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Each analog-to-digital conversion begins when the multimeter is
triggered. The ADC starts by clearing the integrator slope count in
A1U209. At the end of the integration period, the slope count is
latched. The slope count provides the most significant bits of the
input voltage conversion. The least significant bits are converted by
the on-chip ADC of CPU A1U205.
The instrument precision voltage reference is U403. Resistor R409
provides a stable bias current for the reference zener diode. R408
and CR404 provide a bias to assure that the reference zener biases to
+7 V during power up. IC U400A amplifies the voltage reference to
+10 V while amplifier U401A inverts the +10 V reference to –10 V.
The reference voltages force precision slope currents for the
integrating ADC through U102E–R17, R18.
5
Chapter 5 Theory of Operation
Internal DMM
137
Содержание 34970A
Страница 1: ...Agilent 34970A Data Acquisition Switch Unit Service Guide ...
Страница 34: ...32 ...
Страница 35: ...2 Quick Start 2 ...
Страница 49: ...3 Front Panel Overview 3 ...
Страница 62: ...60 ...
Страница 63: ...4 Calibration Procedures 4 ...
Страница 118: ...116 ...
Страница 119: ...5 Theory of Operation 5 ...
Страница 159: ...6 Service 6 ...
Страница 177: ...General Disassembly 4 3 2 1 6 Chapter 6 Service Disassembly 175 ...
Страница 178: ...Internal DMM Disassembly 3 2 1 Chapter 6 Service Disassembly 176 ...
Страница 180: ...Additional Chassis Disassembly 1 2 Chapter 6 Service Disassembly 178 ...
Страница 181: ...Plug In Module Disassembly Needle nose Pliers 6 Chapter 6 Service Disassembly 179 ...
Страница 182: ...180 ...
Страница 183: ...7 Replaceable Parts 7 ...
Страница 220: ...Chapter 7 Replaceable Parts Manufacturer s List 218 ...
Страница 221: ...8 Schematics 8 ...
Страница 272: ......