Block Diagram
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Wolfson Microelectronics
Production Data data sheets contain final
specifications current on publication date. Supply
of products conforms to Wolfson Microelectronics
standard terms and conditions.
1996 Wolfson Microelectronics
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
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
CH0
CH1
CH2
CH3
CH4
CH5
CH6
CH7
COM
1
AGND
V
REF
DI
CLK
CS
Notes:
1. Internally tied to AGND for WM0834
2. Not available on WM0834
WM0834
4 Inputs
WM0838
8 Inputs
DO
SARS
DGND
SE
2
Vcc
Input
MUX
Control
Logic
Output Shift
Register
Comparator
Start Conv
Mux Select
WM0834/8
DAC
&
SAR
Logic
Input Latch
Internal CS
Wolfson Microelectronics
2
WM0834, WM0838
Ordering Information
Pin Configuration
Top View
WM0834 : N(DIP) and D (SO) packages
WM0838: N(DIP) and DW (SO) packages
DEVICE
TEMP. RANGE
PACKAGE
WM0834CN
0
o
C to 70
o
C
14 pin plastic DIP
WM0834CD
0
o
C to 70
o
C
14 pin plastic SO
WM0834IN
-40
o
C to 85
o
C
14 pin plastic DIP
WM0834ID
-40
o
C to 85
o
C
14 pin plastic SO
WM0838CN
0
o
C to 70
o
C
20 pin plastic DIP
WM0838CDW
0
o
C to 70
o
C
20 pin plastic SO
WM0838IN
-40
o
C to 85
o
C
20 pin plastic DIP
WM0838IDW
-40
o
C to 85
o
C
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)
SYMBOL MIN NOMINAL MAX UNIT
Supply voltage
V
CC
4.5
5
5.5
V
High level input voltage
V
IH
2
V
Low level input voltage
V
IL
0.8
V
Clock frequency
f
clock
10
600
KHz
Clock duty cycle (see Note 4)
D
clk
40
60
%
Pulse duration CS high
t
wH(CS)
220
ns
Operating free-air temperature
C suffix
T
A
0
70
o
C
I Suffix
T
A
-40
85
DEVICE
TEMP. RANGE
PACKAGE
WM0834LCN
0
o
C to 70
o
C
14 pin plastic DIP
WM0834LCD
0
o
C to 70
o
C
14 pin plastic SO
WM0834LIN
-40
o
C to 85
o
C
14 pin plastic DIP
WM0834LID
-40
o
C to 85
o
C
14 pin plastic SO
WM0838LCN
0
o
C to 70
o
C
20 pin plastic DIP
WM0838LCDW
0
o
C to 70
o
C
20 pin plastic SO
WM0838LIN
-40
o
C to 85
o
C
20 pin plastic DIP
WM0838LIDW
-40
o
C to 85
o
C
20 pin plastic SO
5V devices
3.3V devices
Wolfson Microelectronics
3
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
SYMBOL TEST CONDITIONS
MIN
TYP MAX
UNIT
Digital Inputs
High level output voltage
V
OH
V
CC
= 4.75 V, I
OH
= -360 mA
2.4
V
V
CC
= 4.75 V, I
OH
= -10 mA
4.5
V
Low level output voltage
V
OL
V
CC
= 5.25 V, I
OH
= 1.6 mA
0.4
V
High level input current
I
IH
V
IH
= 5 V
0.005
1
A
Low level input current
I
IL
V
IL
= 0 V
-0.005
-1
A
High level output (source)
I
OH
V
OH
= 0 V
-6.5
-24
mA
current
Low level output (sink) current
I
OL
V
OL
= V
CC
8
26
mA
High impedance-state
I
OZ
V
O
= 5 V
0.01
3
A
output current (DO)
V
O
= 0 V
-0.01
-3
A
Input capacitance
C
i
5
pF
Output capacitance
C
o
5
pF
Converter and Multiplexer
Total unadjusted error
TUE
V
REF
= 5 V. (note 7)
1
LSB
Differential Linearity
(note 8)
8
Bits
Supply voltage variation error
V
s(error)
V
CC
= 4.75 V to 5.25 V
1/16
1/4
LSB
Common mode error
Differential mode
1/16
1/4
LSB
Common mode input voltage
V
ICR
(note 9)
GND-0.05
V
range
V
CC
+0.05
Standby input leakage
I
I(stdby)
On-channel VI = 5 V at ON ch.
1
A
current (note 10)
Off-channel VI = 0 V at OFF ch.
-1
A
On-channel VI = 0 V at ON ch.
-1
A
Off-channel VI = 5 V at OFF ch.
1
A
Conversion time
tconv
Excluding MUX addressing time
8
clock
periods
Reference Inputs
Input resistance to
R
i(REF)
1.3
2.4
5.9
k
reference ladder
Total device
Supply current
I
CC
0.6
1.25
mA
Timing Parameters
Setup time, CS low or
t
su
350
ns
data valid before clock
Hold time, data valid after
t
h
90
ns
clock
Propagation delay time,
MSB data first. C
L
= 100 pF
1500
ns
output data after clock
t
pd
LSB data first. C
L
= 100 pF
600
ns
Output disable time, DO
t
dis
C
L
= 10 pF, R
L
= 10 k
125
250
ns
after CS
CL = 100 pF, R
L
= 2 k
500
ns
Wolfson Microelectronics
4
WM0834, WM0838
Recommended Operating Conditions (3.3V)
SYMBOL MIN NOMINAL MAX UNIT
Supply voltage
V
CC
2.7
3.3
3.6
V
High level input voltage
V
IH
2
V
Low level input voltage
V
IL
0.8
V
Clock frequency (Vcc = 3.3V)
f
clock
10
600
KHz
Clock duty cycle (see Note 4)
D
clk
40
60
%
Pulse duration CS high
t
wH(CS)
220
ns
Operating free-air temperature
C suffix
T
A
0
70
o
C
I Suffix
T
A
-40
85
Wolfson Microelectronics
5
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
SYMBOL TEST CONDITIONS
MIN
TYP MAX
UNIT
Digital Inputs
High level output voltage
V
OH
V
CC
= 3.0 V, I
OH
= -360 mA
2.4
V
V
CC
= 3.0V, I
OH
= -10 mA
2.8
V
Low level output voltage
V
OL
V
CC
=3.0V, I
OH
= 1.6 mA
0.4
V
High level input current
I
IH
V
IH
= 3.6V
0.005
1
A
Low level input current
I
IL
V
IL
= 0 V
-0.005
-1
A
High level output (source)
I
OH
V
OH
= 0 V, T
A
= 25
o
C
6.5
15
mA
current
Low level output (sink) current
I
OL
V
OL
= V
CC
, T
A
= 25
o
C
8
16
mA
High impedance-state
I
OZ
V
O
= 3.3 V, T
A
= 25
o
C
0.01
3
A
output current (DO)
V
O
= 0 V, T
A
= 25
o
C
-0.01
-3
A
Input capacitance
C
i
5
pF
Output capacitance
C
o
5
pF
Converter and Multiplexer
Total unadjusted error
TUE
V
REF
= 3.3 V. (note 7)
1
LSB
Differential Linearity
(note 8)
8
Bits
Supply voltage variation error
V
s(error)
V
CC
= 3.0 V to 3.6 V
1/16
1/4
LSB
Common mode error
Differential mode
1/16
1/4
LSB
Common mode input voltage
V
ICR
(note 9)
GND-0.05
V
range
V
CC
+0.05
Standby input leakage
I
I(stdby)
On-channel VI =3.3 V at ON ch.
1
A
current (note 10)
Off-channel VI = 0 V at OFF ch.
-1
A
On-channel VI = 0 V at ON ch.
-1
A
Off-channel VI =3.3V at OFF ch
1
A
Conversion time
tconv
Excluding MUX addressing time
8
clock
periods
Reference Inputs
Input resistance to
R
i(REF)
1.3
2.4
5.9
k
reference ladder
Total device
Supply current
I
CC
0.2
0.75
mA
Timing Parameters
Setup time, CS low or
t
su
350
ns
data valid before clock
Hold time, data valid after
t
h
90
ns
clock
Propagation delay time,
MSB data first. C
L
= 100 pF
500
ns
output data after clock
t
pd
LSB data first. C
L
= 100 pF
200
ns
Output disable time, DO
t
dis
C
L
= 10 pF, R
L
= 10 k
80
ns
after CS
CL = 100 pF, R
L
= 2 k
250
ns
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