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
µµµµµ
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
µ
A
Low level input current
I
IL
V
IL
= 0 V
-0.005
-1
µ
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
µ
A
output current (DO)
V
O
= 0 V
-0.01
-3
µ
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
µ
A
current (note 10)
Off-channel VI = 0 V at OFF ch.
-1
µ
A
On-channel VI = 0 V at ON ch.
-1
µ
A
Off-channel VI = 5 V at OFF ch.
1
µ
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
Ω
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
Ω
125
250
ns
after CS
CL = 100 pF, R
L
= 2 k
Ω
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
µ
A
Low level input current
I
IL
V
IL
= 0 V
-0.005
-1
µ
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
µ
A
output current (DO)
V
O
= 0 V, T
A
= 25
o
C
-0.01
-3
µ
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
µ
A
current (note 10)
Off-channel VI = 0 V at OFF ch.
-1
µ
A
On-channel VI = 0 V at ON ch.
-1
µ
A
Off-channel VI =3.3V at OFF ch
1
µ
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
Ω
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
Ω
80
ns
after CS
CL = 100 pF, R
L
= 2 k
Ω
250
ns
Wolfson Microelectronics
6
WM0834, WM0838
Notes:
1.
Absolute Maximum Ratings are stress ratings only.
Permanent damage to the device may be caused by
continuously operating at or beyond these limits. De-
vice functional operating range limits are given under
Recommended Operating Conditions. Guaranteed
performance specifications are given under Electrical
Characteristics at the test conditions specified.
2.
All voltage values, except differential voltages are with
respect to the ground.
3.
When the input voltage V
IN
at any pin exceeds the
power supply rails (GND > V
IN
> V
CC
) the absolute value
of current at that pin should be limited to 5 mA or less.
The 20 mA package input current limits the number of
pins that can exceed the power supply boundaries
with a 5 mA supply current to four.
4.
A clock duty cycle range of 40% to 60% ensures
correct operation at all clock frequencies. For a clock
with a duty cycle outside these limits, the minimum time
the clock is high or low must be at least 666 ns, with
the maximum time for clock high or low being 60 ms.
5.
All typical values are at V
CC
= 5 V, T
A
= 25
o
C for 5V
devices and V
CC
= 3.3 V, T
A
= 25
o
C for 3.3V devices.
Electrical Characteristics
(continued)
6.
All parameters are measured under open-loop
conditions with zero common mode input voltage
(unless otherwise stated).
7.
Total Unadjusted Error (TUE) is the sum of integral lin-
earity error, zero code error and full scale error over
the output code range.
8.
A Differential linearity of "n" bits ensures a code width
exist to "n" bits. Hence a Differential Linearity of 8 bits
for an 8 bit ADC guarantees no missing codes.
9.
For V
IN
(-) greater than or equal to V
IN
(+) the digital out-
put code will be 00 Hex. Connected to each analogue
input are two diodes which will forward conduct for a
diode drop outside the supply rails, V
CC
and GND. If an
analogue input voltage does not exceed the supply volt-
age by more than 50 mV, the output code will be cor-
rect. To use an absolute input voltage range of 0 to V
CC
a minimum V
CC
- 0.05 V is required for all variations of
temperature. Care should be exercised when testing at
low V
CC
levels with a maximum analogue voltage as
this can cause the input diode to conduct, especially at
high temperature, and cause errors for analogue inputs
near full scale.
10. Standby input leakage currents, are currents going in
or out of the on or off channels when the ADC is not
performing conversion and the clock input is in a high
or low steady-state condition.
Wolfson Microelectronics
7
WM0834, WM0838
Test Circuits and Waveforms
Output Disable Time Voltage Waveforms and Test Circuits
Standby Leakage Current Test Circuit
Detailed Timing Diagrams
Data Input Timing
Data Output Timing
V
cc
V
cc
V
cc
GND
GND
GND
t
su
t
su
t
h
t
h
50%
50%
50%
50%
50%
50%
50%
2V
2V
0.4V
0.4V
0.4V
CLK
CLK
CS
DI
(Data In)
t
pd
t
pd
t
su
V
cc
V
cc
V
cc
GND
GND
GND
(Data
Out)
DO
SE
Wolfson Microelectronics
8
WM0834, WM0838
Functional Timing Diagrams
WM0834 Timing
WM0838 Timing
Wolfson Microelectronics
9
WM0834, WM0838
WM0834
Pin
Name Type
Function
1
NC
No connection
2
CS
Digital
Chip Select
(active low)
3
CH0
Analogue input Channel 0 input
to multiplexer (MUX)
4
CH1
Analogue input Channel 1 input
to multiplexer (MUX)
5
CH2
Analogue input Channel 2 input
to multiplexer (MUX)
6
CH3
Analogue input Channel 3 input
to multiplexer (MUX)
7
DGND
Supply
Digital ground pin
8
AGND
Supply
Analogue ground pin
9
V
REF
Analogue input Voltage reference
input
10
DO
Digital output
Data output
11
SARS
Digital output
Successive
approximation
registar status line
12
CLK
Digital input
Clock input
13
DI
Digital input
Data input
14
V
CC
Supply
Positive supply
voltage
Pin Descriptions
WM0832
Pin
Name Type
Function
1
CH0
Analogue input
Channel 0 input
to multiplexer (MUX)
2
CH1
Analogue input
Channel 1 input to
multiplexer (MUX)
3
CH2
Analogue input
Channel 2 input to
multiplexer (MUX)
4
CH3
Analogue input
Channel 3 input to
multiplexer (MUX)
5
CH4
Analogue input
Channel 4 input to
multiplexer (MUX)
6
CH5
Analogue input
Channel 5 input to
multiplexer (MUX)
7
CH6
Analogue input
Channel 6 input to
multiplexer (MUX)
8
CH7
Analogue input
Channel 7 input to
multiplexer (MUX)
9
COM
Analogue input
Common input for
pseudo differential
mode
10
DGND
Supply
Digital ground pin
11
AGND
Supply
Analogue ground pin
12
VREF
Analogue input
Voltage reference
input
13
SE
Digital input
Shift enable control
line (active low)
14
DO
Digital output
Data Output
15
SARS
Digital output
Successive
approximation
register status line
output
16
CLK