Datasheet ADA4522-1, ADA4522-2, ADA4522-4 (Analog Devices) - 28
| Manufacturer | Analog Devices |
| Description | 55 V, EMI Enhanced, Zero Drift, Ultralow Noise, Rail-to-Rail Output Operational Amplifiers |
| Pages / Page | 33 / 28 — ADA4522-1/ADA4522-2/ADA4522-4. Data Sheet. +5V. ADA4522-2. 100pF. VDD. … |
| Revision | F |
| File Format / Size | PDF / 1.1 Mb |
| Document Language | English |
ADA4522-1/ADA4522-2/ADA4522-4. Data Sheet. +5V. ADA4522-2. 100pF. VDD. 1/2. REF(+). DIN. 1µF. REF(–). DOUT/. RDY. R1 11.3kΩ. AD7791. 1kΩ. AIN(+). SCLK
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ADA4522-1/ADA4522-2/ADA4522-4 Data Sheet +5V V+ ADA4522-2 100pF VDD 1/2 REF(+) DIN 1µF REF(–) DOUT/ 100pF RDY R1 11.3kΩ R3 C3 AD7791 1kΩ 1µF AIN(+) SCLK C1 3.3µF RG C5 V CS EXC 60.4Ω R4 10µF 1kΩ LOAD SENSE+ AIN(–) CELL C2 3.3µF C4 GND 1µF OUT– OUT+ R2 11.3kΩ SENSE– 1/2
79 0
ADA4522-2
8- 16 13 Figure 83. Precision Weigh Scale Measurement System
PRECISION LOW-SIDE CURRENT SHUNT SENSOR I
Many applications require the sensing of signals near the
V R SY I S RL
positive or negative rails. Current shunt sensors are one such
0.1Ω
application and are mostly used for feedback control systems.
R2 R1
They are also used in a variety of other applications, including
100kΩ 100Ω VOUT*
power metering, battery fuel gauging, and feedback controls in
ADA4522-1/ VSY
industrial applications. In such applications, it is desirable to
ADA4522-2/ ADA4522-4
use a shunt with very low resistance to minimize series voltage drop. This configuration not only minimizes wasted power, but also allows the measurement of high currents while saving power.
R4 R3 100kΩ 100Ω
A typical shunt may be 100 mΩ. At a measured current of 1 A, the voltage produced from the shunt is 100 mV, and the ampli-
*V
0
OUT = AMPLIFIER GAIN × VOLTAGE ACROSS RS
08
= 1000 × R
fier error sources are not critical. However, at low measured current
S × I
68-
= 100 × I
31 1 in the 1 mA range, the 100 μV generated across the shunt demands Figure 84. Low-Side Current Sensing Circuit a very low offset voltage and drift amplifier to maintain absolute
PRINTED CIRCUIT BOARD LAYOUT
accuracy. The unique attributes of a zero drift amplifier provide a solution. Figure 84 shows a low-side current sensing circuit The ADA4522-1/ADA4522-2/ADA4522-4 are high precision using the ADA4522-1/ADA4522-2/ADA4522-4. The ADA4522-1/ devices with ultralow offset voltage and noise. Therefore, take ADA4522-2/ADA4522-4 are configured as difference amplifiers care in the design of the PCB layout to achieve optimum with a gain of 1000. Although the ADA4522-1/ADA4522-2/ performance of the ADA4522-1/ADA4522-2/ADA4522-4 at the ADA4522-4 have high CMRR, the CMRR of the system is limited board level. by the external resistors. Therefore, as mentioned in the Single- To avoid leakage currents, keep the surface of the board clean Supply Instrumentation Amplifier section, the key to high CMRR and free of moisture. for the system is resistors that are well matched from both the Properly bypassing the power supplies and keeping the supply resistive ratio and relative drift, where R1/R2 = R3/R4. traces short minimizes power supply disturbances caused by Any unused channel of the ADA4522-1/ADA4522-2/ADA4522-4 output current variation. Connect bypass capacitors as close must be configured in unity gain with the input common-mode as possible to the device supply pins. Stray capacitances are a voltage tied to the midpoint of the power supplies. concern at the outputs and the inputs of the amplifier. It is recommended that signal traces be kept at a distance of at least 5 mm from supply lines to minimize coupling. A potential source of offset error is the Seebeck voltage on the circuit board. The Seebeck voltage occurs at the junction of two dissimilar metals and is a function of the temperature of the junction. The most common metallic junctions on a circuit board are solder to board traces and solder to component leads. Figure 85 shows a cross section of a surface-mount component soldered to a PCB. A variation in temperature across the board (where TA1 ≠ TA2) causes a mismatch in the Seebeck voltages at the solder joints, thereby resulting in thermal voltage errors that degrade the Rev. F | Page 28 of 33 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONNECTION DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS—5.0 V OPERATION ELECTRICAL CHARACTERISTICS—30 V OPERATION ELECTRICAL CHARACTERISTICS—55 V OPERATION ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE POWER SEQUENCING ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION ON-CHIP INPUT EMI FILTER AND CLAMP CIRCUIT THERMAL SHUTDOWN INPUT PROTECTION SINGLE-SUPPLY AND RAIL-TO-RAIL OUTPUT LARGE SIGNAL TRANSIENT RESPONSE Case 1 Case 2 NOISE CONSIDERATIONS 1/f Noise Source Resistance Residual Ripple Current Noise Density EMI REJECTION RATIO CAPACITIVE LOAD STABILITY APPLICATIONS INFORMATION SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER LOAD CELL/STRAIN GAGE SENSOR SIGNAL CONDITIONING USING THE ADA4522-2 PRECISION LOW-SIDE CURRENT SHUNT SENSOR PRINTED CIRCUIT BOARD LAYOUT COMPARATOR OPERATION USE OF LARGE SOURCE RESISTANCE Unity Gain Follower with Large Source Resistance Workaround OUTLINE DIMENSIONS ORDERING GUIDE
ADA4522-1/ADA4522-2/ADA4522-4 Data Sheet +5V V+ ADA4522-2 100pF VDD 1/2 REF(+) DIN 1µF REF(–) DOUT/ 100pF RDY R1 11.3kΩ R3 C3 AD7791 1kΩ 1µF AIN(+) SCLK C1 3.3µF RG C5 V CS EXC 60.4Ω R4 10µF 1kΩ LOAD SENSE+ AIN(–) CELL C2 3.3µF C4 GND 1µF OUT– OUT+ R2 11.3kΩ SENSE– 1/2
79 0
ADA4522-2
8- 16 13 Figure 83. Precision Weigh Scale Measurement System
PRECISION LOW-SIDE CURRENT SHUNT SENSOR I
Many applications require the sensing of signals near the
V R SY I S RL
positive or negative rails. Current shunt sensors are one such
0.1Ω
application and are mostly used for feedback control systems.
R2 R1
They are also used in a variety of other applications, including
100kΩ 100Ω VOUT*
power metering, battery fuel gauging, and feedback controls in
ADA4522-1/ VSY
industrial applications. In such applications, it is desirable to
ADA4522-2/ ADA4522-4
use a shunt with very low resistance to minimize series voltage drop. This configuration not only minimizes wasted power, but also allows the measurement of high currents while saving power.
R4 R3 100kΩ 100Ω
A typical shunt may be 100 mΩ. At a measured current of 1 A, the voltage produced from the shunt is 100 mV, and the ampli-
*V
0
OUT = AMPLIFIER GAIN × VOLTAGE ACROSS RS
08
= 1000 × R
fier error sources are not critical. However, at low measured current
S × I
68-
= 100 × I
31 1 in the 1 mA range, the 100 μV generated across the shunt demands Figure 84. Low-Side Current Sensing Circuit a very low offset voltage and drift amplifier to maintain absolute
PRINTED CIRCUIT BOARD LAYOUT
accuracy. The unique attributes of a zero drift amplifier provide a solution. Figure 84 shows a low-side current sensing circuit The ADA4522-1/ADA4522-2/ADA4522-4 are high precision using the ADA4522-1/ADA4522-2/ADA4522-4. The ADA4522-1/ devices with ultralow offset voltage and noise. Therefore, take ADA4522-2/ADA4522-4 are configured as difference amplifiers care in the design of the PCB layout to achieve optimum with a gain of 1000. Although the ADA4522-1/ADA4522-2/ performance of the ADA4522-1/ADA4522-2/ADA4522-4 at the ADA4522-4 have high CMRR, the CMRR of the system is limited board level. by the external resistors. Therefore, as mentioned in the Single- To avoid leakage currents, keep the surface of the board clean Supply Instrumentation Amplifier section, the key to high CMRR and free of moisture. for the system is resistors that are well matched from both the Properly bypassing the power supplies and keeping the supply resistive ratio and relative drift, where R1/R2 = R3/R4. traces short minimizes power supply disturbances caused by Any unused channel of the ADA4522-1/ADA4522-2/ADA4522-4 output current variation. Connect bypass capacitors as close must be configured in unity gain with the input common-mode as possible to the device supply pins. Stray capacitances are a voltage tied to the midpoint of the power supplies. concern at the outputs and the inputs of the amplifier. It is recommended that signal traces be kept at a distance of at least 5 mm from supply lines to minimize coupling. A potential source of offset error is the Seebeck voltage on the circuit board. The Seebeck voltage occurs at the junction of two dissimilar metals and is a function of the temperature of the junction. The most common metallic junctions on a circuit board are solder to board traces and solder to component leads. Figure 85 shows a cross section of a surface-mount component soldered to a PCB. A variation in temperature across the board (where TA1 ≠ TA2) causes a mismatch in the Seebeck voltages at the solder joints, thereby resulting in thermal voltage errors that degrade the Rev. F | Page 28 of 33 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONNECTION DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS—5.0 V OPERATION ELECTRICAL CHARACTERISTICS—30 V OPERATION ELECTRICAL CHARACTERISTICS—55 V OPERATION ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE POWER SEQUENCING ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION ON-CHIP INPUT EMI FILTER AND CLAMP CIRCUIT THERMAL SHUTDOWN INPUT PROTECTION SINGLE-SUPPLY AND RAIL-TO-RAIL OUTPUT LARGE SIGNAL TRANSIENT RESPONSE Case 1 Case 2 NOISE CONSIDERATIONS 1/f Noise Source Resistance Residual Ripple Current Noise Density EMI REJECTION RATIO CAPACITIVE LOAD STABILITY APPLICATIONS INFORMATION SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER LOAD CELL/STRAIN GAGE SENSOR SIGNAL CONDITIONING USING THE ADA4522-2 PRECISION LOW-SIDE CURRENT SHUNT SENSOR PRINTED CIRCUIT BOARD LAYOUT COMPARATOR OPERATION USE OF LARGE SOURCE RESISTANCE Unity Gain Follower with Large Source Resistance Workaround OUTLINE DIMENSIONS ORDERING GUIDE
