LTC1400CS8 Linear Technology, LTC1400CS8 Datasheet - Page 10

• Manufacturer Part Number: LTC1400CS8
• Description: IC A/D CONV 12BIT W/SHTDN 8-SOIC
• Manufacturer: Linear Technology

Specifications of LTC1400CS8

• Number Of Bits: 12
• Sampling Rate (per Second): 400k
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 160mW
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC1400
trimmed to 2.42V. It is internally connected to the DAC
and is available at Pin 3 to provide up to 1mA of current to
an external load. For minimum code transition noise, the
reference output should be decoupled with a capacitor to
filter wideband noise from the reference (10μF tantalum in
parallel with a 0.1μF ceramic). The V
with a DAC or other means to provide input span adjust-
ment in bipolar mode. The V
least 2.45V to prevent conflict with the internal reference.
The reference should not be driven to more than 5V.
Figure 6 shows an LT1360 op amp driving the reference
pin. Figure 7 shows a typical reference, the LT1019A-5
connected to the LTC1400. This will provide an improved
drift (equal to the maximum 5ppm/°C of the LT1019A-
5) and a ±4.231V full scale. If V
2.42V, the REFRDY bit in the serial data output will be
forced to low.
10
±0.846 • V
INPUT RANGE ±4.231V
INPUT RANGE
(= ±0.846 • V
Figure 6. Driving the V
REF(OUT)
Figure 7. Supplying a 5V Reference Voltage
to the LTC1400 with the LT1019A-5
REF
)
+
–
LT1360
U
LT1019A-5
GND
10V
V
IN
V
U
REF
OUT
V
REF(OUT)
REF
with the LT1360 Op Amp
pin must be driven to at
REF
≥ 2.45V
W
3Ω
10µF
3Ω
REF
is forced lower than
10µF
pin can be driven
A
V
GND
A
V
GND
REF
IN
IN
REF
U
LTC1400
LTC1400
–5V
–5V
V
V
5V
V
V
5V
CC
SS
CC
SS
1400 F07
1400 F06
Unipolar/Bipolar Operation and Adjustment
Figure 8 shows the ideal input/output characteristics for
the LTC1400. The code transitions occur midway between
successive integer LSB values (i.e., 0.5LSB, 1.5LSB,
2.5LSB, … FS – 1.5LSB). The output code is straight
binary with 1LSB = 4.096V/4096 = 1mV. Figure 9 shows
the input/output transfer characteristics for the bipolar
mode in two’s complement format.
Unipolar Offset and Full-Scale Error Adjustments
In applications where absolute accuracy is important,
offset and full-scale errors can be adjusted to zero. Figure
10a shows the extra components required for full-scale
Figure 8. LTC1400 Unipolar Transfer Characteristics
Figure 9. LTC1400 Bipolar Transfer Characteristics
111...111
111...110
111...101
111...100
000...011
000...010
000...001
000...000
011...111
011...110
000...001
000...000
111...111
111...110
100...001
100...000
0V
–FS/2
UNIPOLAR
ZERO
1LSB = FS
LSB
1
4096
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
BIPOLAR
LSB
–1
ZERO
0V
LSB
1
FS/2 – 1LSB
FS – 1LSB
11400 F09
1400 F08
1400fa