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
•
•
•
•
•
•
•
•
•
•
Applications
•
•
•
•
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
1
AGND
Comparator
2
Internal CS
Input Latch
Mux Select
Start Conv
Vcc
WM0834
4 Inputs
Input
MUX
DAC
&
SAR
Logic
Control
Logic
SE
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
WM0834, WM0838
Pin Configuration
Top View
WM0834 : N(DIP) and D (SO) packages
WM0838: N(DIP) and DW (SO) packages
Ordering Information
5V devices
DEVICE
WM0834CN
WM0834CD
WM0834IN
WM0834ID
WM0838CN
WM0838CDW
WM0838IN
WM0838IDW
3.3V devices
DEVICE
WM0834LCN
WM0834LCD
WM0834LIN
WM0834LID
WM0838LCN
WM0838LCDW
WM0838LIN
WM0838LIDW
TEMP. RANGE
0
o
C to 70
o
C
0
o
C to 70
o
C
-40
o
C to 85
o
C
-40
o
C to 85
o
C
0
o
C to 70
o
C
0
o
C to 70
o
C
-40
o
C to 85
o
C
-40
o
C to 85
o
C
PACKAGE
14 pin plastic DIP
14 pin plastic SO
14 pin plastic DIP
14 pin plastic SO
20 pin plastic DIP
20 pin plastic SO
20 pin plastic DIP
20 pin plastic SO
TEMP. RANGE
0
o
C to 70
o
C
0
o
C to 70
o
C
-40
o
C to 85
o
C
-40
o
C to 85
o
C
0
o
C to 70
o
C
0
o
C to 70
o
C
-40
o
C to 85
o
C
-40
o
C to 85
o
C
PACKAGE
14 pin plastic DIP
14 pin plastic SO
14 pin plastic DIP
14 pin plastic SO
20 pin plastic DIP
20 pin plastic SO
20 pin plastic DIP
20 pin plastic SO
WM0834
WM0838
Absolute Maximum Ratings
(note 1)
Supply Voltage, Vcc (note 2) . . . . . . . . . . . 6.5 V
Input voltage range:
Digital Inputs . . . . GND - 0.3 V, VCC + 0.3 V
Analogue inputs . . . GND - 0.3 V, VCC + 0.3 V
Input current, any pin (note 3) . . . . . . ± 5 mA
Total Input current for package . . . . . . ± 20 mA
Operating temperature range, TA . . . . TMIN to TMAX
WM083_C_ (C suffix) . . . . . . . . . 0
o
C to +70
o
C
WM083_I_ (I suffix) . . . . . . . . . . -40
o
C to +85
o
C
Storage Temperature . . . . . . . . - 65
o
C to +150
o
C
Soldering Information:
Lead Temperature 1.6 mm (1/16) from case
for 10 seconds: D, DW or N package . . . . . . . 260
o
C
Recommended Operating Conditions (5V)
Supply voltage
High level input voltage
Low level input voltage
Clock frequency
Clock duty cycle (see Note 4)
Pulse duration CS high
Operating free-air temperature
SYMBOL
V
CC
V
IH
V
IL
f
clock
D
clk
t
wH(CS)
T
A
T
A
MIN
4.5
2
10
40
220
0
-40
70
85
NOMINAL
5
MAX
5.5
0.8
600
60
UNIT
V
V
V
KHz
%
ns
o
C
C suffix
I Suffix
Wolfson Microelectronics
2
WM0834, WM0838
Electrical Characteristics
(5V)
V
CC
= 5.0V, V
REF
= 5V, f
CLK
= 250 KHz, T
A
= T
MIN
to T
MAX
, tr = tf = 20ns, unless otherwise stated.
PARAMETER
Digital Inputs
High level output voltage
Low level output voltage
High level input current
Low level input current
High level output (source)
current
Low level output (sink) current
High impedance-state
output current (DO)
Input capacitance
Output capacitance
Converter and Multiplexer
Total unadjusted error
Differential Linearity
Supply voltage variation error
Common mode error
Common mode input voltage
range
Standby input leakage
current (note 10)
SYMBOL
V
OH
V
OL
I
IH
I
IL
I
OH
I
OL
I
OZ
C
i
C
o
TUE
V
s(error)
V
ICR
I
I(stdby)
V
REF
= 5 V. (note 7)
(note 8)
V
CC
= 4.75 V to 5.25 V
Differential mode
(note 9)
On-channel VI = 5 V at ON ch.
Off-channel VI = 0 V at OFF ch.
On-channel VI = 0 V at ON ch.
Off-channel VI = 5 V at OFF ch.
Excluding MUX addressing time
TEST CONDITIONS
V
CC
= 4.75 V, I
OH
= -360 mA
V
CC
= 4.75 V, I
OH
= -10 mA
V
CC
= 5.25 V, I
OH
= 1.6 mA
V
IH
= 5 V
V
IL
= 0 V
V
OH
= 0 V
V
OL
= V
CC
V
O
= 5 V
V
O
= 0 V
MIN
2.4
4.5
0.005
-0.005
-24
26
0.01
-0.01
5
5
0.4
1
-1
TYP
MAX
UNIT
V
V
V
µA
µA
mA
mA
µA
µA
pF
pF
LSB
Bits
LSB
LSB
V
µA
µA
µA
µA
clock
periods
kΩ
-6.5
8
3
-3
±1
8
±1/16
±1/16
GND-0.05
V
CC
+0.05
1
-1
-1
1
8
±1/4
±1/4
Conversion time
Reference Inputs
Input resistance to
reference ladder
Total device
Supply current
Timing Parameters
Setup time, CS low or
data valid before clock
Hold time, data valid after
clock
Propagation delay time,
output data after clock
Output disable time, DO
after CS
tconv
R
i(REF)
1.3
2.4
5.9
I
CC
t
su
t
h
MSB data first.
C
L
= 100 pF
LSB data first.
C
L
= 100 pF
C
L
= 10 pF, R
L
= 10 kΩ
CL = 100 pF, R
L
= 2 kΩ
350
90
0.6
1.25
mA
ns
ns
t
pd
t
dis
125
1500
600
250
500
ns
ns
ns
ns
Wolfson Microelectronics
3
WM0834, WM0838
Electrical Characteristics
(3.3V)
V
CC
= 3.3V, f
CLK
= 250 KHz, T
A
= T
MIN
to T
MAX
, tr = tf = 20ns, unless otherwise stated.
PARAMETER
Digital Inputs
High level output voltage
Low level output voltage
High level input current
Low level input current
High level output (source)
current
Low level output (sink) current
High impedance-state
output current (DO)
Input capacitance
Output capacitance
Converter and Multiplexer
Total unadjusted error
Differential Linearity
Supply voltage variation error
Common mode error
Common mode input voltage
range
Standby input leakage
current (note 10)
SYMBOL
V
OH
V
OL
I
IH
I
IL
I
OH
I
OL
I
OZ
C
i
C
o
TUE
V
s(error)
V
ICR
I
I(stdby)
V
REF
= 3.3 V. (note 7)
(note 8)
V
CC
= 3.0 V to 3.6 V
Differential mode
(note 9)
On-channel VI =3.3 V at ON ch.
Off-channel VI = 0 V at OFF ch.
On-channel VI = 0 V at ON ch.
Off-channel VI =3.3V at OFF ch
Excluding MUX addressing time
TEST CONDITIONS
V
CC
= 3.0 V, I
OH
= -360 mA
V
CC
= 3.0V, I
OH
= -10 mA
V
CC
=3.0V, I
OH
= 1.6 mA
V
IH
= 3.6V
V
IL
= 0 V
V
OH
= 0 V, T
A
= 25
o
C
V
OL
= V
CC
, T
A
= 25
o
C
V
O
= 3.3 V, T
A
= 25
o
C
V
O
= 0 V, T
A
= 25
o
C
MIN
2.4
2.8
0.005
-0.005
15
16
0.01
-0.01
5
5
0.4
1
-1
TYP
MAX
UNIT
V
V
V
µA
µA
mA
mA
µA
µA
pF
pF
LSB
Bits
LSB
LSB
V
µA
µA
µA
µA
clock
periods
kΩ
6.5
8
3
-3
±1
8
±1/16
±1/16
GND-0.05
V
CC
+0.05
1
-1
-1
1
8
±1/4
±1/4
Conversion time
Reference Inputs
Input resistance to
reference ladder
Total device
Supply current
Timing Parameters
Setup time, CS low or
data valid before clock
Hold time, data valid after
clock
Propagation delay time,
output data after clock
Output disable time, DO
after CS
tconv
R
i(REF)
1.3
2.4
5.9
I
CC
t
su
t
h
MSB data first.
C
L
= 100 pF
LSB data first.
C
L
= 100 pF
C
L
= 10 pF, R
L
= 10 kΩ
CL = 100 pF, R
L
= 2 kΩ
350
90
0.2
0.75
mA
ns
ns
t
pd
t
dis
500
200
80
250
ns
ns
ns
ns
Wolfson Microelectronics
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