AB Amps 105 Bedienungsanleitung

DEAD BAND CIRCUITS USING CURRENT REFERENCE ... 14BIDIRECTIONAL CURRENT SOURCES ...16LIMITING CIRCUITS USINGBIDIRE

10Since the gate of the JFET is tied to ground, the outputcompliance is limited to near ground. If greater complianceis required for the current sink,

11200µA Floating CascodedCurrent Source Using REF200Floating cascoded current sources with typical output im-pedances exceeding 10GΩ can be easily imp

12The value of the resistor used in the noise reduction circuitdetermines its ultimate performance. Although the noise ofthe resistor increases with t

13FIGURE 33. 100µV Reference for VFC off-zeroing.FIGURE 34. Buffered Voltage Reference.For a floating voltage reference, simply drive the referencelow

14FIGURE 35. Op Amp Offset Adjustment Circuit uses the two 100µA current sources from a REF200 to provide accurate ±5mVreferences.FIGURE 36. Op amp o

15WINDOW COMPARATOR USINGFLOATING VOLTAGE REFERENCEThe window comparator circuit, Figure 37, is an example ofa floating reference application. Here, a

16FIGURE 38. RTD excitation with three-wire lead resistance compensation.FIGURE 39. Precision positive dead-band circuit.DEAD BAND CIRCUITSUSING CURRE

17FIGURE 41. Precision double dead-band circuit.FIGURE 40. Precision negative dead-band circuit.

18BIDIRECTIONAL CURRENT SOURCESOne of the advantages in working with currents is that theycan be steered by diodes or switches without error. As longa

19If a limit in just one direction is required, replace thebidirectional current source with a current source and singlediode as shown in Figure 45. F

2DESIGN OF FIXEDCURRENT SOURCESREF200 IC CURRENT SOURCE DESCRIPTIONThe REF200 dual current source has two current sourcesplus a current mirror in an 8

20ment is critical. While single supply op amps have beenavailable for many years, single supply IAs have not. What’smore, single supply IAs can not b

21Use of this circuit was limited in the past due to the criticalresistor matching and resistor TCR tracking requirements.By using the INA105 differen

22You need an extra amplifier to drive the feedback resistor inthe difference amplifier, but only one external resistor isrequired, and no matching or

23FIGURE 53. Temperature-controlled current source using XTR101.FIGURE 54. Precision single-supply voltage-to-current source transmitter—the XTR110.

24Matching resistor, RM, preserves the resistance match of theINA105 and maintains its high common-mode rejection(CMR). Because 100Ω is small compared

25FIGURE 56. Bridge amplifier load current monitor using the INA117.To understand how the circuit works, notice that since nocurrent flows into the in

26FIGURE 58. Virtual ground current-to-voltage converter.FIGURE 59. Virtual ground current-to-voltage converterredrawn to Illustrate phase delay due t

27FIGURE 60A. Standard Transimpedance Amplifier withcapacitor divider and added feedback pole.FIGURE 62. Transimpedance signal response of standardand

28FIGURES 64 and 65. Photodiode amplifier using floatingvirtual ground current-to-voltageconverter.FIGURE 63. Noise gain of standard and improvedphoto

29GLOSSARYABBREVIATIONS, DEFINITIONSBidirectional Current Source—A floating current sourcethat provides a constant current independent of the polarity

3PIN STRAPPING REF200 FOR:50µA CURRENT SINKWith a 100µA current source as a reference, it is simple toconstruct a current source of any value. The REF

IMPORTANT NOTICETexas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinueany product or servic

4FIGURE 8. For a 200µA Floating Current Source simplyparallel the two 100µA current sources from theREF200.FIGURE 10. The two 100µA Current Sources an

5FIGURE 15. Current Sink.Current Source or Sink With Any Current OutFor currents less than 100µA, use the circuits shown inFigures 14 and 15. They can

6FIGURE 15A. Current Source using Voltage Reference and Op Amp.FIGURE 15B. Current Sink using Voltage Reference and Op Amp.Make a current source from

7Floating Current SourceWith Current Out > 100µAIf a completely floating programable current source is needed,use the circuit shown in Figure 16. I

8FIGURE 17. Programmable Current Sink using series pass device.FIGURE 18. Sinking Current Mirror using series pass device.NOTE: Can be connected to –V

9NOTE: The LF155 input common-mode range typically includes +VS,but this is not a guaranteed specification.quiescent current flowing from its negative