Datasheet

LTC2486
18
2486fd
Rejection Mode (FA, FB)
The LTC2486 includes a high accuracy on-chip oscillator
with no required external components. Coupled with an
integrated 4th order digital low pass fi lter, the LTC2486 re-
jects line frequency noise. In the default mode, the LTC2486
simultaneously rejects 50Hz and 60Hz by at least 87dB. If
more rejection is required, the LTC2486 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 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 LTC2486 is adjustable
from 1 to 256 (see Tables 5a and 5b). With a gain of 1,
the differential input range is ±V
REF
/2 and the common
mode input range is rail-to-rail. As the gain is increased,
the differential input range is reduced to ±0.5 • V
REF
/Gain
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 LTC2486 digitizes an input signal range of ±9.76mV
(V
REF
= 5V) with over 16,000 counts.
APPLICATIONS INFORMATION
Table 4. Converter Confi guration
1 0 EN SGL ODD A2 A1 A0 EN2 IM FA FB SPD GS2 GS1 GS0 CONVERTER CONFIGURATION
100
Any
Input
Channel
X X X X X X X X Keep Previous
1 0 1 0 X X X X X X X Keep Previous
101 1 0
Any
Rejection
Mode
0 0 0 0 External Input, Gain = 1, Autocalibration
1 0 1 1 0 0 0 0 1 External Input, Gain = 4, Autocalibration
1 0 1 1 0 0 0 1 0 External Input, Gain = 8, Autocalibration
1 0 1 1 0 0 0 1 1 External Input, Gain = 16, Autocalibration
1 0 1 1 0 0 1 0 0 External Input, Gain = 32, Autocalibration
1 0 1 1 0 0 1 0 1 External Input, Gain = 64, Autocalibration
1 0 1 1 0 0 1 1 0 External Input, Gain = 128, Autocalibration
1 0 1 1 0 0 1 1 1 External Input, Gain = 264, Autocalibration
1 0 1 1 0 1 0 0 0 External Input, Gain = 1, 2x Speed
1 0 1 1 0 1 0 0 1 External Input, Gain = 2, 2x Speed
1 0 1 1 0 1 0 1 0 External Input, Gain = 4, 2x Speed
1 0 1 1 0 1 0 1 1 External Input, Gain = 8, 2x Speed
1 0 1 1 0 1 1 0 0 External Input, Gain = 16, 2x Speed
1 0 1 1 0 1 1 0 1 External Input, Gain = 32, 2x Speed
1 0 1 1 0 1 1 1 0 External Input, Gain = 64, 2x Speed
1 0 1 1 0 1 1 1 1 External Input, Gain = 128, 2x Speed
101 1000
Any
Speed
Any
Gain
External Input, Simultaneous 50Hz/60Hz Rejection
101 1001 External Input, 50Hz Rejection
101 1010 External Input, 60Hz Rejection
101 1011 Reserved, Do Not Use
101 1100 X XXXTemperature Input, Simultaneous 50Hz/60Hz Rejection
101 1101 X XXX Temperature Input, 50Hz Rejection
1 0 1 1 1 1 0 X X X X Temperature Input, 60Hz Rejection
1 0 1 1 1 1 1 X X X X Reserved, Do Not Use