Fluke 867B - Block Diagram

Theory of Operation
Power Supply
2
2-5
Volts/ohms
Protection
COM
mA/uA
AMPS
Current
Switching
SHUNTS
DC Filter
SWCrtl1
Multiplexer
4 1/2 Digit
A/D
SWCtrl6
U10
Flash A/D
8 bit/10 Mhz
uA
mA/A
DC Input
Attenuation
SWCrtl0
AC Input Attenuation
& x10 gain
ACR1-4
Ohms/
Capacitance
Source
SWCtrl3
Multiplexer
IR1
Component
Test
Current to
Voltage
Trigger
Circuitry
DC Level
(Comp.
Te st
DAC)
2 Frequency Counters
(25 bits)
U3 RMS
Converter
Min
Max
CompareCompare
Acq. Ram
512 x 8
Acquisition Cnt.
(Trigger) Circuit
Data
Addr
Divide by
Circuitry
Reference Counter
(25 bits)
CLK
Status and Control Regs
U25
MICROPROCESSOR
H8
Data
Addr
U11, U19 ROM
2 128 x 8
U20 SRAM
32k x 8 System
U13 LCD Controller
1335
LCD Module - Drivers,
240 x200, Backlight
UART
SWCrtl10
To/From uProcessor
To /F ro m
RIC
SWControl
RIC Function Blocks - U30
DIC Function Blocks - U24
To/F r om
RS-232
4.8 MHz
ADControl
ADControl
SWCrtl13
Component Test Source
DAC1
DACL1
Rotary
Switch
Wakeup* to Power Supply
DACData
Keyboard
Module
EEPROM
Logic Activity/ External Trigger
Attenuation
I/O
INT1
I/O
Component Test
Power Supply
-5.2 volts
3.27 volts
LCD
Voltage VEE
BATTLVL To uProcessor A/D
To uProcessor A/D
5.2 volts
POWER_DOWN* From uProcessor
Volts/Ohms/Current
Filter
LCD Contrast
Adjust
Combination/
x1/10,x1,x10
Circuit
Dual
Comparators
DAC2
DACL2
DACL1
DACL2
Logic Activity/
External
Trigger
BATTELIM To u P r o c e s s o r A/ D
BATTTYPE To uProcessor A/D
U11
10Bit DAC
U21 SRAM 32 x 8
Dsiplay
os2f..eps
Figure 2-1. Block Diagram