WM0834, WM0838
Production Data
Sept 1996 Rev 2.0
8-Bit ADCs with Serial Interface and
Configurable Input Multiplexer
Description
WM0834 and WM0838 are 8-bit analogue to digital
converters (ADC) with configurable 4-input and 8-input
multiplexers respectively and a serial I/O interface.
Assignment of the multiplexer inputs is configured before
each conversion via the serial data input to give single-ended
or differential operation for the selected inputs. A mixture of
input configurations can be used in the same application.
WM0838 also has a pseudo-differential configuration where
all 8 inputs can be refered to a common input at an arbitrary
voltage.
Serial communcation with WM0834/8 is via Data In (DI) and
Data Out (DO) wires under the control of clock and chip
select inputs. A high output at the SARS pin indicates when
the conversion is in progress. To initiate a conversion chip
enable is held low and data is input to DI on the rising edge
of the clock, comprising, a start bit, and bits to set up the
input configuration and polarity. After a half clock cycle delay
conversion results appear at DO on the falling edge of the
clock, MSB first, concurrently with A-D conversion. This is
followed by the results LSB first, indicated by the falling edge
of SARS. WM0838 has a shift enable (SE) input used to
control the LSB first output on DO.
WM0834/8 operate on 5V and 3.3V supply voltages and
are available in small outline and DIP packages for com-
mercial (0 to 70
O
C) and industrial (-40 to 85
O
C) tempera-
ture ranges.
Features
•
Functionally Equivalent to National Semiconduc-
tor ADC0834 and ADC0838 without the Internal
Zener Regulator Network
4-input (WM0834) or 8-input (WM0838) MUX
options
Reference input operates ratiometrically or with
a fixed reference
Input range 0 to Vcc with Vcc Reference
5V and 3.3V variants
Total Unadjusted Error:
±
1 LSB
8-bit resolution
Low Power
32
µ
s conversion time at fclock = 250 kHz
Serial I/O interface
WM0834 packages: 14 pin SO & DIP
WM0838 packages: 20 pin wide-body SO & DIP
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Applications
•
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Embedding with remote sensors
Equipment health monitoring
Automotive
Industrial control
Block Diagram
CS
CLK
DI
V
REF
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
AGND
1
Internal CS
Input Latch
Mux Select
Start Conv
Vcc
Comparator
WM0834
4 Inputs
Input
MUX
DAC
&
SAR
Logic
Control
Logic
SE
2
SARS
WM0838
8 Inputs
Output Shift
Register
DO
DGND
WM0834/8
Notes:
1. Internally tied to AGND for WM0834
2. Not available on WM0834
Production Data
data sheets contain final
specifications current on publication date. Supply
of products conforms to Wolfson Microelectronics
standard terms and conditions.
Wolfson Microelectronics
Lutton Court, Bernard Terrace, Edinburgh EH8 9NX, UK
© 1996 Wolfson Microelectronics
Tel: +44 (0) 131 667 9386
Fax: +44 (0) 131 667 5176
email: admin@wolfson.co.uk
www: http://www.wolfson.co.uk
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
