Datasheet

LTC2413
14
sn2413 2413fs
on the rising edge of the 32nd SCK pulse. On the falling
edge of the 32nd SCK pulse, SDO goes HIGH indicating the
initiation of a new conversion cycle. This bit serves as EOC
(Bit 31) for the next conversion cycle. Table 2 summarizes
the output data format.
As long as the voltage on the IN
+
and IN
–
pins is maintained
within the –0.3V to (V
CC
+ 0.3V) absolute maximum
operating range, a conversion result is generated for any
differential input voltage V
IN
from –FS = –0.5 • V
REF
to
+FS = 0.5 • V
REF
. For differential input voltages greater than
+FS, the conversion result is clamped to the value corre-
sponding to the +FS + 1LSB. For differential input voltages
below –FS, the conversion result is clamped to the value
corresponding to –FS – 1LSB.
Simultaneous Frequency Rejection
The LTC2413 internal oscillator provides better than 87dB
normal mode rejection over the range of 49Hz to 61.2Hz as
shown in Figure 4. For this simultaneous 50Hz/60Hz
rejection, F
O
should be connected to GND.
When a fundamental rejection frequency different from
the range 49Hz to 61.2Hz is required or when the converter
must be sychronized with an outside source, the LTC2413
can operate with an external conversion clock. The conveter
automatically detects the presence of an external clock
signal at the F
O
pin and turns off the internal oscillator. The
frequency f
EOSC
of the external signal must be at least
2560Hz to be detected. The external clock signal duty cycle
is not significant as long as the minimum and maximum
specifications for the high and low periods, t
HEO
and t
LEO
,
are observed.
Table 2. LTC2413 Output Data Format
Differential Input Voltage Bit 31 Bit 30 Bit 29 Bit 28 Bit 27 Bit 26 Bit 25 … Bit 0
V
IN
* EOC DMY SIG MSB
V
IN
* ≥ 0.5 • V
REF
** 00110 0 0…0
0.5 • V
REF
** – 1LSB 00101 1 1…1
0.25 • V
REF
** 00101 0 0…0
0.25 • V
REF
** – 1LSB 00100 1 1…1
0 00100 0 0…0
–1LSB 0 0011 1 1…1
–0.25 • V
REF
** 00011 0 0…0
–0.25 • V
REF
** – 1LSB 00010 1 1…1
–0.5 • V
REF
** 00010 0 0…0
V
IN
* < –0.5 • V
REF
** 00001 1 1…1
*The differential input voltage V
IN
= IN
+
– IN
–
.
**The differential reference voltage V
REF
= REF
+
– REF
–
.
Figure 3. Output Data Timing
APPLICATIO S I FOR ATIO
WUU
U
MSBSIG“0”
1 2 3 4 5 262732
BIT 0BIT 27 BIT 5
LSB
24
BIT 28BIT 29BIT 30
SDO
SCK
CS
EOC
BIT 31
SLEEP DATA OUTPUT CONVERSION
2413 F03
Hi-Z