Datasheet AD620 (Analog Devices) - 14
| Manufacturer | Analog Devices |
| Description | Low Cost Low Power Instrumentation Amplifier |
| Pages / Page | 20 / 14 — AD620. 20k. REF. G = 100. AD620B. DIGITAL. 499. 10k. ADC. DATA. OUTPUT. … |
| Revision | H |
| File Format / Size | PDF / 427 Kb |
| Document Language | English |
AD620. 20k. REF. G = 100. AD620B. DIGITAL. 499. 10k. ADC. DATA. OUTPUT. AD705. AGND. 0.6mA. 1.7mA. 1.3mA. 0.10mA. MAX. Pressure Measurement. Medical ECG. +3V
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Text Version of Document
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AD620 5V 20k
Ω
7 3 3k
Ω
3k
Ω
REF 8 G = 100 AD620B 6 IN DIGITAL 499
Ω
3k
Ω
3k
Ω
5 10k
Ω
1 ADC DATA OUTPUT 2 4 AD705 AGND 20k
Ω
0.6mA 1.7mA 1.3mA 0.10mA MAX MAX
00775-0-042 Figure 38. A Pressure Monitor Circuit that Operates on a 5 V Single Supply
Pressure Measurement Medical ECG
Although useful in many bridge applications, such as weigh The low current noise of the AD620 allows its use in ECG scales, the AD620 is especially suitable for higher resistance monitors (Figure 39) where high source resistances of 1 MΩ or pressure sensors powered at lower voltages where small size and higher are not uncommon. The AD620’s low power, low supply low power become more significant. voltage requirements, and space-saving 8-lead mini-DIP and SOIC package offerings make it an excellent choice for battery- Figure 38 shows a 3 kΩ pressure transducer bridge powered powered data recorders. from 5 V. In such a circuit, the bridge consumes only 1.7 mA. Adding the AD620 and a buffered voltage divider allows the Furthermore, the low bias currents and low current noise, signal to be conditioned for only 3.8 mA of total supply current. coupled with the low voltage noise of the AD620, improve the dynamic range for better performance. Small size and low cost make the AD620 especially attractive for voltage output pressure transducers. Since it delivers low noise The value of capacitor C1 is chosen to maintain stability of and drift, it also serves applications such as diagnostic the right leg drive loop. Proper safeguards, such as isolation, noninvasive blood pressure measurement. must be added to this circuit to protect the patient from possible harm.
+3V PATIENT/CIRCUIT PROTECTION/ISOLATION R1 R3 0.03Hz C1 10k
Ω
24.9k
Ω
RG AD620A HIGH- OUTPUT 8.25k
Ω
PASS G = 143 1V/mV R4 R2 G = 7 FILTER 1M
Ω
24.9k
Ω
OUTPUT AMPLIFIER AD705J –3V
00775-0-043 Figure 39. A Medical ECG Monitor Circuit Rev. H | Page 14 of 20 Document Outline SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION Make vs. Buy: a Typical Bridge Application Error Budget Pressure Measurement Medical ECG Precision V-I Converter GAIN SELECTION INPUT AND OUTPUT OFFSET VOLTAGE REFERENCE TERMINAL INPUT PROTECTION RF INTERFERENCE COMMON-MODE REJECTION GROUNDING GROUND RETURNS FOR INPUT BIAS CURRENTS AD620ACHIPS INFORMATION OUTLINE DIMENSIONS ORDERING GUIDE
AD620 5V 20k
Ω
7 3 3k
Ω
3k
Ω
REF 8 G = 100 AD620B 6 IN DIGITAL 499
Ω
3k
Ω
3k
Ω
5 10k
Ω
1 ADC DATA OUTPUT 2 4 AD705 AGND 20k
Ω
0.6mA 1.7mA 1.3mA 0.10mA MAX MAX
00775-0-042 Figure 38. A Pressure Monitor Circuit that Operates on a 5 V Single Supply
Pressure Measurement Medical ECG
Although useful in many bridge applications, such as weigh The low current noise of the AD620 allows its use in ECG scales, the AD620 is especially suitable for higher resistance monitors (Figure 39) where high source resistances of 1 MΩ or pressure sensors powered at lower voltages where small size and higher are not uncommon. The AD620’s low power, low supply low power become more significant. voltage requirements, and space-saving 8-lead mini-DIP and SOIC package offerings make it an excellent choice for battery- Figure 38 shows a 3 kΩ pressure transducer bridge powered powered data recorders. from 5 V. In such a circuit, the bridge consumes only 1.7 mA. Adding the AD620 and a buffered voltage divider allows the Furthermore, the low bias currents and low current noise, signal to be conditioned for only 3.8 mA of total supply current. coupled with the low voltage noise of the AD620, improve the dynamic range for better performance. Small size and low cost make the AD620 especially attractive for voltage output pressure transducers. Since it delivers low noise The value of capacitor C1 is chosen to maintain stability of and drift, it also serves applications such as diagnostic the right leg drive loop. Proper safeguards, such as isolation, noninvasive blood pressure measurement. must be added to this circuit to protect the patient from possible harm.
+3V PATIENT/CIRCUIT PROTECTION/ISOLATION R1 R3 0.03Hz C1 10k
Ω
24.9k
Ω
RG AD620A HIGH- OUTPUT 8.25k
Ω
PASS G = 143 1V/mV R4 R2 G = 7 FILTER 1M
Ω
24.9k
Ω
OUTPUT AMPLIFIER AD705J –3V
00775-0-043 Figure 39. A Medical ECG Monitor Circuit Rev. H | Page 14 of 20 Document Outline SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION Make vs. Buy: a Typical Bridge Application Error Budget Pressure Measurement Medical ECG Precision V-I Converter GAIN SELECTION INPUT AND OUTPUT OFFSET VOLTAGE REFERENCE TERMINAL INPUT PROTECTION RF INTERFERENCE COMMON-MODE REJECTION GROUNDING GROUND RETURNS FOR INPUT BIAS CURRENTS AD620ACHIPS INFORMATION OUTLINE DIMENSIONS ORDERING GUIDE
