LTC1403IMSE Ver la hoja de datos (PDF) - Linear Technology
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LTC1403IMSE Datasheet PDF : 20 Pages
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APPLICATIO S I FOR ATIO
LTC1403/LTC1403A
CMRR vs Frequency
0
–20
–40
–60
–80
–100
–120
100 1k 10k 100k 1M 10M 100M
FREQUENCY (Hz)
1403A F03
Figure 3
LTC1403/LTC1403A Transfer
Characteristic
111...111
111...110
111...101
000...010
000...001
000...000
0
FS – 1LSB
INPUT VOLTAGE (V)
1403A F05
Figure 4
INPUT SPAN VERSUS REFERENCE VOLTAGE
The differential input range has a unipolar voltage span
that equals the difference between the voltage at the
reference buffer output VREF at Pin 3, and the voltage at the
ground (Exposed Pad Ground). The differential input
range of the ADC is 0V to 2.5V when using the internal
reference. The internal ADC is referenced to these two
nodes. This relationship also holds true with an external
reference.
DIFFERENTIAL INPUTS
The LTC1403/LTC1403A has a unique differential sample-
and-hold circuit that allows inputs from ground to VDD.
The ADC will always convert the unipolar difference of
AIN+ – AIN–, independent of the common mode voltage at
the inputs. The common mode rejection holds up at
extremely high frequencies, see Figure 3. The only require-
ment is that both inputs not go below ground or exceed
VDD. Integral nonlinearity errors (INL) and differential
nonlinearity errors (DNL) are largely independent of the
common mode voltage. However, the offset error will
vary. The change in offset error is typically less than 0.1%
of the common mode voltage.
Figure 4 shows the ideal input/output characteristics for
the LTC1403/LTC1403A. The code transitions occur mid-
way between successive integer LSB values (i.e., 0.5LSB,
1.5LSB, 2.5LSB, FS – 1.5LSB). The output code is natural
binary with 1LSB = 2.5V/16384 = 153µV for the LTC1403A,
and 1LSB = 2.5V/4096 = 610µV for the LTC1403. The
LTC1403A has 1LSB RMS of random white noise.
1403af
11
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