ltc2493 Linear Technology Corporation, ltc2493 Datasheet - Page 18

• Manufacturer Part Number: ltc2493
• Description: 24-bit 2-/4-channel Delta Sigma Adc With Easy Drive Input Current Cancellation And I2c Interface
• Manufacturer: Linear Technology Corporation

LTC2493
applicaTions inForMaTion
The second set of configuration data can be loaded into
the device by setting EN2 = 1 (see Table 4). The first bit
(IM) is used to select the internal temperature sensor. If
IM = 1, the following conversion will be performed on
the internal temperature sensor rather than the selected
input channel. The next two bits (FA and FB) are used to
Table 3 Channel Selection
*Default at power up

SGL
*0
0
0
0
1
1
1
1
Table 4. Converter Configuration
1
1
1
0
1
1
1
1
1
1
1
1
1
1
ODD/
SIGN
0
0
1
1
0
0
1
1
MUX ADDRESS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
A2
0
0
0
0
0
0
0
0
EN
A1
0
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
SGL
A0
0
1
0
1
0
1
0
1
X
X
X
X
X
X
X
X
X
X
X
X
X
IN
IN
IN
ODD
0
+
–
+
X
X
X
X
X
X
X
X
X
X
X
X
X
CHANNEL SELECTION
IN
IN
IN
1
–
+
+
A2
X
X
X
X
X
X
X
X
X
X
X
X
X
IN
IN
IN
2
+
–
+
A1
X
X
X
X
X
X
X
X
X
X
X
X
X
IN
IN
IN
3
–
+
+
A0
X
X
X
X
X
X
X
X
X
X
X
X
X
COM
IN
IN
IN
IN
–
–
–
–
EN2
X
X
0
1
1
1
1
1
1
1
1
1
1
set the rejection frequency. The final bit (SPD) is used to
select either the 1x output rate if SPD = 0 (auto-calibration
is enabled and the offset is continuously calibrated and
removed from the final conversion result) or the 2x output
rate if SPD = 1 (offset calibration disabled, multiplexing
output rates up to 15Hz with no latency). When IM = 1
(temperature measurement) SPD will be ignored and the
device will operate in 1x mode.
The configuration remains valid until a new input word with
EN = 1 (the first three bits are 101 for the first word) and EN2
= 1 (for the second write byte) is shifted into the device.
Rejection Mode (FA, FB)
The LTC2493 includes a high accuracy on-chip oscillator
with no required external components. Coupled with an
integrated fourth order digital low pass filter, the LTC2493
rejects line frequency noise. In the default mode, the
LTC2493 simultaneously rejects 50Hz and 60Hz by at least
87dB. If more rejection is required, the LTC2493 can be
configured to reject 50Hz or 60Hz to better than 110dB.
IM
X
X
X
0
0
0
0
0
0
1
1
1
X
FA
X
X
X
0
0
1
0
0
1
0
0
1
1
FB
X
X
X
0
1
0
0
1
0
0
1
0
1
SPD
X
X
X
X
X
X
X
0
0
0
1
1
1
CONVERTER CONFIGURATION
External Input (See Table 3)
External Input (See Table 3)
External Input (See Table 3)
External Input (See Table 3)
External Input (See Table 3)
External Input (See Table 3)
50Hz/60Hz Rejection, 1x
50Hz/60Hz Rejection, 2x
50Hz/60Hz Rejection, 1x
Reserved, Do Not Use
Measure Temperature
Measure Temperature
Measure Temperature
50Hz Rejection, 1x
60Hz Rejection, 1x
50Hz Rejection, 2x
60Hz Rejection, 2x
50Hz Rejection, 1x
60Hz Rejection, 1x
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