Datasheet AD549 (Analog Devices) - 7

Data Sheet AD549 3000 50 45 V) /m 1000 V fA) 40 ( ( IN NT A 35 P G O O CURRE -L UT 300 30 PEN INP O 25
08 11 0 0 1- 1-
100
051 051 0
20
0
–55 –25 5 35 65 95 125 0 5 10 15 20 TEMPERATURE (°C) POWER SUPPLY VOLTAGE (±V)
Figure 8. Open-Loop Gain vs. Temperature Figure 11. Input Bias Current vs. Power Supply Voltage
30 160 ) 140 25 / Hz V 120 (n 20 Y IT ) V µ NS 100 I ( 15 DE OSIV 80 RAL ∆ CT 10 E P 60 S E IS 5 NO 40
09 12 0 0 1- 1-
0
051 051 0
20
0
0 1 2 3 4 5 6 7 10 100 1k 10k WARM-UP TIME (Minutes) FREQUENCY (Hz)
Figure 9. Change in Offset Voltage vs. Warm-Up Time Figure 12. Input Voltage Noise Spectral Density
50 100k WHENEVER JOHNSON NOISE IS GREATER THAN AMPLIFIER NOISE, AMPLIFIER NOISE CAN BE CONSIDERED NEGLIGIBLE FOR THE APPLICATION 45 10k ) -p 1kHz BANDWIDTH p V RESISTOR fA) 40 (µ 1k JOHNSON NOISE ( E G NT A T 35 L 100 CURRE UT ISE VO 30 O 10 INP N T PU 10Hz BANDWIDTH 25 IN 1
0 3 -01 -01
AMPLIFIER GENERATED NOISE
1 1 51 51
20
00
0.1
00
–10 –5 0 5 10 100k 1M 10M 100M 1G 10G 100G COMMON-MODE VOLTAGE (V) SOURCE RESISTANCE (Ω)
Figure 10. Input Bias Current vs. Common-Mode Voltage Figure 13. Noise vs. Source Resistance Rev. K | Page 7 of 18 Document Outline FEATURES APPLICATIONS CONNECTION DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS FUNCTIONAL DESCRIPTION MINIMIZING INPUT CURRENT CIRCUIT BOARD NOTES OFFSET NULLING AC RESPONSE WITH HIGH VALUE SOURCE AND FEEDBACK RESISTANCE COMMON-MODE INPUT VOLTAGE OVERLOAD DIFFERENTIAL INPUT VOLTAGE OVERLOAD INPUT PROTECTION SAMPLE-AND-DIFFERENCE CIRCUIT TO MEASURE ELECTROMETER LEAKAGE CURRENTS PHOTODIODE INTERFACE Photodiode Preamp Noise LOG RATIO AMPLIFIER TEMPERATURE COMPENSATED pH PROBE AMPLIFIER OUTLINE DIMENSIONS ORDERING GUIDE