Analog Input Features - Keithley DAS-8 Series User Manual

Ch 0
Analog In
8 Channels
MUX
Ch 7
Gain Control
Channel Select
& Scan Logic DAS-8/PGA(G2)
Internal Data Bus
Digital I/O
IP1
IP2
Control
IP3
I/O
Registers
Buffers
OP1
Status
OP2
Registers
OP3
OP4
+5V
+12V
-12V
COM
Bus Power for
Expansion & Interface
Figure 2-1. DAS-8 Series Functional Block Diagram

Analog Input Features

DAS-8 Series boards use a 12-bit, successive approximation
analog-to-digital converter (ADC) with integral sample and hold. The
ADC provides 12-bit resolution ±1 least significant bit (LSB), providing
an effective accuracy of 11 bits. The ADC converts one sample every
µ µ
25 s (25 s max.), providing an average conversion frequency of more
than 4 kHz (machine and software dependent).
2-2
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12 Bit A/D
with
Sample/Hold
Clock Generate
Conversion
& Control Logic
Control Logic
Timer/
Counter
Clk 2
Gate 2
Out 2
Clk 1
Gate 1
Out 1
Clk 0
Gate 0
Out 0
Interrupt
Control
Address
Decode &
Bus Interface
Interrupt Select
Levels 2-7
(Jumper)
IBM PC AT Bus
Clk 1
Gate 1
Gate 2
Out 1
Out 2
Gate 0
Clk 0
Out 0
INT_IN
Functional Description