Introduction; Overall Functional Description - Fluke 8020A Instruction Manual

3-1.

INTRODUCTION

3-2. This section of the manual contains an overall
functional description followed by a block diagram
analysis of the 8020A. A detailed schematic of the
3-3. OVERALL FUNCTIONAL
DESCRIPTION
3-4. The Model 8020A, as shown in Figure 3-1, is a
hand-held six function digital multimeter. It features a
total of 26 measurement ranges (V dc, 5; V ac, 5; ohms,
6; conductance, 2; mA dc, 4; and mA ac, 4), a high
COMM RANGE
SWITCHES
VOLTAGE
V
DIVIDER
SWITCHES
OHMS
CONVERTER
AC
CONVERTER
CURRENT
SHUNTS
SIGNAL
CONDITIONERS
Flgure 3-1. 8020A Slmpllfled Block Diagram
Theory of Operation
contrast easy-to-read, 3-112 digit, liquid crystal display;
long battery life (up to 200 hours); overload protection
for all ranges; and a minimum of components.
3-5. Operation centers around a custom LSI chip,
display driver. Peripherals to U8 include range and
function switches, input signal conditioners, and the
display., When an input signal is applied to the 8020A, it
is routed through the range switches to one-of-four
input signal conditioners as determined by the function
switch setting. Each conditioner scales and, if necessary,
rectifies the input so that an acceptable dc input level
(-0.2 to +0.2V dc) is presented to the a / d converter.
7 - - - - - -
7
Vdc
RANGE
OR
FUNCTION
SWITCHES
Section 3
DC
A I D
ANALOG
CONVERTER
D A T A
A N D
DISPLAY
DRIVER
DECIMAL
DISPLAY
POINT
3-1