LTC1604ACG#PBF Linear Technology, LTC1604ACG#PBF Datasheet - Page 13

• Manufacturer Part Number: LTC1604ACG#PBF
• Description: IC A/D CONV 16BIT SAMPLNG 36SSOP
• Manufacturer: Linear Technology

Specifications of LTC1604ACG#PBF

• Number Of Bits: 16
• Sampling Rate (per Second): 333k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 350mW
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 36-SSOP (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Input Range
The 2.5V input range of the LTC1604 is optimized for low
noise and low distortion. Most op amps also perform well
over this same range, allowing direct coupling to the
analog inputs and eliminating the need for special transla-
tion circuitry.
Some applications may require other input ranges. The
LTC1604 differential inputs and reference circuitry can
accommodate other input ranges often with little or no
additional circuitry. The following sections describe the
reference and input circuitry and how they affect the input
range.
Internal Reference
The LTC1604 has an on-chip, temperature compensated,
curvature corrected, bandgap reference that is factory
trimmed to 2.500V. It is connected internally to a reference
amplifier and is available at V
A 7.5k resistor is in series with the output so that it can be
easily overdriven by an external reference or other
circuitry (see Figure 12b). The reference amplifier gains
the voltage at the V
internal reference voltage. This provides buffering
between the V
The reference amplifier compensation pin (REFCOMP, Pin
4) must be bypassed with a capacitor to ground. The
reference amplifier is stable with capacitors of 22 F or
greater. For the best noise performance a 47 F ceramic or
47 F tantalum in parallel with a 0.1 F ceramic is recom-
mended.
APPLICATIONS
ANALOG INPUT
REF
Figure 11. RC Input Filter
pin and the high speed capacitive DAC.
3000pF
REF
U
100
47 F
pin by 1.75 to create the required
INFORMATION
U
REF
1
2
3
4
5
(Pin 3) (see Figure 12a).
A
A
V
REFCOMP
AGND
IN
IN
REF
+
–
W
LTC1604
1604 F11
U
The V
shown in Figure 13. This is useful in applications where the
peak input signal amplitude may vary. The input span of
the ADC can then be adjusted to match the peak input
signal, maximizing the signal-to-noise ratio. The filtering
of the internal LTC1604 reference amplifier will limit
the bandwidth and settling time of this circuit. A settling
time of 20ms should be allowed for after a reference
adjustment.
Differential Inputs
The LTC1604 has a unique differential sample-and-hold
circuit that allows rail-to-rail inputs. The ADC will always
convert the difference of A
common mode voltage (see Figure 15a). The common
mode rejection holds up to extremely high frequencies
(see Figure 14a). The only requirement is that both inputs
Figure 12b. Using the LT1019-2.5 as an External Reference
4.375V
REF
2.500V
pin can be driven with a DAC or other means
47 F
Figure 12a. LTC1604 Reference Circuit
LT1019A-2.5
3
4
5
V
5V
V
REFCOMP
AGND
IN
REF
V
OUT
+
10 F
ANALOG
16k
R3
INPUT
REFERENCE
IN
12k
R2
+
AMP
– A
0.1 F
IN
1
2
3
4
5
–
A
A
V
REFCOMP
AGND
IN
IN
REF
independent of the
7.5k
+
–
R1
LTC1604
LTC1604
REFERENCE
BANDGAP
LTC1604
1604 F12b
1604 F12a
13