DATASHEET
HI-7159A
FN2936
Rev 4.00
January 1999
Microprocessor-Compatible, 5-1/2 Digit A/D Converter
The Intersil HI-7159A is a monolithic A/D converter that uses
a unique dual slope technique which allows it to resolve input
changes as small as 1 part in 200,000 (10V) without the use
of critical external components. Its digital autozeroing feature
virtually eliminates zero drift over temperature. The device is
fabricated in Intersil’ proprietary low noise BiMOS process,
resulting in exceptional linearity and noise performance. The
HI-7159A’s resolution can be switched between a high
resolution 200,000 count (51/2 digit) mode, and a high speed
20,000 count (41/2 digit) mode without any hardware
modifications. In the 41/2 digit uncompensated mode, speeds
of 60 conversions per second can be achieved. The HI-7159A
is designed to be easily interfaced with most microprocessors
through either of its three serial and one parallel interface
modes. In the serial modes, any one of four common baud
rates is available.
Features
Ordering Information
• Weigh Scales
PART NUMBER
HI3-7159A-5
TEMP.
RANGE (oC)
0 to 70
• 2V Full Scale Reading With 10V Resolution
• 15 Conversions Per Second in 51/2 Digit Mode
• 60 Conversions Per Second in 41/2 Digit Mode
• Serial or Parallel Interface Modes
• Four Selectable Baud Rates
• Differential Analog Input
• Differential Reference Input
• Digital Autozero
Applications
• Part Counting Scales
PKG.
NO.
PACKAGE
28 Ld PDIP
• 200,000 Count A/D Converter
• Laboratory Instruments
E28.6
• Process Control/Monitoring
• Energy Management
• Seismic Monitoring
Pinout
Functional Block Diagram
HI-7159A
(PDIP)
TOP VIEW
AGND
INT IN 3
BUF OUT
CREFGUARD
CREFCREF+
XTAL
DGND
28 SEL
27 XTAL
26 DGND
4
5
24 P6/BRS0
6
INTEGRATOR
-
22 P4/SAD2
COMPARATOR
+
+
23 P5/SAD3
7
CINT
25 P7/BRS1
CREF+
8
GUARD
VREF HI 9
VCC
-
CONTROL
SECTION
AND
LATCHES
RINT
BUFFER
CS
+
-
21 P3/SAD1
VREF HI
20 P2/SAD0
VREF LO
VREF LO 10
19 P1/SMS1
VIN HI
AGND 11
18 P0/SMS0
VIN LO
VIN HI 12
17 CS/SAD4
CREF
VIN LO 13
WR
RD
16 WR/TXD
VEE 14
8 BIT
BUS
BUS
INTERFACE
UNIT
I/O PORTS
VCC 1
INT OUT 2
VEE
15 RD/RXD
FN2936 Rev 4.00
January 1999
UART
ANALOG SWITCHES
ANALOG
STATE
MACHINE
SEL
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