1 0 0 0 0 16384
0.25 • V
REF
– 1LSB –0.5 • V
REF
– 1LSB 0 0 1 1 1 1 16383
0 ≤ –V
REF
0 0 0 0 0 0 0
D
15
LSB
SDO
SCK
D
14
D
13
D
12
D
11
D
10
D
9
D
8
D
7
D
6
D
5
D
4
D
3
D
2
D
0
D
1
24702 F05
t
1
t
3
t
KQ
t
lSCK
t
hSCK
t
2
CS
MSB
SDI
EN2 SPD SLP
DON’T CARE
t
4
t
5
EN1
Figure 5. Data Input/Output Timing