LTC1856 Linear Technology, LTC1856 Datasheet - Page 14

• Manufacturer Part Number: LTC1856
• Description: 100ksps ADC Converters
• Manufacturer: Linear Technology

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APPLICATIO S I FOR ATIO
LTC1854/LTC1855/LTC1856
LT1227: 140MHz video current feedback amplifier. 10mA
supply current. ±5V to ±15V supplies. Low noise and low
distortion.
LT1468/LT1469: Single and dual 90MHz, 16-bit accurate
op amp. Good AC/DC specs. ±5V to ±15V supplies.
LT1677: Single, low noise op amp. Rail-to-rail input and
output. Up to ±15V supplies.
14
COM
CH0
CH1
CH7
•
•
•
A
A
IN
IN
Figure 2. Analog Input Filtering
+
–
U
INPUT MUX
3000pF
AGND1
U
MUXOUT
CH0
CH1
MUXOUT
MUXOUT
ADC
ADC
Figure 1. LTC1854/LTC1855/LTC1856 Simplified Equivalent Circuit
•
•
•
•
–
+
–
18545
W
+
–
MUXOUT
F02
+
ADC
U
+
ADC
–
MUX ADDRESS
REFERENCE
V
2.5V
REF
+
–
8k
LT1792: Single, low noise JFET input op amp, ±5V
supplies.
LT1793: Single, low noise JFET input op amp, 10pA bias
current, ±5V supplies.
LT1881/LT1882: Dual and quad, 200pA bias current, rail-
to-rail output op amps. Up to ±15V supplies.
LT1844/LT1885: Dual and quad, 400pA bias current, rail-
to-rail output op amps. Up to ±15V supplies. Faster
response and settling time.
INTERNAL VOLTAGE REFERENCE
The LTC1854/LTC1855/LTC1856 have an on-chip, tem-
perature compensated, curvature corrected, bandgap ref-
erence, which is factory trimmed to 2.50V. The full-scale
range of the LTC1854/LTC1855/LTC1856 is equal to ±10V.
The output of the reference is connected to the input of a
gain of 1.6384x buffer through an 8k resistor (see Figure
3). The input to the buffer or the output of the reference is
SAMPLING ADC
12-/14-/16-BIT
INTERNAL
1.6384X
4.096V
CLOCK
REFCOMP
DATA OUT
AGND2
AV
CONTROL
DD
LOGIC
SERIAL I/O
AGND3
DV
DD
DGND
18545
F01
CONVST
SDI
BUSY
SCK
RD
OV
SDO
DD
185456fa