LTC2494CUHF-PBF LINER [Linear Technology], LTC2494CUHF-PBF Datasheet - Page 19

• Manufacturer Part Number: LTC2494CUHF-PBF
• Description: 16-Bit 8-/16-Channel ?? ADC with PGA and Easy Drive Input Current Cancellation
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
GS1, GS0) are used to select the gain. The confi guration
remains valid until a new input word with EN = 1 (the fi rst
3 bits are 101) and EN2 = 1 is shifted into the device.
Rejection Mode (FA, FB)
The LTC2494 includes a high accuracy on-chip oscillator
with no required external components. Coupled with an
integrated 4th order digital low pass fi lter, the LTC2494
rejects line frequency noise. In the default mode, the
LTC2494 simultaneously rejects 50Hz and 60Hz by at least
87dB. If more rejection is required, the LTC2494 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
Table 4. Converter Confi guration
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
EN SGL ODD A2 A1 A0 EN2
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Channel
Input
Any
X
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
IM
X
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
Rejection
FA
X
X
0
0
1
1
0
0
1
1
Mode
Any
FB
X
X
0
1
0
1
0
1
0
1
Speed
SPD
Any
X
X
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
X
X
X
X
GS2 GS1 GS0
2x mode (SPD = 1), the linearity and full-scale errors are
unchanged from the 1x mode performance. In both the 1x
and 2x 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 1x
mode is always used independent of the value of SPD.
GAIN (GS2, GS1, GS0)
The input referred gain of the LTC2494 is adjustable
from 1 to 256 (see Tables 5a and 5b). With a gain of 1,
the differential input range is ±V
mode input range is rail-to-rail. As the gain is increased,
the differential input range is reduced to ±0.5 • V
but the common mode input range remains rail-to-rail.
As the differential gain is increased, low level voltages
are digitized with greater resolution. At a gain of 256, the
LTC2494 digitizes an input signal range of ±9.76mV with
over 16,000 counts.
X
X
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
X
X
X
X
Gain
Any
X
X
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
X
X
X
X
X
X
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
X
X
X
X
Temperature Input, Simultaneous 50Hz/60Hz Rejection
External Input, Simultaneous 50Hz/60Hz Rejection
External Input, Gain = 128, Autocalibration
External Input, Gain = 264, Autocalibration
External Input, Gain = 16, Autocalibration
External Input, Gain = 32, Autocalibration
External Input, Gain = 64, Autocalibration
External Input, Gain = 1, Autocalibration
External Input, Gain = 4, Autocalibration
External Input, Gain = 8, Autocalibration
External Input, Gain = 128, 2x Speed
External Input, Gain = 16, 2x Speed
External Input, Gain = 32, 2x Speed
External Input, Gain = 64, 2x Speed
Temperature Input, 50Hz Rejection
Temperature Input, 60Hz Rejection
External Input, Gain = 1, 2x Speed
External Input, Gain = 2, 2x Speed
External Input, Gain = 4, 2x Speed
External Input, Gain = 8, 2x Speed
CONVERTER CONFIGURATION
External Input, 50Hz Rejection
External Input, 60Hz Rejection
Reserved, Do Not Use
Reserved, Do Not Use
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REF
/2 and the common
LTC2494
REF
19
/Gain
2494fb