Datasheet
LTC6360
11
6360f
operaTion
The LTC6360 is a low noise amplifier suitable for driving
single-ended high performance successive approximation
register (SAR) ADCs. The LTC6360 uses a single ampli-
fier with negative charge pump topology as shown in the
Block Diagram.
The output can swing from –0.48V to 4.91V. The ampli-
fier is designed to drive a series 10Ω resistor and 330pF
capacitor filter network to ground, although larger load
capacitances can be driven.
An on-chip low noise charge pump generates a small
negative voltage (typically –0.6V) at the CPO pin. This
negative voltage is normally connected to the amplifier’s
output stage via the CPI pin, allowing the output to swing
to true zero on a single 5V supply. Compared to typical
rail-to-rail output amplifiers that can only swing to within
a few hundred millivolts of ground, the LTC6360 provides
improved linearity and increased functionality for applica-
tions that benefit from a true zero output swing.
The LTC6360 features a low noise amplifier that can
support a signal-to-noise ratio of 110dB over a 3MHz
noise bandwidth.
Basic Connections
Shown in Figure 2 is a typical application for the LTC6360
as a unity gain driver. The amplifier’s two inputs (+IN and
–IN) can accommodate a voltage range of 0V to 4.25V on
a single 5V rail. This provides a simple interface for 5V
ADCs with a 4.096V full-scale range.
Noninverting gain (shown in Figure 3) and inverting gain
(shown in Figure 4) configurations are also possible. For
best DC precision, R
S
should be made equal to the paral-
lel combination of R
F
and R
G
. R
S
can be bypassed with a
capacitor to reduce its noise contribution.
Figure 2. Unity Gain Driver.
Figure 3. Noninverting Gain Configuration.
Figure 4. Inverting Gain Configuration
5V
V
IN
0V TO 4V
10Ω
0.1µF
5V
6360 F02
CPO
V
DD
GND
LTC6360
OUT–IN
V
CC
V
OUT
CPISHDN+IN
–
+
CHARGE
PUMP
0.1µF 10µF
330pF
+
–
4V
0V
V
IN
4V
0V
1µF
5V
V
IN
R
S
0.1µF
5V
6360 F03
CPO
V
DD
GND
LTC6360
OUT–IN
V
CC
V
OUT
R
F
C
F
R
G
CPISHDN+IN
–
+
CHARGE
PUMP
0.1µF 10µF
+
–
1µF
R
FILT
C
FILT
C
S
5V
R
S
0.1µF
5V
6360 F04
CPO
V
DD
GND
LTC6360
OUT–IN
V
CC
V
OUT
R
F
R
G
V
IN
CPISHDN+IN
–
+
CHARGE
PUMP
0.1µF 10µF
+
–
C
F
1µF
R
FILT
C
FILT