GS321/358/324
1MHZ CMOS Rail-to-Rail IO Opamp with RF Filter
Features
•
Single-Supply Operation from +2.1V ~ +5.5V
•
Small Package:
•
Rail-to-Rail Input / Output
GS321 Available in SOT23-5 and SC70-5 Packages
•
Gain-Bandwidth Product: 1MHz (Typ.)
GS358 Available in SOP-8, MSOP-8, DIP-8 and DFN-8
•
Low Input Bias Current: 1pA (Typ.)
Packages
•
Low Offset Voltage: 3.5mV (Max.)
GS324 Available in SOP-14 and TSSOP-14 Packages
•
Quiescent Current: 40µA per Amplifier (Typ.)
•
Operating Temperature: -40°C ~ +125°C
•
Embedded RF Anti-EMI Filter
General Description
μ
The GS321 family have a high gain-bandwidth product of 1MHz, a slew rate of 0.6V/ s, and a quiescent current of 40
μ
A/amplifier at 5V. The GS321 family is designed to provide optimal performance in low voltage and low noise systems. They
provide rail-to-rail output swing into heavy loads. The input common mode voltage range includes ground, and the maximum
℃ to
input offset voltage is 3.5mV for GS321 family. They are specified over the extended industrial temperature range (-40
+125
℃). The operating range is from 2.1V to 5.5V. The GS321 single is available in Green SC70-5 and SOT-23-5 packages.
The GS358 Dual is available in Green SOP-8, MSOP-8, DIP-8 and DFN-8 packages. The GS324 Quad is available in Green
SOP-14 and TSSOP-14 packages.
Applications
•
ASIC Input or Output Amplifier
•
Audio Output
•
Sensor Interface
•
Piezoelectric Transducer Amplifier
•
Medical Communication
•
Medical Instrumentation
•
Smoke Detectors
•
Portable Systems
Pin Configuration
GS321Y
OUT 1
5 VDD
VSS 2
IN+ 3
4 IN-
SOT23-5/SC70-5
Figure 1. Pin Assignment Diagram
V1
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GS321/358/324
Absolute Maximum Ratings
Condition
Min
Max
-0.5V
+7.5V
Analog Input Voltage (IN+ or IN-)
Vss-0.5V
VDD+0.5V
PDB Input Voltage
Vss-0.5V
+7V
-40°C
+125°C
Power Supply Voltage (VDD to Vss)
Operating Temperature Range
Junction Temperature
+160°C
Storage Temperature Range
-55°C
Lead Temperature (soldering, 10sec)
Package Thermal Resistance (TA=+25
+150°C
+260°C
℃)
SOP-8, θJA
125°C/W
MSOP-8, θJA
216°C/W
SOT23-5, θJA
190°C/W
SC70-5, θJA
333°C/W
ESD Susceptibility
HBM
6KV
MM
300V
Note: Stress greater than those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at these or any other conditions outside those indicated in the operational
sections of this specification are not implied. Exposure to absolute maximum rating conditions for extended periods may affect
reliability.
Package/Ordering Information
MODEL
GS321
GS358
GS324
V1
CHANNEL
Single
Dual
Quad
PACKAGE
PACKAGE
MARKING
DESCRIPTION
OPTION
INFORMATION
GS321-CR
SC70-5
Tape and Reel,3000
321
GS321-TR
SOT23-5
Tape and Reel,3000
321
GS321Y-CR
SC70-5
Tape and Reel,3000
321Y
GS321Y-TR
SOT23-5
Tape and Reel,3000
321Y
GS358-SR
SOP-8
Tape and Reel,4000
GS358
GS358-MR
MSOP-8
Tape and Reel,3000
GS358
GS358-DR
DIP-8
20Tube(1000pcs)
GS358
GS358-FR
DFN-8
Tape and Reel,3000
GS358
GS324-TR
TSSOP-14
Tape and Reel,3000
GS324
GS324-SR
SOP-14
Tape and Reel,2500
GS324
ORDER NUMBER
2/16
GS321/358/324
Electrical Characteristics
(At VS = +5V, RL = 100kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.)
GS321/358/324
PARAMETER
SYMBOL
CONDITIONS
TYP
+25
℃
MIN/MAX OVER TEMPERATURE
+25
℃
-40
℃ to +85℃
UNITS
MIN/MAX
mV
MAX
INPUT CHARACTERISTICS
Input Offset Voltage
VOS
VCM = VS/2
0.4
3.5
5.6
Input Bias Current
IB
1
pA
TYP
Input Offset Current
IOS
1
pA
TYP
Common-Mode Voltage Range
VCM
-0.1 to +5.6
V
TYP
Common-Mode Rejection Ratio
CMRR
Open-Loop Voltage Gain
Input Offset Voltage Drift
VS = 5.5V
VS = 5.5V, VCM = -0.1V to 4V
70
62
62
VS = 5.5V, VCM = -0.1V to 5.6V
68
56
55
RL = 5kΩ, VO = +0.1V to +4.9V
80
70
70
RL = 10kΩ, VO = +0.1V to +4.9V
100
90
85
dB
MIN
dB
MIN
AOL
∆VOS/∆T
2.7
µV/
℃
TYP
OUTPUT CHARACTERISTICS
VOH
RL = 100kΩ
4.997
4.990
4.980
V
MIN
VOL
RL = 100kΩ
3
10
20
mV
MAX
VOH
RL = 10kΩ
4.992
4.970
4.960
V
MIN
VOL
RL = 10kΩ
8
30
40
mV
MAX
84
60
45
mA
MIN
75
60
45
2.1
2.5
V
MIN
5.5
5.5
V
MAX
82
60
58
dB
MIN
40
60
80
µA
MAX
1
MHz
TYP
Output Voltage Swing from Rail
ISOURCE
Output Current
RL = 10Ω to VS/2
ISINK
POWER SUPPLY
Operating Voltage Range
Power Supply Rejection Ratio
PSRR
Quiescent Current / Amplifier
IQ
VS = +2.5V to +5.5V, VCM = +0.5V
DYNAMIC PERFORMANCE (CL = 100pF)
Gain-Bandwidth Product
Slew Rate
Settling Time to 0.1%
GBP
SR
G = +1, 2V Output Step
0.6
V/µs
TYP
tS
G = +1, 2V Output Step
5
µs
TYP
VIN ·Gain = VS
2.6
µs
TYP
f = 1kHz
27
nV / Hz
TYP
f = 10kHz
20
nV /
TYP
Overload Recovery Time
NOISE PERFORMANCE
Voltage Noise Density
V1
en
Hz
3/16
GS321/358/324
Typical Performance characteristics
o
At TA=+25 C, VS=+5V, and RL=100KΩ connected to VS/2, unless otherwise noted.
Large-Signal Step Response
Small-Signal Step Response
G=+1
CL=100pF
RL=100KΩ
Output Voltage (20mV/div)
Output Voltage (500mV/div)
G=+1
CL=100pF
RL=100KΩ
Time (2µs/div)
Supply Current vs. Supply Voltage
Short-Circuit Current vs. Supply Voltage
Supply Current (uA)
Short-Circuit Current (mA)
Time (4µs/div)
Supply Voltage (V)
Supply Voltage (V)
Output Voltage vs. Output Current
Output Voltage vs. Output Current
Vs=5V
Sinking Current
Output Current (mA)
V1
Output Voltage (V)
Output Voltage (V)
Sourcing Current
Sourcing Current
Vs=3V
Sinking Current
Output Current (mA)
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GS321/358/324
Typical Performance characteristics
o
At TA=+25 C, VS=+5V, and RL=100KΩ connected to VS/2, unless otherwise noted.
Supply Current vs. Temperature
Vs=5V
G=-5
VIN=500mV
℃
Input Voltage Noise Spectral Density vs. Frequency
Open Loop Gain, Phase Shift vs. Frequency at +5V
Open Loop Gain (dB)
Phase Shift (Degrees)
Temperature ( )
Voltage Noise (nV/√Hz)
Time (2µs/div)
Frequency (kHz)
CMRR vs. Frequency
PSRR vs. Frequency
PSRR (dB)
CMRR (dB)
Frequency (kHz)
Frequency (kHz)
V1
Supply Current (µA)
Overload Recovery Time
Frequency (kHz)
5/16
GS321/358/324
Application Note
Size
GS321 family series op amps are unity-gain stable and suitable for a wide range of general-purpose applications. The small
footprints of the GS321 family packages save space on printed circuit boards and enable the design of smaller electronic
products.
Power Supply Bypassing and Board Layout
GS321 family series operates from a single 2.1V to 5.5V supply or dual ±1.05V to ±2.75V supplies. For best performance, a
0.1µF ceramic capacitor should be placed close to the VDD pin in single supply operation. For dual supply operation, both VDD
and VSS supplies should be bypassed to ground with separate 0.1µF ceramic capacitors.
Low Supply Current
The low supply current (typical 40uA per channel) of GS321 family will help to maximize battery life. They are ideal for battery
powered systems
Operating Voltage
GS321 family operates under wide input supply voltage (2.1V to 5.5V). In addition, all temperature specifications apply from
o
o
-40 C to +125 C. Most behavior remains unchanged throughout the full operating voltage range. These guarantees ensure
operation throughout the single Li-Ion battery lifetime
Rail-to-Rail Input
The input common-mode range of GS321 family extends 100mV beyond the supply rails (VSS-0.1V to VDD+0.1V). This is
achieved by using complementary input stage. For normal operation, inputs should be limited to this range.
Rail-to-Rail Output
Rail-to-Rail output swing provides maximum possible dynamic range at the output. This is particularly important when
operating in low supply voltages. The output voltage of GS321 family can typically swing to less than 5mV from supply rail in
light resistive loads (>100kΩ), and 30mV of supply rail in moderate resistive loads (10kΩ).
Capacitive Load Tolerance
The GS321 family is optimized for bandwidth and speed, not for driving capacitive loads. Output capacitance will create a
pole in the amplifier’s feedback path, leading to excessive peaking and potential oscillation. If dealing with load capacitance is
a requirement of the application, the two strategies to consider are (1) using a small resistor in series with the amplifier’s output
and the load capacitance and (2) reducing the bandwidth of the amplifier’s feedback loop by increasing the overall noise gain.
Figure 2. shows a unity gain follower using the series resistor strategy. The resistor isolates the output from the capacitance
and, more importantly, creates a zero in the feedback path that compensates for the pole created by the output capacitance.
Figure 2. Indirectly Driving a Capacitive Load Using Isolation Resistor
The bigger the RISO resistor value, the more stable VOUT will be. However, if there is a resistive load RL in parallel with the
capacitive load, a voltage divider (proportional to RISO/RL) is formed, this will result in a gain error.
The circuit in Figure 3 is an improvement to the one in Figure 2. RF provides the DC accuracy by feed-forward the VIN to RL. CF
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GS321/358/324
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 the phase margin in the overall feedback loop. Capacitive drive can be increased
by increasing the value of CF. This in turn will slow down the pulse response.
Figure 3. Indirectly Driving a Capacitive Load with DC Accuracy
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GS321/358/324
Typical Application Circuits
Differential amplifier
The differential amplifier allows the subtraction of two input voltages or cancellation of a signal common the two inputs. It is useful
as a computational amplifier in making a differential to single-end conversion or in rejecting a common mode signal. Figure 4.
shown the differential amplifier using GS321 family.
Figure 4. Differential Amplifier
VOUT= ( RR13++RR24 ) RR14 VIN − RR12 VIP +( RR13++RR24 ) RR31 VREF
If the resistor ratios are equal (i.e. R1=R3 and R2=R4), then
VOUT =
R2
R1
(VIP − VIN ) + VREF
Low Pass Active Filter
The low pass active filter is shown in Figure 5. The DC gain is defined by –R2/R1. The filter has a -20dB/decade roll-off after its
corner frequency ƒC=1/(2πR3C1).
Figure 5. Low Pass Active Filter
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GS321/358/324
Instrumentation Amplifier
The triple GS321 family can be used to build a three-op-amp instrumentation amplifier as shown in Figure 6. The amplifier in
Figure 6 is a high input impedance differential amplifier with gain of R2/R1. The two differential voltage followers assure the high
input impedance of the amplifier.
Figure 6. Instrument Amplifier
.
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GS321/358/324
Package Information
MSOP-8
V1
10/16
GS321/358/324
SOP-8
V1
11/16
GS321/358/324
SOT23-5
V1
12/16
GS321/358/324
TSSOP-14
V1
13/16
GS321/358/324
SC70-5
V1
14/16
GS321/358/324
SOP-14
V1
15/16
GS321/358/324
DFN-8
V1
16/16