LTC8821, LTC8822, LTC8824
P-1
General Description
The LTC882x family of single-, dual-, and quad- channel amplifiers features a
maximized ratio of gain bandwidth (GBW) to supply current and is ideal for batterypowered applications such as wearables, handsets, tablets, and portable medical
devices. Featuring rail-to-rail input and output swings, a wide bandwidth of 500-kHz
combined with ultra-low supply current (typical 6.6 µA at VS=5.5V per amplifier) and low
noise (6 μVP-P at 0.1 to 10 Hz) , the LTC882x family is an excellent choice for precision or
general-purpose, low-current, low-voltage, battery-powered applications. The low input
bias current supports these amplifiers to be used in applications with mega-ohm source
impedances.
The robust design of the LTC882x operational amplifiers provides ease-of-use to the
circuit designer: integrated RF/EMI rejection filter, no phase reversal in overdrive
conditions, and high electro-static discharge (ESD) protection (5-kV HBM). The LTC882x
amplifiers are optimized for operation at voltages as low as +1.8 V (±0.9 V) and up to
+5.5 V (±2.75 V).
The LTC8821 (single) is available in both SOT23-5L and SC70-5L packages. The LTC8822
(dual) is offered in DFN-8L, SOIC-8L and MSOP-8L packages. The quad-channel
LTC8824 is offered in both SOIC-14L and TSSOP-14L packages. All of the devices are
specified over the extended temperature range of −40 ℃ to +125 ℃.
Features and Benefits
500 kHz GBW
Ultra-Low 6.6 μA Supply Current (at 5.5V Supply, Per Amplifier)
Low Input Offset Voltage: 0.5 mV
Low Noise: 6 μVP-P at 0.1 to 10 Hz
Single 1.8 V to 5.5 V Supply Voltage Range
Rail-to-Rail Input and Output
Internal RF/EMI Filter
Extended Temperature Range: −40℃ to +125℃
Applications
Battery-Powered Instruments:
– Consumer, Industrial, Medical, Notebooks
Wearable Fitness Devices
Audio Outputs
Sensor Signal Conditioning:
– Sensor Interfaces, Loop-Powered, Active Filters
Wireless Sensors:
– Home Security, Remote Sensing, Wireless Metering
Pin Configurations (Top View)
LTC8821
LTC8822
LTC8822
LTC8824
SOT23-5L / SC70-5L
DFN-8L
SOIC-8L / MSOP-8L
SOIC-14L / TSSOP-14L
OUT
1
–VS
2
+IN
3
5
4
+VS
–IN
LTC8823
OUTA 1
8
+VS
–INA 2
7
OUTB
+INA 3
6
–INB
–VS 4
5
+INB
OUTA
–INA
1
2
8
7
A
1
–VS
2
–IN
3
5
4
OUTB
OUTA
1
14
OUTD
–INA
2
13
–IND
A
+INA
3
–VS
4
B
SOT23-5L / SC70-5L
+IN
+VS
+VS
OUT
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
D
6
–INB
+INA
3
12
+IND
5
+INB
+VS
4
11
–VS
+INB
5
10
+INC
–INB
6
9
–INC
OUTB
7
8
OUTC
B
C
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
P-2
LTC8821, LTC8822, LTC8824
Pin Description
Symbol
Description
–IN
Inverting input of the amplifier.
+IN
Non-inverting input of the amplifier.
+VS
Positive (highest) power supply.
–VS
Negative (lowest) power supply.
OUT
Amplifier output.
Ordering Information
Type Number
Package Name
Package Quantity
Marking Code
LTC8821XT5/R6
SOT23-5
Tape and Reel, 3 000
AL1
LTC8821XC5/R6
SC70-5
Tape and Reel, 3 000
AL1
LTC8822XF8/R6
DFN2x2-8L
Tape and Reel, 3 000
AL2
LTC8822XF8S/R10
DFN1.5x1.5-8L
Tape and Reel, 5 000
AL2
LTC8822XS8/R8
SO-8
Tape and Reel, 4 000
AL2 X
LTC8822XV8/R6
MSOP-8
Tape and Reel, 3 000
AL2X
LTC8823XT5/R6
SOT23-5
Tape and Reel, 3 000
AL3
LTC8823XC5/R6
SC70-5
Tape and Reel, 3 000
AL3
LTC8824XS14/R5
SO-14
Tape and Reel, 2 500
AL4 X
LTC8824XT14/R6
TSSOP-14
Tape and Reel, 3 000
AL4 X
Limiting Value
In accordance with the Absolute Maximum Rating System (IEC 60134).
Parameter
Absolute Maximum Rating
Supply Voltage, VS+ to VS–
10.0 V
Signal Input Terminals: Voltage, Current
VS– – 0.3 V to VS+ + 0.3 V, ±10 mA
Output Short-Circuit
Continuous
Storage Temperature Range, Tstg
–65 ℃ to +150 ℃
Junction Temperature, TJ
150 ℃
Lead Temperature Range (Soldering 10 sec)
260 ℃
ESD Rating
Parameter
Electrostatic
Discharge
Voltage
Item
Value
Human body model (HBM), per MIL-STD-883J / Method 3015.9 (1)
±5 000
Charged device model (CDM), per ESDA/JEDEC JS-002-2014
±2 000
Machine model (MM), per JESD22-A115C
(2)
Unit
±250
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
V
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-3
Electrical Characteristics
VS = 5.0V, TA = +25℃, VCM = VS /2, VO = VS /2, and RL = 10kΩ connected to VS /2, unless otherwise noted.
Boldface limits apply over the specified temperature range, TA = −40 to +125 ℃.
Symbol
Parameter
Conditions
Min.
Typ.
Max.
±0.5
±2.5
Unit
OFFSET VOLTAGE
VOS
Input offset voltage
VOS TC
Offset voltage drift
TA = −40 to +125 ℃
PSRR
Power supply
rejection ratio
VS = 2.0 to 5.5 V, VCM < VS+ − 2V
98
TA = −40 to +125 ℃
88
TA = −40 to +125 ℃
±2.8
±0.5
±3
115
mV
μV/℃
dB
INPUT BIAS CURRENT
1
IB
IOS
Input bias current
TA = +85 ℃
150
TA = +125 ℃
500
Input offset current
pA
1
pA
μVP-P
NOISE
Vn
Input voltage noise
f = 0.1 to 10 Hz
6
en
Input voltage noise
density
f = 10 kHz
62
f = 1 kHz
63
In
Input current noise
density
f = 1 kHz
5
nV/√Hz
fA/√Hz
INPUT VOLTAGE
VCM
CMRR
Common-mode
voltage range
Common-mode
rejection ratio
VS––0.1
VS++0.1
TA = −40 to +125 ℃
VS–
VS+–0.1
VS = 5.5 V, VCM = −0.1 to 5.5 V
76
VCM = 0 to 5.3 V, TA = −40 to +125 ℃
70
VS = 2.0 V, VCM = −0.1 to 2.0 V
72
VCM = 0 to 1.8 V, TA = −40 to +125 ℃
68
V
92
86
dB
INPUT IMPEDANCE
RIN
CIN
Input resistance
Input capacitance
100
GΩ
Differential
2.0
Common mode
3.5
pF
OPEN-LOOP GAIN
AVOL
Open-loop voltage
gain
RL = 25 kΩ, VO = 0.05 to 3.5 V
86
TA = −40 to +125 ℃
80
RL = 5 kΩ, VO = 0.15 to 3.5 V
80
TA = −40 to +125 ℃
74
97
92
dB
FREQUENCY RESPONSE
Gain bandwidth
product
Slew rate
THD+N
Total harmonic
distortion + noise
tS
Settling time
GBW
SR
500
kHz
G = +1, CL = 100 pF, VO = 1.5 to 3.5 V
0.25
V/μs
G = +1, f = 1 kHz, RL = 2 kΩ,
VO = 1 VRMS
0.005
%
To 0.1%, G = +1, 1V step
6
To 0.01%, G = +1, 1V step
7
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
μs
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-4
Electrical Characteristics (continued)
VS = 5.0V, TA = +25℃, VCM = VS /2, VO = VS /2, and RL = 10kΩ connected to VS /2, unless otherwise noted.
Boldface limits apply over the specified temperature range, TA = −40 to +125 ℃.
Symbol
tOR
Parameter
Overload recovery
time
Conditions
Min.
To 0.1%, VIN * Gain > VS
Typ.
Max.
10
Unit
μs
OUTPUT
VOH
High output voltage
swing
RL = 25 kΩ
VS+–8
VS+–5
RL = 5 kΩ
VS+–36
VS+–26
VOL
Low output voltage
swing
RL = 25 kΩ
VS–+4
VS–+6
RL = 5 kΩ
VS–+16
VS–+24
ISC
Short-circuit current
mV
±45
mV
mA
POWER SUPPLY
VS
Operating supply
voltage
IQ
Quiescent current
(per amplifier)
1.8
5.5
VS = 2.0V, TA = +25℃
5.2
6.5
VS = 5.5V, TA = +25℃
6.6
8.5
TA = −40 to +125 ℃
V
μA
12
THERMAL CHARACTERISTICS
TA
θJA
Operating
temperature range
Package Thermal
Resistance
-40
+125
SC70-5L
333
SOT23-5L
190
DFN2x2-8L
80
MSOP-8L
216
SOIC-8L
125
TSSOP-14L
112
SOIC-14L
115
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
℃
℃/W
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-5
Typical Performance Characteristics
At TA = +25℃, VCM = VS /2, and RL = 10kΩ connected to VS /2, unless otherwise noted.
CL=10pF
80
120
50
100
45
AOL (dB)
60
60
40
40
20
20
0
0
Phase (deg)
80
-20
-20
-40
-40
1000
Closed Loop Gain (dB)
100
-60
10k
100k
CL=50pF
40
35
30
25
20
15
10
1M
10
100
Frequency (Hz)
100k
Closed-Loop Gain as a function of Frequency.
10
Quiescent Current (μA)
10
Quiescent Current (μA)
10k
Frequency (Hz)
Open-loop Gain and Phase as a function of
Frequency.
8
6
4
2
8
6
4
2
0
0
1.5
2
2.5
3
3.5
4
4.5
5
-50
5.5
Quiescent Current as a function of Supply Voltage.
900
800
0
25
50
75
100
125
Quiescent Current as a function of Temperature.
140
VCM = –VS
5,000 Samples
120
Noise (nV/rtHz)
1000
-25
Temperature (℃)
Supply Voltage (V)
Distribution (Units)
1k
700
600
500
400
300
100
80
60
40
200
100
20
0
0
10
Offset Voltage (mV)
Offset Voltage Production Distribution
100
1k
10k
100k
Frequency (Hz)
Input Voltage Noise Spectral Density as a function of
Frequency.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-6
Typical Performance Characteristics (continued)
140
140
120
120
100
100
PSRR (dB)
CMRR (dB)
At TA = +25℃, VCM = VS /2, and RL = 10kΩ connected to VS /2, unless otherwise noted.
80
60
80
60
40
40
20
20
0
0
1
10
100
1k
10k
100k
1M
1
Frequency (Hz)
10
100
1k
10k
100k
Frequency (Hz)
Common-mode Rejection Ratio as a function of
Frequency.
Power Supply Rejection Ratio as a function of
Frequency.
50mV/div
CL=20pF
1 V/div
1M
CL = 20pF
AV = +1
50 μs/div
5μs/div
Large Signal Step Response (4V Step).
Small Signal Step Response (200mV Step).
CL=100pF
20mV/div
20mV/div
CL=20pF
5μs/div
5μs/div
Small Signal Step Response (100mV Step).
Small Signal Step Response (100mV Step).
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-7
Typical Performance Characteristics (continued)
At TA = +25℃, VCM = VS /2, and RL = 10kΩ connected to VS /2, unless otherwise noted.
80
Sourcing
Current
Output Voltage (V)
4
3
–40℃
+125℃
+25℃
2
1
Sinking Current
0
Short-circuit Current (mA)
5
60
–ISC
40
+ISC
20
0
0
10
20
30
40
50
60
2
3
3.5
4
4.5
5
5.5
Supply Voltage (V)
Output Current (mA)
Output Voltage Swing as a function of Output
Current.
2.5
Short-circuit Current as a function of Supply
Voltage.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
P-8
LTC8821, LTC8822, LTC8824
Application Notes
Featuring a maximized ratio of GBW-to-supply
current, low operating supply voltage, low input bias
current, and rail-to-rail inputs and outputs, the
LTC882x family is an excellent choice for precision
or general-purpose, low-current, low-voltage,
battery-powered
applications.
These
CMOS
operational amplifiers consume an ultra-low 6.6-μA
(typically at 5.5-V supply voltage) supply current per
amplifier. The LTC882x family is unity-gain stable
with a 500-kHz GBW product, driving capacitive loads
up to 20-pF. The capacitive load can be increased to
500-pF when the amplifier is configured for a 5-V/V
gain.
OPERATING VOLTAGE
The LTC882x family is optimized for operation at
voltages as low as +1.8 V (±0.9 V) and up to +5.5 V
(±2.75 V). In addition, many specifications apply from
–40 ℃ to +125 ℃. Parameters that vary significantly
with operating voltages or temperature are
illustrated in the Typical Characteristics graphs.
INPUT EMI FILTER AND CLAMP CIRCUIT
Figure 1 shows the input EMI filter and clamp circuit.
The LTC882x op-amps have internal ESD protection
diodes (D1, D2, D3, and D4) that are connected
between the inputs and each supply rail. These
diodes protect the input transistors in the event of
electrostatic discharge and are reverse biased
during normal operation. This protection scheme
allows voltages as high as approximately 300-mV
beyond the rails to be applied at the input of either
terminal without causing permanent damage. These
ESD protection current-steering diodes also provide
in-circuit, input overdrive protection, as long as the
current is limited to 10-mA as stated in the Absolute
Maximum Ratings.
VS+
D1
IN+
D2
RAIL-TO-RAIL INPUT
The input common-mode voltage range of the
LTC882x series extends 100-mV beyond the negative
and positive supply rails. This performance is
achieved with a complementary input stage: an Nchannel input differential pair in parallel with a Pchannel differential pair. The N-channel pair is active
for input voltages close to the positive rail, typically
VS+–1.4 V to the positive supply, whereas the Pchannel pair is active for inputs from 100-mV below
the negative supply to approximately VS+–1.4 V. There
is a small transition region, typically VS+–1.2 V to VS+–1
V, in which both pairs are on. This 200-mV transition
region can vary up to 200-mV with process variation.
Thus, the transition region (both stages on) can range
from VS+–1.4 V to VS+–1.2 V on the low end, up to VS+–1
V to VS+–0.8 V on the high end. Within this transition
region, PSRR, CMRR, offset voltage, offset drift, and
THD can be degraded compared to device operation
outside this region.
The typical input bias current of the LTC882x opamps during normal operation is approximately 1-pA.
In overdriven conditions, the bias current can
increase significantly. The most common cause of an
overdriven condition occurs when the operational
amplifier is outside of the linear range of operation.
When the output of the operational amplifier is driven
to one of the supply rails, the feedback loop
requirements cannot be satisfied and a differential
input voltage develops across the input pins. This
differential input voltage results in activation of
parasitic diodes inside the front-end input chopping
switches that combine with electromagnetic
interference (EMI) filter resistors to create the
equivalent circuit. Notice that the input bias current
remains within specification in the linear region.
RS1
5kΩ
D3
CCM1
RS2 CDM
5kΩ
IN–
D4
CCM2
VS–
Figure 1. Input EMI Filter and Clamp Circuit
Operational amplifiers vary in susceptibility to EMI. If
conducted EMI enters the operational amplifier, the
dc offset at the amplifier output can shift from its
nominal value when EMI is present. This shift is a
result of signal rectification associated with the
internal semiconductor junctions. Although all
operational amplifier pin functions can be affected by
EMI, the input pins are likely to be the most
susceptible. The EMI filter of the LTC882x family is
composed of two 5-kΩ input series resistors (RS1 and
RS2), two common-mode capacitors (CCM1 and CCM2),
and a differential capacitor (CDM). These RC networks
set the −3 dB low-pass cutoff frequencies at 35-MHz
for common-mode signals, and at 22-MHz for
differential signals.
RAIL-TO-RAIL OUTPUT
Designed as a micro-power, low-noise operational
amplifier, the LTC882x delivers a robust output drive
capability. A class AB output stage with commonsource transistors is used to achieve full rail-to-rail
output swing capability. For resistive loads up to 25kΩ, the output swings typically to within 5 mV of
either supply rail regardless of the power-supply
voltage applied. Different load conditions change the
ability of the amplifier to swing close to the rails. For
resistive loads up to 5-kΩ, the output swings typically
to within 26-mV of the positive supply rail and within
16-mV of the negative supply rail.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-9
Application Notes (continued)
CAPACITIVE LOAD AND STABILITY
The LTC882x family of operational amplifiers is
unity-gain stable for loads up to 20-pF. However, the
capacitive load can be increased to 500-pF when the
amplifier is configured for a minimum gain of 5-V/V.
As with most amplifiers, driving larger capacitive
loads than specified may cause excessive overshoot
and ringing, or even oscillation. A heavy capacitive
load reduces the phase margin and causes the
amplifier frequency response to peak. Peaking
corresponds to overshooting or ringing in the time
domain. Therefore, it is recommended that external
compensation be used if the LTC882x family requires
greater
capacitive-drive
capability.
This
compensation is particularly important in the unitygain configuration, which is the worst case for
stability.
A quick and easy way to stabilize the op-amp for
capacitive load drive is by adding a series resistor,
RISO, between the amplifier output terminal and the
load capacitance, as shown in Figure 2. RISO isolates
the amplifier output and feedback network from the
capacitive load. The bigger the RISO resistor value, the
more stable VOUT will be. Note that this method
results in a loss of gain accuracy because RISO forms
a voltage divider with the RL. In unity gain
applications with relatively small RL (approximately
5-kΩ), the capacitive load can be increased up to 100pF.
RISO
VOUT
LTC882x
VIN
RL
CL
Figure 2. Indirectly Driving Heavy Capacitive Load
An improvement circuit is shown in Figure 3. It
provides DC accuracy as well as AC stability. The RF
provides the DC accuracy by connecting the inverting
signal with the output.
CF
RF
RISO
VOUT
LTC882x
VIN
CL
RL
The CF and RISO serve to counteract the loss of phase
margin by feeding the high frequency component of
the output signal back to the amplifier’s inverting
input, thereby preserving phase margin in the overall
feedback loop.
For no-buffer configuration, there are two others
ways to increase the phase margin: (a) by increasing
the amplifier’s gain, or (b) by placing a capacitor in
parallel with the feedback resistor to counteract the
parasitic capacitance associated with inverting node.
OVERLOAD RECOVERY
Overload recovery is defined as the time required for
the operational amplifier output to recover from a
saturated state to a linear state. The output devices
of the operational amplifier enter a saturation region
when the output voltage exceeds the rated operating
voltage, either because of the high input voltage or
the high gain. After the device enters the saturation
region, the charge carriers in the output devices
require time to return back to the linear state. After
the charge carriers return back to the linear state,
the device begins to slew at the specified slew rate.
Thus, the propagation delay in case of an overload
condition is the sum of the overload recovery time
and the slew time. The overload recovery time for
the LTC882x family is approximately 10-μs.
EMI REJECTION RATIO
Circuit performance is often adversely affected by
high frequency EMI. When the signal strength is low
and transmission lines are long, an op-amp must
accurately amplify the input signals. However, all opamp pins — the non-inverting input, inverting input,
positive supply, negative supply, and output pins —
are susceptible to EMI signals. These high frequency
signals are coupled into an op-amp by various
means, such as conduction, near field radiation, or
far field radiation. For example, wires and printed
circuit board (PCB) traces can act as antennas and
pick up high frequency EMI signals.
Amplifiers do not amplify EMI or RF signals due to
their relatively low bandwidth. However, due to the
nonlinearities of the input devices, op-amps can
rectify these out of band signals. When these high
frequency signals are rectified, they appear as a dc
offset at the output.
The LTC882x op-amps have integrated EMI filters at
their input stage. A mathematical method of
measuring EMIRR is defined as follows:
EMIRR = 20 log (VIN_PEAK / ΔVOS)
INPUT-TO-OUTPUT COUPLING
Figure 3. Indirectly Driving Heavy Capacitive Load
with DC Accuracy
To minimize capacitive coupling, the input and output
signal traces should not be parallel. This helps
reduce unwanted positive feedback.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-10
Application Notes (continued)
MAXIMIZING PERFORMANCE THROUGH PROPER
LAYOUT
To achieve the maximum performance of the
extremely high input impedance and low offset
voltage of the LTC882x op-amps, care is needed in
laying out the circuit board. The PCB surface must
remain clean and free of moisture to avoid leakage
currents between adjacent traces. Surface coating of
the circuit board reduces surface moisture and
provides a humidity barrier, reducing parasitic
resistance on the board. The use of guard rings
around the amplifier inputs further reduces leakage
currents. Figure 4 shows proper guard ring
configuration and the top view of a surface-mount
layout. The guard ring does not need to be a specific
width, but it should form a continuous loop around
both inputs. By setting the guard ring voltage equal to
the voltage at the non-inverting input, parasitic
capacitance is minimized as well. For further
reduction of leakage currents, components can be
mounted to the PCB using Teflon standoff insulators.
Guard
Ring
+IN
–IN
+VS
Figure 4. Use a guard ring around sensitive pins
Other potential sources of offset error are
thermoelectric voltages on the circuit board. This
voltage, also called Seebeck voltage, occurs at the
junction of two dissimilar metals and is proportional
to the temperature of the junction. The most common
metallic junctions on a circuit board are solder-toboard trace and solder-to-component lead. If the
temperature of the PCB at one end of the component
is different from the temperature at the other end,
the resulting Seebeck voltages are not equal,
resulting in a thermal voltage error.
This thermocouple error can be reduced by using
dummy components to match the thermoelectric
error source. Placing the dummy component as
close as possible to its partner ensures both
Seebeck voltages are equal, thus canceling the
thermocouple error. Maintaining a constant ambient
temperature on the circuit board further reduces this
error. The use of a ground plane helps distribute heat
throughout the board and reduces EMI noise pickup.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-11
Typical Application Circuits
DIFFERENTIAL AMPLIFIER
monitoring applications, 50-mV is adequate.
3. Calculate R1 as follows:
R1 = RF×(VHYST÷VBATT) ≈ 10MΩ×(50mV÷2.4V) =
210kΩ
R2
R1
Vn
LTC882x
4. Select a threshold voltage for VIN rising (VTS) =
2.0V.
VOUT
Vp
5. Calculate R2 as follows:
R2 = 1÷[VTS÷(VREF×R1)－1÷R1－1÷RF] =
1÷[2V÷(1.2V×210kΩ)－1÷210kΩ－1÷10MΩ]
= 325kΩ
R3
R4
VREF
Figure 5. Differential Amplifier
The circuit shown in Figure 5 performs the difference
function. If the resistors ratios are equal R4/R3 = R2/R1,
then:
6. Calculate RBIAS: The minimum supply voltage for
this circuit is 1.8V. Providing 5μA of supply
current assures proper operation. Therefore:
RBIAS = (VBATTMIN－VREF)÷IBIAS = (1.8V－1.2V)÷ 5μA
= 120kΩ
VOUT = (Vp – Vn) × R2/R1 + VREF
INSTRUMENTATION AMPLIFIER
RF
R1
RG
IN+
+
VREF
R1
R2
R2
R1
IBIAS
VBATT
RBIAS
LTC882x
LTC882x
VSTATUS
LTC882x
IN–
R2
VOUT
V1
VREF
V2
VOUT =(V1 V2 )(1
R1 2 R1
) VREF
R2 RG
Figure 7. Battery Monitor
Figure 6. Instrumentation Amplifier
The LTC882x family is well suited for conditioning
sensor signals in battery-powered applications.
Figure 6 shows a two op-amp instrumentation
amplifier, using the LTC882x op-amps. The circuit
works well for applications requiring rejection of
common-mode noise at higher gains. The reference
voltage (VREF) is supplied by a low-impedance
source. In single voltage supply applications, the VREF
is typically VS/2.
PORTABLE GAS METER
VS
½
LTC8822
C
S
REF
RF
W
RB
BATTERY MONITORING
The low operating voltage and quiescent current of
the LTC882x family make it an excellent choice for
battery monitoring applications, as shown in Figure 7.
In this circuit, VSTATUS is high as long as the battery
voltage remains above 2-V (VREF = 1.2V). A low-power
reference is used to set the trip point. Resistor
values are selected as follows:
C2
C1
RL
VS
½
LTC8822
R1
R1
Figure 8. Portable Gas Meter Application
1. RF Selecting: Select RF such that the current
through RF is approximately 1000x larger than the
maximum bias current over temperature:
RF = VREF÷(1000×IBMAX) = 1.2V÷(1000×100pA) =
12MΩ ≈ 10MΩ
2. Choose the hysteresis voltage, VHYST. For battery
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
VOUT
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
P-12
LTC8821, LTC8822, LTC8824
Tape and Reel Information
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
B0 W
Reel
Diameter
A0
Cavity
A0
B0
K0
W
P1
Reel
Width (W1)
Dimension designed to accommodate the component width
Dimension designed to accommodate the component length
Dimension designed to accommodate the component thickness
Overall width of the carrier tape
Pitch between successive cavity centers
QUADRANT ASSIGNMENTS FOR PIN 1 ORIETATION IN TAPE
Sprocket Holes
Q1
Q2
Q1
Q2
Q3
Q4
Q3
Q4
User Direction of Feed
Pocket Quadrants
* All dimensions are nominal
Device
LTC8821XT5/R6
Package
Pins
Type
SOT23
5
SPQ
3 000
Reel
Reel
Diameter Width W1
(mm)
(mm)
178
9.0
A0
(mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
(mm)
Pin 1
Quadrant
3.3
3.2
1.5
4.0
8.0
Q3
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
P-13
LTC8821, LTC8822, LTC8824
Package Outlines
DIMENSIONS, SC70-5L (SOT353)
A2
A
Symbol
A1
D
e1
A
A1
A2
b
C
D
E
E1
e
e1
L
L1
θ
θ
e
L
E1
E
L1
b
Dimensions
In Millimeters
Min
Max
0.90
1.10
0.00
0.10
0.90
1.00
0.15
0.35
0.08
0.15
2.00
2.20
1.15
1.35
2.15
2.45
0.65 typ.
1.20
1.40
0.525 ref.
0.26
0.46
0°
8°
C
RECOMMENDED SOLDERING FOOTPRINT, SC70-5L (SOT353)
0.50
0.0197
0.65
0.0256
0.65
0.0256
0.40
0.0157
1.9
0.0748
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
Dimensions
In Inches
Min
Max
0.035
0.043
0.000
0.004
0.035
0.039
0.006
0.014
0.003
0.006
0.079
0.087
0.045
0.053
0.085
0.096
0.026 typ.
0.047
0.055
0.021 ref.
0.010
0.018
0°
8°
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-14
Package Outlines (continued)
DIMENSIONS, SOT23-5L
A2
A
A1
D
e1
Symbol
A
A1
A2
b
c
D
E1
E
e
e1
L
L1
θ
θ
L
E
E1
L1
e
b
Dimensions
In Millimeters
Min
Max
1.25
0.04
0.10
1.00
1.20
0.33
0.41
0.15
0.19
2.820
3.02
1.50
1.70
2.60
3.00
0.95 BSC
1.90 BSC
0.60 REF
0.30
0.60
0°
8°
Dimensions
In Inches
Min
Max
0.049
0.002
0.004
0.039
0.047
0.013
0.016
0.006
0.007
0.111
0.119
0.059
0.067
0.102
0.118
0.037 BSC
0.075 BSC
0.024 REF
0.012
0.024
0°
8°
c
RECOMMENDED SOLDERING FOOTPRINT, SOT23-5L
1.0
0.039
0.95
0.037
0.95
0.037
0.7
0.028
2.4
0.094
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-15
Package Outlines (continued)
DIMENSIONS, DFN1.5x1.5-8L
SIDE VIEW
A
A1
TOP VIEW
b
Symbol
A
A1
b
D
D2
E
E2
e
L
D2
E
Min.
0.48
L
E2
PIN#1
0.15
1.45
1.15
1.45
0.65
0.125
Millimeters
Nom.
0.53
0.127 REF.
0.20
1.50
1.20
1.50
0.70
0.40 BSC.
0.175
D
e
PIN#1
BOTTOM VIEW
RECOMMENDED SOLDERING FOOTPRINT, DFN1.5x1.5-8L
1.30
0.0512
PACKAGE
OUTLINE
8X
0.80
0.0315
0.40
0.0157
1.80
0.0709
1
0.40
PITCH
0.0157
0.25
8X 0.0098
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
Max.
0.58
0.25
1.55
1.25
1.55
0.75
0.225
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-16
Package Outlines (continued)
DIMENSIONS, DFN2x2-8L
E
A
c
A1
1
Nd
D1
2
D
b1
Exposed Thermal
Pad Zone
L
h
E1
h
2
e
Symbol
Min.
0.70
A
A1
b
b1
c
D
D1
Nd
E
E1
e
L
h
0.20
0.18
1.90
1.10
1.90
0.60
0.30
0.15
Millimeters
Nom.
0.75
0.02
0.25
0.18 REF
0.20
2.00
1.20
1.50BSC
2.00
0.70
0.50BSC
0.35
0.20
1
b
BOTTOM VIEW
RECOMMENDED SOLDERING FOOTPRINT, DFN2x2-8L
1.60
0.0630
PACKAGE
OUTLINE
8X
0.50
0.0197
1.00
0.0394
2.30
0.0906
1
0.50
PITCH
0.0197
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
0.30
8X 0.0118
mm
( inches
)
Max.
0.80
0.05
0.30
0.25
2.10
1.30
2.10
0.80
0.40
0.25
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-17
Package Outlines (continued)
DIMENSIONS, MSOP-8L
A2
A
A1
D
b
Symbol
e
A
A1
A2
b
C
D
E
E1
e
L
θ
L
E1
E
Dimensions
In Millimeters
Min
Max
0.800
1.100
Dimensions
In Inches
Min
Max
0.031
0.043
0.050
0.150
0.750
0.950
0.290
0.380
0.150
0.200
2.900
3.100
2.900
3.100
4.700
5.100
0.650 TYP.
0.400
0.700
0°
8°
0.002
0.006
0.030
0.037
0.011
0.015
0.006
0.008
0.114
0.122
0.114
0.122
0.185
0.201
0.026 TYP.
0.016
0.028
0°
8°
θ
C
RECOMMENDED SOLDERING FOOTPRINT, MSOP-8L
8X
(0.45)
MAX
(0.018)
(1.45)
MAX
(0.057)
8X
4.40
(5.85)
MAX
0.173
(0.230)
(2.95)
MIN
(0.116)
0.65
PITCH
0.026
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-18
Package Outlines (continued)
DIMENSIONS, SOIC-8L
A2
A
A1
D
b
Symbol
e
A
A1
A2
b
C
D
E
E1
e
L
θ
L
E
E1
θ
Dimensions
In Millimeters
Min
Max
1.370
1.670
0.070
0.170
1.300
1.500
0.306
0.506
0.203 TYP.
4.700
5.100
3.820
4.020
5.800
6.200
1.270 TYP.
0.450
0.750
0°
8°
Dimensions
In Inches
Min
Max
0.054
0.066
0.003
0.007
0.051
0.059
0.012
0.020
0.008 TYP.
0.185
0.201
0.150
0.158
0.228
0.244
0.050 TYP.
0.018
0.030
0°
8°
C
RECOMMENDED SOLDERING FOOTPRINT, SOIC-8L
8X
5.40
0.213
(1.55)
MAX
(0.061)
(3.90)
MIN
(0.154)
1
(0.60)
MAX 8X
(0.024)
PITCH
1.270
0.050
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-19
Package Outlines (continued)
DIMENSIONS, TSSOP-14L
A3 A2
A
Symbol
A1
D
b
e
C
L1 L
E
E1
A
A1
A2
A3
b
C
D
E
E1
e
L1
L
θ
Dimensions
In Millimeters
Min
Max
1.200
0.050
0.150
0.900
1.050
0.390
0.490
0.200
0.290
0.130
0.180
4.860
5.060
6.200
6.600
4.300
4.500
0.650 TYP.
1.000 REF.
0.450
0.750
0°
8°
Dimensions
In Inches
Min
Max
0.047
0.002
0.006
0.035
0.041
0.015
0.019
0.008
0.011
0.005
0.007
0.191
0.199
0.244
0.260
0.169
0.177
0.026 TYP.
0.039 REF.
0.018
0.030
0°
8°
θ
RECOMMENDED SOLDERING FOOTPRINT, TSSOP-14L
14X
(1.45)
MAX
(0.057)
(4.40)
MIN
(0.173)
PITCH
0.65
0.026
1
5.90
0.232
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
14X
(0.45)
MAX
(0.018)
mm
( inches
)
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
LTC8821, LTC8822, LTC8824
P-20
Package Outlines (continued)
DIMENSIONS, SOIC-14L
A3
A2
A
A1
D
b
C
e
L1 L
E
Symbol
E1
A
A1
A2
A3
b
C
D
E
E1
e
L1
L
θ
Dimensions
In Millimeters
Min
Max
1.450
1.850
0.100
0.300
1.350
1.550
0.550
0.750
0.406 TYP.
0.203 TYP.
8.630
8.830
5.840
6.240
3.850
4.050
1.270 TYP.
1.040 REF.
0.350
0.750
2°
8°
Dimensions
In Inches
Min
Max
0.057
0.073
0.004
0.012
0.053
0.061
0.022
0.030
0.016 TYP.
0.008 TYP.
0.340
0.348
0.230
0.246
0.152
0.159
0.050 TYP.
0.041 REF.
0.014
0.030
2°
8°
θ
RECOMMENDED SOLDERING FOOTPRINT, SOIC-14L
14X
5.40
0.213
(1.50)
MAX
(0.059)
(3.90)
MIN
(0.154)
1
(0.60)
MAX 14X
(0.024)
PITCH
1.270
0.050
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
mm
( inches
)
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
P-21
LTC8821, LTC8822, LTC8824
IMPORTANT NOTICE
Linearin is a global fabless semiconductor company specializing in advanced high-performance highquality analog/mixed-signal IC products and sensor solutions. The company is devoted to the innovation
of high performance, analog-intensive sensor front-end products and modular sensor solutions, applied
in multi-market of medical & wearable devices, smart home, sensing of IoT, and intelligent industrial &
smart factory (industrie 4.0). Linearin’s product families include widely-used standard catalog products,
solution-based application specific standard products (ASSPs) and sensor modules that help customers
achieve faster time-to-market products. Go to http://www.linearin.com for a complete list of Linearin
product families.
For additional product information, or full datasheet, please contact with the Linearin’s Sales Department
or Representatives.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
Linearin and designs are registered trademarks of Linearin Technology Corporation.
© Copyright Linearin Technology Corporation. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
FN1617-35.1c — Data Sheet
Ultra-Low Power 500kHz, 1.8V, Low-Noise, RRIO CMOS Amplifiers
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