The EC5741 series amplifiers are single supply, low power CMOS dual operational amplifier, these amplifiers offer bandwidth of 9KHz, rail-to-rail inputs and outputs, and single-supply operation from 1.4V to 5.5V. Low quiescent supply current of 1μA and very low input bias current of 1pA make the devices an ideal choice for low offset, low power consumption and high impedance applications such as smoke detectors, photodiode amplifiers, and other sensors.
The EC5741 is available in SOP-8 and SOT23-5 packages. The extended temperature range of -40oC to +85oC over all supply voltages offers additional design flexibility.
● Single-Supply Operation from +1.4V ~ +5.5V
● Rail-to-Rail Input / Output
● Gain-Bandwidth Product: 9kHz
● Low Input Bias Current: 1pA
● Low Offset Voltage：1mV
● Quiescent Current: 400nA
● Available in Space-Saving Package：
SOT23-5 and SOP8 Packages
● Portable Equipment
● Mobile Communications
● Smoke Detector
● Sensor Interface
● Medical Instrumentation
● Battery-Powered Instruments
● Handheld Test Equipment
Figure 1. Pin Assignment Diagram (SOT23-5 and SOP8 Package)
EC5741NN XX X
1. Y：Year code(D=2013;E=2014;F=2015…)
2. W：Week Code( The big character of A~Z is for the week of 1~26, and small a~z is for the week of 27~52.
1. LLLLL：Last five Number of Lot No
2. YY：Year Code
3. WW：Week Code
4. T：Internal Tracking Code
EC5741 series op amps are unity-gain stable and suitable for a wide range of general-purpose applications. The small footprints of the EC5741 series packages save space on printed circuit boards and enable the design of smaller electronic products.
Power Supply Bypassing and Board Layout
EC5741 series operates from a single 1.4V to 5.5V supply or dual ±0.7V 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 0.1μFceramic capacitors.
Low Supply Current
The low supply current (1.4μA) of EC5741 series will help to maximize battery life. They are ideal for battery powered Systems
EC5741 series operate under wide input supply voltage (1.4V to 5.5V). In addition, all temperature specifications apply from -40℃ to +125℃. Most behavior remains unchanged throughout the full operating voltage range. These guarantees ensure operation throughout the single Li-Ion battery lifetime.
The input common-mode range of EC5741 series 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 swing provides maximum possible dynamic range at the output. This is particularly important when operating in low supply voltages. The output voltage of EC5741 series can typically swing to less than 10mV from supply rail in light resistive loads (>100kΩ), and 60mV of supply rail in moderate resistive loads (10kΩ).
Capacitive Load Tolerance
The EC5741 series can directly drive 250pF capacitive load in unity-gain without oscillation. Increasing the gain enhances the amplifier’s ability to drive greater capacitive loads. In unity-gain configurations, the capacitive load drive can be improved by inserting an isolation resistor RISO in series with the capacitive load, as shown in Figure 2.
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 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
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 EC5741.
Figure 4. Differential Amplifier
If the resistor ratios are equal (i.e. R1=R3 and R2=R4), then
The input impedance of the previous differential amplifier is set by the resistors R1, R2, R3, and R4. To maintain the high input impedance, one can use a voltage follower in front of each input as shown in the following two instrumentation amplifiers.
Three-Op-Amp Instrumentation Amplifier
The three EC5741 can be used to build a three-op-amp instrumentation amplifier as shown in Figure 5.
Figure 5. Three-Op-Amp Instrumentation Amplifier
The amplifier in Figure 5 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.
Two-Op-Amp Instrumentation Amplifier
EC5741 can also be used to make a high input impedance two-op-amp instrumentation amplifier as shown in
Figure 6. Two-Op-Amp Instrumentation Amplifier
Where R1=R3 and R2=R4. If all resistors are equal, then Vo=2(VIP-VIN)
Single-Supply Inverting Amplifier
The inverting amplifier is shown in Figure 7. The capacitor C1 is used to block the DC signal going into the AC
signal source VIN. The value of R1 and C1 set the cut-off frequency to ƒC=1/(2πR1C1). The DC gain is defined
Figure 7. Single Supply Inverting Amplifier
Low Pass Active Filter
The low pass active filter is shown in Figure 8. The DC gain is defined by –R2/R1. The filter has
a -20dB/decade roll-off after its corner frequency ƒC=1/(2πR3C1).
Figure 8. Low Pass Active Filter
Sallen-Key 2nd Order Active Low-Pass Filter
EC5741 can be used to form a 2nd order Sallen-Key active low-pass filter as shown in Figure 9. The transfer function from VIN to VOUT is given by
Where the DC gain is defined by ALP=1+R3/R4, and the corner frequency is given by
The pole quality factor is given by
Let R1=R2=R and C1=C2=C, the corner frequency and the pole quality factor can be simplified as below
Figure 9. Sanllen-Key 2nd Order Active Low-Pass Filter
Sallen-Key 2nd Order high-Pass Active Filter
The 2 nd order Sallen-key high-pass filter can be built by simply interchanging those frequency selective components R1, R2, C1,and C2 as shown in Figure 10.
Figure 10. Sanllen-Key 2nd Order Active High-Pass Filter
Absolute Maximum Ratings
Power Supply Voltage (VDD to VSS)
Analog Input Voltage (IN+ or IN-)
PDB Input Voltage
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering, 10sec)
Package Thermal Resistance (TA=+25°C)
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.
(VDD = +5V, VSS = 0V, VCM = VDD/2, VOUT = VDD/2, RL=100K tied to VDD/2, SHDNB = VDD, TA = -40°C to
+85°C, unless otherwise noted. Typical values are at TA =+25°C.) (Notes 1)
Guaranteed by the PSRR test
Quiescent Supply Current
VDD = 5V
Shutdown Mode (PDB = VSS)
Input Offset Voltage
Input Offset Voltage
Input Bias Current
Input Offset Current
VDD=5.5 Vss-0.1V ≦VCM ≦VDD+0.1V
VDD = +1.8V to +5.5V
Open-Loop Voltage Gain
Output Voltage Swing
|VIN+-VIN-| ≧10mV VDD-VOH
RL = 100kΩ to VDD/2 VOL-Vss
|VIN+-VIN| ≧10mV VDD-VOH
RL = 50k to VDD/2 VOL-Vss
Sinking or Sourcing
Gain Bandwidth Product
Av = +1V/V
Av = +1V/V
To 0.1%, VOUT = 2V step
Av = +1V/V
Input Voltage Noise
VDD=5V, f = 1kHz
VDD=1.4V , f = 1kHz
Note 1: All devices are 100% production tested at TA = 25℃; all specifications over the automotive
temperature range is guaranteed by design, not production tested.
Note 2: Parameter is guaranteed by design.
TA =+25℃,VDD = +5V, Vss = 0V, VCM = VDD/2 , VOUT = VDD/2, RL=100K tied to VDD/2, CL=60pF,unless otherwise noted.