LTC2492 Linear Technology, LTC2492 Datasheet - Page 19

• Manufacturer Part Number: LTC2492
• Description: 24-Bit 2-/4-Channel ADC
• Manufacturer: Linear Technology

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APPLICATIONS INFORMATION
a new input word with EN = 1 (the fi rst three bits are 101)
and EN2 = 1 is shifted into the device.
Rejection Mode (FA, FB)
The LTC2492 includes a high accuracy on-chip oscillator
with no required external components. Coupled with an
integrated 4th order digital low pass fi lter, the LTC2492
rejects line frequency noise. In the default mode, the
LTC2492 simultaneously rejects 50Hz and 60Hz by at least
87dB. If more rejection is required, the LTC2492 can be
confi gured to reject 50Hz or 60Hz to better than 110dB.
Speed Mode (SPD)
Every conversion cycle, two conversions are combined to
remove the offset (default mode). This result is free from
offset and drift. In applications where the offset is not
critical, the auto-calibration feature can be disabled with
the benefi t of twice the output rate. While operating in the
2x mode (SPD = 1), the linearity and full-scale errors are
unchanged from the 1× mode performance. In both the
Table 4. Converter Confi guration
1
1
1
0
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
EN
0
1
0
1
1
1
1
1
1
1
1
1
1
SGL
X
X
X
X
X
X
X
X
X
X
X
X
X
ODD
X
X
X
X
X
X
X
X
X
X
X
X
X
A2
X
X
X
X
X
X
X
X
X
X
X
X
X
A1
X
X
X
X
X
X
X
X
X
X
X
X
X
A0
X
X
X
X
X
X
X
X
X
X
X
X
X
EN2
X
0
X
1
1
1
1
1
1
1
1
1
1
1× and 2× mode there is no latency. This enables input
steps or multiplexer changes to settle in a single conversion
cycle, easing system overhead and increasing the effective
conversion rate. During temperature measurements, the 1×
mode is always used independent of the value of SPD.
Temperature Sensor
The LTC2492 includes an integrated temperature sensor.
The temperature sensor is selected by setting IM = 1. The
digital output is proportional to the absolute temperature
of the device. This feature allows the converter to perform
cold junction compensation for external thermocouples or
continuously remove the temperature effects of external
sensors.
The internal temperature sensor output is 28mV at 27°C
(300°K), with a slope of 93.5μV/°C independent of V
(see Figures 4 and 5). Slope calibration is not required if
the reference voltage (V
a slope of 314 LSBs
IM
X
X
X
X
0
0
0
0
0
0
1
1
1
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
24
SPD
/°C. The temperature is calculated
X
X
X
0
0
0
1
1
1
X
X
X
X
REF
) is known. A 5V reference has
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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LTC2492
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REF