1
TP2121/TP2121N/TP2122/TP2124
1.8V, 600nA
Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Features
Supply Current: 950nA Maximum /Amplifier
Stable 18kHz GBWP with 10mV/μs Slew Rate
Offset Voltage: 1.5mV Maximum
Ultra-low VOS TC: 0.5μV/°C
Ultra-low Input Bias Current: 1fA Typical
High 120dB Open-Loop Voltage Gain
Unity Gain Stable for 1,000nF Capacitive Load
Rail-to-Rail Input/Output Voltage Range
Outputs Source and Sink 20mA of Load Current
No Phase Reversal for Overdriven Inputs
Ultra-low Single-Supply Operation Down to +1.8V
Shutdown Current: 3nA Typical (TP2121N)
–40°C to 125°C Operation Range
Robust 8kV – HBM and 2kV – CDM ESD Rating
Green, Popular Type Package
Applications
Handsets and Mobile Accessories
Current Sensing
Wireless Remote Sensors, Active RFID Readers
Environment/Gas/Oxygen Sensors
Threshold Detectors/Discriminators
Low Power Filters
Battery or Solar Powered Devices
Sensor Network Powered by Energy Scavenging
Description
The TP212x are ultra-low power, precision CMOS
op-amps featuring a maximum supply current of
950nA per amplifier with an ultra-low typical input
bias current of 1fA. Analog trim and calibration
routine reduce input offset voltage to below 1.5mV,
and the precision temperature compensation
technique makes offset voltage temperature drift at
0.5μV/°C, which allowing use of the TP212x in
systems with high gain without creating excessively
large output offset errors.
The TP212x are unity gain stable with 1,000nF
capacitive load with a constant 18kHz GBWP,
10mV/μs slew rate, which make them appropriate
for low frequency applications, such as battery
current monitoring and sensor conditioning. The
TP212x can operate from a single-supply voltage of
+1.8V to +6.0V or a dual-supply voltage of ±0.9V to
±3.0V. Beyond the rails input and rail-to-rail output
characteristics allow the full power-supply voltage to
be used for signal range.
The combined features make the TP212x ideal
choices for battery-powered applications because
they minimize errors due to power supply voltage
variations over the lifetime of the battery and
maintain high CMRR even for a rail-to-rail input
op-amp. Mobile accessories, wireless remote
sensing, backup battery sensors, and single-Li+ or
2-cell NiCd/Alkaline battery powered systems can
benefit from the features of the TP212x op-amps.
For applications that require power-down, the
TP2121N has a low-power shutdown mode that
reduces supply current to 3nA, and forces the output
into a high-impedance state.
3PEAK and the 3PEAK logo are registered trademarks of
3PEAK INCORPORATED. All other trademarks are the property
of their respective owners.
1
32
(1)
OUT CC R
VIR
R
Ultra-low Supply Current Op-amps:
Supply Current 0.3 μA 0.6 μA 4 μA
GBWP 10 kHz 18 kHz 150 kHz
Single TP2111 TP2121 TP1511
With Shut-down
TP2111N TP2121N TP1511N
Dual TP2112 TP2122 TP1512
Quad TP2114 TP2124 TP1514
TP2121 in Low Side Battery Current Sensor
2
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Pin Configuration
(Top View)
Order Information
Model Name Order Number Package Transport Media, Quantity Marking
Information
TP2121
TP2121-TR 5-Pin SOT23 Tape and Reel, 3,000 B2TYW
(1)
TP2121-CR 5-Pin SC70 Tape and Reel, 3,000 B2CYW
(1)
TP2121-SR 8-Pin SOIC Tape and Reel, 4,000 2121S
TP2121U TP2121U-TR 5-Pin SOT23 Tape and Reel, 3,000 B2UYW
(1)
TP2121N
TP2121N-TR 6-Pin SOT23 Tape and Reel, 3,000 B2NYW
(1)
TP2121N-VR 8-Pin MSOP Tape and Reel, 3,000 2121N
TP2121N-SR 8-Pin SOIC Tape and Reel, 4,000 2121NS
TP2122 TP2122-SR 8-Pin SOIC Tape and Reel, 4,000 B22S
TP2122-VR 8-Pin MSOP Tape and Reel, 3,000 B22V
TP2124 TP2124-SR 14-Pin SOIC Tape and Reel, 2,500 B24S
TP2124-TR 14-Pin TSSOP Tape and Reel, 3,000 B24T
Note (1): ‘YW’ is date coding scheme. 'Y' stands for calendar year, and 'W' stands for single workweek coding scheme.
Absolute Maximum Ratings
Note 1
Supply Voltage: V+ – V–....................................6.0V
Input Voltage............................. V– – 0.3 to V+ + 0.3
Input Current: +IN, –IN, SHDN Note 2.............. ±10mA
SHDN Pin Voltage……………………………V– to V+
Output Current: OUT.................................... ±20mA
Output Short-Circuit Duration Note 3…......... Indefinite
Operating Temperature Range.......–40°C to 125°C
Maximum Junction Temperature................... 150°C
Storage Temperature Range.......... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) ......... 260°C
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum
Rating condition for extended periods may affect device reliability and lifetime.
Note 2: The inputs are protected by ESD protection diodes to each power supply. If the input extends more than 500mV beyond the power supply, the input
current should be limited to less than 10mA.
3
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Note 3: A heat sink may be required to keep the junction temperature below the absolute maximum. This depends on the power supply voltage and how many
amplifiers are shorted. Thermal resistance varies with the amount of PC board metal connected to the package. The specified values are for short traces
connected to the leads.
ESD, Electrostatic Discharge Protection
Symbol Parameter Condition Minimum Level Unit
HBM Human Body Model ESD MIL-STD-883H Method 3015.8 8 kV
CDM Charged Device Model ESD JEDEC-EIA/JESD22-C101E 2 kV
4
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
5V Electrical Characteristics
The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 27°C.
VSUPPLY = 5V, VCM = VOUT = VSUPPLY/2, RL = 100kΩ, CL =60pF, VSHDN is unconnected.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage VCM = VDD/2 and VCM = GND ●
-1.5 ±0.1 +1.5 mV
VOS TC Input Offset Voltage Drift 0.5 μV/°C
IB Input Bias Current
TA=27 oC 1 fA
TA=85 oC 700 fA
TA=125 oC 45 pA
IOS Input Offset Current 1 fA
Vn Input Voltage Noise f = 0.1Hz to 10Hz 6.5 μVP-P
en Input Voltage Noise Density f = 1kHz 170 nV/√Hz
RIN Input Resistance > 1 TΩ
CIN Input Capacitance Differential
Common Mode 2.9
5 pF
CMRR Common Mode Rejection Ratio VCM = 0.1V to 4.9V ●
80 130 dB
VCM Common-mode Input Voltage
Range ●
V––0.3 V++0.3
V
PSRR Power Supply Rejection Ratio ●
60 92 dB
AVOL Open-Loop Large Signal Gain VOUT = 2.5V, RLOAD = 100kΩ ●
80 120 dB
VOUT = 0.1V to 4.9V, RLOAD = 100kΩ ●
80 120 dB
VOL, VOH Output Swing from Supply Rail RLOAD = 100kΩ 5 mV
ROUT Closed-Loop Output Impedance G = 1, f = 1kHz, IOUT = 0 0.4 Ω
RO Open-Loop Output Impedance f = 1kHz, IOUT = 0 2.6 Ω
ISC Output Short-Circuit Current Sink or source current 20 mA
VDD Supply Voltage 1.8 6.0 V
IQ Quiescent Current per Amplifier ●
600 950 nA
PM Phase Margin RLOAD = 100kΩ, CLOAD = 60pF 61 °
GM Gain Margin RLOAD = 100kΩ, CLOAD = 60pF -10 dB
GBWP Gain-Bandwidth Product f = 1kHz 18 kHz
tS
Settling Time, 1.5V to 3.5V, Unity
Gain
Settling Time, 2.45V to 2.55V,
Unity Gain
0.1%
0.01%
0.1%
0.01%
0.25
0.253
0.035
0.038
ms
SR Slew Rate AV = 1, VOUT = 1.5V to 3.5V, CLOAD =
60pF, RLOAD = 100kΩ 10 mV/μs
FPBW Full Power Bandwidth Note 2 2VP-P 600 Hz
IQ(off) Supply Current in Shutdown Note 1 3 nA
ISHDN Shutdown Pin Current Note 1 VSHDN = 0.5V
VSHDN = 1.5V
-10
-10 pA
ILEAK Output Leakage Current in
Shutdown Note 1
VSHDN = 0V, VOUT = 0V
VSHDN = 0V, VOUT = 5V
-3.6
3.6 pA
VIL SHDN Input Low Voltage Note 1 Disable ●
0.5 V
VIH SHDN Input High Voltage Note 1 Enable ●
1.0 V
Note 1: Specifications apply to the TP2121N with shutdown.
Note 2: Full power bandwidth is calculated from the slew rate FPBW = SR/π • VP-P.
5
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Typical Performance Characteristics
Small-Signal Step Response, 100mV Step
2.40
2.45
2.50
2.55
2.60
3579
50mV/div
2ms/div
Gain = +1
V
IN
Step = 100mV
C
LOAD
= 60pF
Large-Signal Step Response, 2V Step
1
2
3
4
25811
1V/div
3ms/div
Gain = +1
C
LOAD
= 60pF
R
LOAD
= 100kΩ
Open-Loop Gain and Phase
-50
0
50
100
150
1E-3 1E-1 1E+1 1E+3 1E+5 1E+7
GAIN AND PHASE (dB)
FREQUENCY (Hz)
Gain = 1
RLOAD = 100kΩ
CLOAD = 60pF
Phase
Gain
Phase Margin vs. CLOAD (Stable for Any CLOAD)
0
20
40
60
80
1E+0 1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
Phase (dB)
Load Capacitance (pF)
Gain = +1
R
LOAD
= 100k
Ω
Input Voltage Noise Spectral Density
100
1k
10k
1E-1 1E+0 1E+1 1E+2 1E+3
Input Noise Voltage (nV/√Hz)
FREQUENCY (Hz)
Common-Mode Rejection Ratio
30
60
90
120
150
1E-3 1E-1 1E+1 1E+3 1E+5 1E+7
CMRR (dB)
Frequency (Hz)
6
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Typical Performance Characteristics
Over-Shoot Voltage, CLOAD = 40nF, Gain = +1, RFB=100kΩ
2.4
2.45
2.5
2.55
2.6
246810
50mV/div
2ms/div
Gain = +1
V
IN
Step = 100mV
C
LOAD
= 40nF
Over-Shoot % vs. CLOAD, Gain = +1, RFB = 1MΩ
0%
10%
20%
30%
40%
50%
60%
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7
Overshoot and Undershoot (%)
Load Capacitance (pF)
Gain = +1
V
IN
Step = 200mV
Overshoot
Undershoot
Over-Shoot Voltage, CLOAD=40nF, Gain= -1, RFB=100kΩ
2.4
2.45
2.5
2.55
2.6
6 8 10 12 14
50mV/div
2ms/div
Gain = -1
VIN Step = 100mV
CLOAD = 40nF
Over-Shoot % vs. CLOAD, Gain = -1, RFB = 1MΩ
0%
10%
20%
30%
40%
50%
60%
1E+0 1E+2 1E+4 1E+6
Overshoot and Undershoot (%)
Load Capacitance (pF)
Gain = -1
V
IN
Step = 200mV
Overshoot
Undershoot
Power-Supply Rejection Ratio
0
20
40
60
80
1E-3 1E-2 1E-1 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5
PSRRN/PSRRP (dB)
Frequency (Hz)
PSRRN
PSRRP
VIN = -0.2V to 5.7V, No Phase Reversal
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
0 102030405060
AMPLITUDE (V)
TIME (ms)
7
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Typical Performance Characteristics
Quiescent Supply Current vs. Temperature
500.0
550.0
600.0
650.0
700.0
750.0
-40-200 20406080100
CURRENT (nA)
TEMPERATURE (
O
C)
Open-Loop Gain vs. Temperature
100
110
120
130
-40-20 0 20406080100
OPEN LOOP GAIN (dB)
TEMPERATURE (
O
C)
Quiescent Supply Current vs. Supply Voltage
400.0
450.0
500.0
550.0
600.0
650.0
700.0
750.0
1.8 2.6 3.4 4.2 5
CURRENT (nA)
POWER SUPPLY VOLTAGE (V)
85
O
C
27
O
C
-40
O
C
Short-Circuit Current vs. Supply Voltage
0
5
10
15
20
25
30
1.82.83.84.8
POWER SUPPLY VOLTAGE (V)
SHORT-CIRCUIT CURRENT (mA)
Input Offset Voltage Distribution
0
100
200
300
400
-1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6
Smpeles
Offset Voltage (mV)
Production Package Units
V
DD
=5V,
V
CM
<V
DD
‐1V,
2000 Samples
Input Offset Voltage vs. Common Mode Input Voltage
-0.1
0
0.1
0.2
0.3
0.4
012345
Input Offset Voltage(mV)
Common Mode Input Voltage(V)
T
A
= +85
O
CT
A
= +27
O
CT
A
= - 40
O
C
8
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Typical Performance Characteristics
Closed-Loop Output Impedance vs. Frequency
1
10
100
1k
10k
100k
1 10 100 1k 10k
OUTPUT IMPEDANCE (Ω)
FREQUENCY (Hz)
0.1Hz to 10Hz Time Domain Output Voltage Noise
-5
-4
-3
-2
-1
0
1
2
3
4
5
-6 -4 -2 0 2 4 6
PEAK-TO-PEAK Voltage (μV)
TIME (Seconds)
Pin Functions
–IN: Inverting Input of the Amplifier. Voltage range of
this pin can go from V– – 0.3V to V+ + 0.3V.
+IN: Non-Inverting Input of Amplifier. This pin has the
same voltage range as –IN.
V+ or +VS: Positive Power Supply. Typically the voltage
is from 1.8V to 5.5V. Split supplies are possible as long
as the voltage between V+ and V– is between 1.8V and
5.5V. A bypass capacitor of 0.1μF as close to the part as
possible should be used between power supply pins or
between supply pins and ground.
N/C: No Connection.
V– or –VS: Negative Power Supply. It is normally
tied to ground. It can also be tied to a voltage other
than ground as long as the voltage between V+ and
V– is from 1.8V to 5.5V. If it is not connected to
ground, bypass it with a capacitor of 0.1μF as close
to the part as possible.
SHDN: Active Low Shutdown. Shutdown threshold
is 1.0V above negative supply rail. If unconnected,
the amplifier is automatically enabled.
OUT: Amplifier Output. The voltage range extends
to within milli-volts of each supply rail.
Operation
The TP212x family input signal range extends beyond
the negative and positive power supplies. The output
can even extend all the way to the negative supply. The
input stage is comprised of two CMOS differential
amplifiers, a PMOS stage and NMOS stage that are
active over different ranges of common mode input
voltage. The Class-AB control buffer and output bias
stage uses a proprietary compensation technique to
take full advantage of the process technology to drive
very high capacitive loads. This is evident from the
transient over shoot measurement plots in the Typical
Performance Characteristics.
9
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Applications Information
Low Supply Voltage and Low Power Consumption
The TP212x family of operational amplifiers can operate with power supply voltages from 1.8V to 6.0V. Each amplifier
draws only 600nA quiescent current. The low supply voltage capability and low supply current are ideal for portable
applications demanding HIGH CAPACITIVE LOAD DRIVING CAPABILITY and CONSTANT WIDE BANDWIDTH. The
TP212x family is optimized for wide bandwidth low power applications. They have an industry leading high GBWP to
power ratio and are unity gain stable for 1,000nF capacitive load. When the load capacitance increases, the increased
capacitance at the output pushed the non-dominant pole to lower frequency in the open loop frequency response,
lowering the phase and gain margin. Higher gain configurations tend to have better capacitive drive capability than
lower gain configurations due to lower closed loop bandwidth and hence higher phase margin.
Low Input Referred Noise
The TP212x family provides a low input referred noise density of 170nV/√Hz at 1kHz. The voltage noise will grow
slowly with the frequency in wideband range, and the input voltage noise is typically 6.5μVP-P at the frequency of 0.1Hz
to 10Hz.
Low Input Offset Voltage
The TP212x family has a low offset voltage of 1.5mV maximum which is essential for precision applications. The offset
voltage is trimmed with a proprietary trim algorithm to ensure low offset voltage for precision signal processing
requirement.
Low Input Bias Current
The TP212x family is a CMOS OPA family and features very low input bias current in pA range. The low input bias
current allows the amplifiers to be used in applications with high resistance sources. Care must be taken to minimize
PCB Surface Leakage. See below section on “PCB Surface Leakage” for more details.
PCB Surface Leakage
In applications where low input bias current is critical, Printed Circuit Board (PCB) surface leakage effects need to be
considered. Surface leakage is caused by humidity, dust or other contamination on the board. Under low humidity
conditions, a typical resistance between nearby traces is 1012Ω. A 5V difference would cause 5pA of current to flow,
which is greater than the TP212x OPA’s input bias current at +27°C (±1fA, typical). It is recommended to use
multi-layer PCB layout and route the OPA’s -IN and +IN signal under the PCB surface.
The effective way to reduce surface leakage is to use a guard ring around sensitive pins (or traces). The guard ring is
biased at the same voltage as the sensitive pin. An example of this type of layout is shown in Figure 1 for Inverting
Gain application.
1. For Non-Inverting Gain and Unity-Gain Buffer:
a) Connect the non-inverting pin (VIN+) to the input with a wire that does not touch the PCB surface.
b) Connect the guard ring to the inverting input pin (VIN–). This biases the guard ring to the Common Mode input voltage.
2. For Inverting Gain and Trans-impedance Gain Amplifiers (convert current to voltage, such as photo detectors):
a) Connect the guard ring to the non-inverting input pin (VIN+). This biases the guard ring to the same reference voltage as
the op-amp (e.g., VDD/2 or ground).
b) Connect the inverting pin (VIN–) to the input with a wire that does not touch the PCB surface.
Figure 1
Ground Sensing and Rail to Rail Output
The TP212x family has excellent output drive capability, delivering over 10mA of output drive current. The output stage
is a rail-to-rail topology that is capable of swinging to within 5mV of either rail. Since the inputs can go 300mV beyond
either rail, the op-amp can easily perform ‘true ground’ sensing.
10
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
The maximum output current is a function of total supply voltage. As the supply voltage to the amplifier increases, the
output current capability also increases. Attention must be paid to keep the junction temperature of the IC below 150°C
when the output is in continuous short-circuit. The output of the amplifier has reverse-biased ESD diodes connected to
each supply. The output should not be forced more than 0.5V beyond either supply, otherwise current will flow through
these diodes.
ESD
The TP212x family has reverse-biased ESD protection diodes on all inputs and output. Input and out pins can not be
biased more than 300mV beyond either supply rail.
Shut-down
The single channel OPA versions have SHDN pins that can shut down the amplifier to typical 3nA supply current. The
SHDN pin voltage needs to be within 0.5V of V– for the amplifier to shut down. During shutdown, the output will be in
high output resistance state, which is suitable for multiplexer applications. When left floating, the SHDN pin is internally
pulled up to the positive supply and the amplifier remains enabled.
Driving Large Capacitive Load
The TP212x family of OPA is designed to drive large capacitive loads. Refer to Typical Performance Characteristics
for “Phase Margin vs. Load Capacitance”. As always, larger load capacitance decreases overall phase margin in a
feedback system where internal frequency compensation is utilized. As the load capacitance increases, the feedback
loop’s phase margin decreases, and the closed-loop bandwidth is reduced. This produces gain peaking in the
frequency response, with overshoot and ringing in output step response. The unity-gain buffer (G = +1V/V) is the most
sensitive to large capacitive loads.
When driving large capacitive loads with the TP212x OPA family (e.g., > 200 pF when G = +1V/V), a small series
resistor at the output (RISO in Figure 2) improves the feedback loop’s phase margin and stability by making the output
load resistive at higher frequencies.
Figure 2
Power Supply Layout and Bypass
The TP212x OPA’s power supply pin (VDD for single-supply) should have a local bypass capacitor (i.e., 0.01μF to
0.1μF) within 2mm for good high frequency performance. It can also use a bulk capacitor (i.e., 1μF or larger) within
100mm to provide large, slow currents. This bulk capacitor can be shared with other analog parts.
Ground layout improves performance by decreasing the amount of stray capacitance and noise at the OPA’s inputs
and outputs. To decrease stray capacitance, minimize PC board lengths and resistor leads, and place external
components as close to the op amps’ pins as possible.
Proper Board Layout
To ensure optimum performance at the PCB level, care must be taken in the design of the board layout. To avoid
leakage currents, the surface of the board should be kept clean and free of moisture. Coating the surface creates a
barrier to moisture accumulation and helps reduce parasitic resistance on the board.
Keeping supply traces short and properly bypassing the power supplies minimizes power supply disturbances due to
output current variation, such as when driving an ac signal into a heavy load. Bypass capacitors should be connected
as closely as possible to the device supply pins. Stray capacitances are a concern at the outputs and the inputs of the
amplifier. It is recommended that signal traces be kept at least 5mm from supply lines to minimize coupling.
A variation in temperature across the PCB can cause a mismatch in the Seebeck voltages at solder joints and other
points where dissimilar metals are in contact, resulting in thermal voltage errors. To minimize these thermocouple
effects, orient resistors so heat sources warm both ends equally. Input signal paths should contain matching numbers
and types of components, where possible to match the number and type of thermocouple junctions. For example,
dummy components such as zero value resistors can be used to match real resistors in the opposite input path.
11
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Matching components should be located in close proximity and should be oriented in the same manner. Ensure leads
are of equal length so that thermal conduction is in equilibrium. Keep heat sources on the PCB as far away from
amplifier input circuitry as is practical.
The use of a ground plane is highly recommended. A ground plane reduces EMI noise and also helps to maintain a
constant temperature across the circuit board.
BATTERY CURRENT SENSING
The Common Mode Input voltage Range of TP212x OPA series, which goes 0.3V beyond both supply rails, supports
their use in high-side and low-side battery current sensing applications. The low quiescent current (600nA, typical)
helps prolong battery life, and the rail-to-rail output supports detection of low currents.
The battery current (IDD) through the 10Ω resistor causes its top terminal to be more negative than the bottom terminal.
This keeps the Common Mode Input voltage below VDD, which is within its allowed range. The output of the OPA will
also be blow VDD, within its Maximum Output Voltage Swing specification.
13
2
D
D OUT
DD
VV
IRR
R
Figure 3
Instrumentation Amplifier
The TP212x OPA series is well suited for conditioning sensor signals in battery-powered applications. Figure 4 shows
a two op-amp instrumentation amplifier, using the TP212x OPA.
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, VREF is typically VDD/2.
11
12 2
2
=( )(1 )
OUT REF
G
RR
VVV V
RR
Figure 4
Buffered Chemical Sensor (pH) Probe
The TP212x OPA has input bias current in the pA range. This is ideal in buffering high impedance chemical sensors
such as pH probe. As an example, the circuit in Figure 5 eliminates expansive low-leakage cables that that is
required to connect pH probe to metering ICs such as ADC, AFE and/or MCU. A TP212x OPA and a lithium battery
are housed in the probe assembly. A conventional low-cost coaxial cable can be used to carry OPA’s output signal to
subsequent ICs for pH reading.
12
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Figure 5: Buffer pH Probe
Portable Gas Sensor Amplifier
Gas sensors are used in many different industrial and medical applications. Gas sensors generate a current that is
proportional to the percentage of a particular gas concentration sensed in an air sample. This output current flows
through a load resistor and the resultant voltage drop is amplified. Depending on the sensed gas and sensitivity of the
sensor, the output current can be in the range of tens of microamperes to a few milli-amperes. Gas sensor datasheets
often specify a recommended load resistor value or a range of load resistors from which to choose.
There are two main applications for oxygen sensors – applications which sense oxygen when it is abundantly present
(that is, in air or near an oxygen tank) and those which detect traces of oxygen in parts-per-million concentration. In
medical applications, oxygen sensors are used when air quality or oxygen delivered to a patient needs to be monitored.
In fresh air, the concentration of oxygen is 20.9% and air samples containing less than 18% oxygen are considered
dangerous. In industrial applications, oxygen sensors are used to detect the absence of oxygen; for example,
vacuum-packaging of food products.
The circuit in Figure 6 illustrates a typical implementation used to amplify the output of an oxygen detector. With the
components shown in the figure, the circuit consumes less than 600nA of supply current ensuring that small
form-factor single- or button-cell batteries (exhibiting low mAh charge ratings) could last beyond the operating life of
the oxygen sensor. The precision specifications of these amplifiers, such as their low offset voltage, low VOS TC, low
input bias current, high CMRR, and high PSRR are other factors which make these amplifiers excellent choices for this
application.
2
O
I
2
1 in Air ( 21% O )
0.7
OUT
DD
VV
IuA
Figure 6
13
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Package Outline Dimensions
SOT23-5 / SOT23-6
Symbol
Dimensions
In Millimeters
Dimensions
In Inches
Min Max Min Max
A1 0.000 0.100 0.000 0.004
A2 1.050 1.150 0.041 0.045
b 0.300 0.400 0.012 0.016
D 2.820 3.020 0.111 0.119
E 1.500 1.700 0.059 0.067
E1 2.650 2.950 0.104 0.116
e 0.950TYP 0.037TYP
e1 1.800 2.000 0.071 0.079
L1 0.300 0.460 0.012 0.024
θ 0° 8° 0° 8°
14
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Package Outline Dimensions
SC-70-5 / SC-70-6 (SOT353 / SOT363)
Symbol
Dimensions
In Millimeters
Dimensions In
Inches
Min Max Min Max
A1 0.000 0.100 0.000 0.004
A2 0.900 1.000 0.035 0.039
b 0.150 0.350 0.006 0.014
C 0.080 0.150 0.003 0.006
D 2.000 2.200 0.079 0.087
E 1.150 1.350 0.045 0.053
E1 2.150 2.450 0.085 0.096
e 0.650TYP 0.026TYP
e1 1.200 1.400 0.047 0.055
L1 0.260 0.460 0.010 0.018
θ 0° 8° 0° 8°
15
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
D
E1
b
E
A1
A2
e
θ
L1
C
Package Outline Dimensions
SO-8 (SOIC-8)
Package Outline Dimensions
Symbol
Dimensions
In Millimeters
Dimensions In
Inches
Min Max Min Max
A1 0.100 0.250 0.004 0.010
A2 1.350 1.550 0.053 0.061
b 0.330 0.510 0.013 0.020
C 0.190 0.250 0.007 0.010
D 4.780 5.000 0.188 0.197
E 3.800 4.000 0.150 0.157
E1 5.800 6.300 0.228 0.248
e 1.270TYP 0.050TYP
L1 0.400 1.270 0.016 0.050
θ 0° 8° 0° 8°
16
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
MSOP-8
Symbol
Dimensions
In Millimeters
Dimensions In
Inches
Min Max Min Max
A 0.800 1.200 0.031 0.047
A1 0.000 0.200 0.000 0.008
A2 0.760 0.970 0.030 0.038
b 0.30 TYP 0.012 TYP
C 0.15 TYP 0.006 TYP
D 2.900 3.100 0.114 0.122
e 0.65 TYP 0.026
E 2.900 3.100 0.114 0.122
E1 4.700 5.100 0.185 0.201
L1 0.410 0.650 0.016 0.026
θ 0° 6° 0° 6°
E1
e
E
A1
D
L1 L2
L
R
R1
θ
b
17
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
www.3peakic.com REV1.2
Package Outline Dimensions
SO-14 (SOIC-14)
Symbol
Dimensions
In Millimeters
MIN TYP MAX
A 1.35 1.60 1.75
A1 0.10 0.15 0.25
A2 1.25 1.45 1.65
b 0.36 0.49
D 8.53 8.63 8.73
E 5.80 6.00 6.20
E1 3.80 3.90 4.00
e 1.27 BSC
L 0.45 0.60 0.80
L1 1.04 REF
L2 0.25 BSC
θ 0° 8°
18
TP2121
/
TP2121N
/
TP2122
/
TP2124
1.8V, 600nA Nanopower, Rail-to-Rail Input/Output
Op-amps
REV1.2 www.3peakic.com
Package Outline Dimensions
TSSOP-14
Symbol
Dimensions
In Millimeters
MIN TYP MAX
A - - 1.20
A1 0.05 - 0.15
A2 0.90 1.00 1.05
b 0.20 - 0.28
c 0.10 - 0.19
D 4.86 4.96 5.06
E 6.20 6.40 6.60
E1 4.30 4.40 4.50
e 0.65 BSC
L 0.45 0.60 0.75
L1 1.00 REF
L2 0.25 BSC
R 0.09 - -
θ 0° - 8°
E
e
E1
A1
A2
A
D
L1 L2
L
R
R1
θ
c
