Datasheet WM0832LID, WM0832LCP, WM0832LCD, WM0832IP, WM0832ID Datasheet (Wolfson)

GND

CH0

CH1

DI

CLK

CS

DO

Vcc

V

REF

Start Conv

Mux Select

Input Latch

Internal CS

Control

Logic

Output Shift

Register

Comparator

WM0832

DAC

&

SAR

Logic

Input
MUX

G

LK

S

c

WM0831, WM0832

8-Bit ADCs with Serial Interface and

Differential or Dual Inputs

Production Data

Sept 1996 Rev 2.1

Description

WM0831 and WM0832 are 8-bit analogue to digital
converters (ADC) with serial I/O interfaces, providing a
choice of input configurations in 8-pin SO or DIP packages.
WM0831 has a differential input, also configurable as a
single ended input. A-D conversion results are serially
output on Data Out (DO) under the control of clock and chip
select inputs. The device has a separate voltage reference
input.
WM0832's two input multiplexer is configurable via the Data
In (DI) serial input, as two single ended inputs or a single
differential input. The voltage reference operates
ratiometrically and is internally connected to the VCC pin.
Conversion is initiated by bringing and holding chip select
low while providing a clock input. With WM0831's fixed
input configuration, the conversion result is output at DO on
the clock's falling edges in MSB to LSB order.
With WM0832's configurable input multiplexer, data is input
to DI on the rising edges of the clock to setup the Mux and
initiate conversion. Conversion results appear serially at
DO on the falling edges of the clock, first in MSB to LSB
order, and then repeated in LSB to MSB order.
WM0831/2 operate on 5V or 3.3V supply voltages and are
available in small outline and DIP packages for commercial

o

C) and industrial (-40 to 85oC) temperature ranges.

(0 to 70

Block Diagrams

WM0831

Features

• Functionally Equivalent to National Semiconduc­tor ADC0831 and ADC0832

• WM0831: Differential or single ended input

• WM0832: Two single ended inputs or a single
differential input

• Ratiometric reference input (fixed for WM0832)

• Serial I/O interface

• Input range 0 to Vcc with Vcc Reference

• 8 pin package, SO or DIP

• 5V and 3.3V variants

• Total Unadjusted Error: ± 1 LSB

• 8-bit resolution

µµ

• 32

µs conversion time at fclock = 250 kHz

µµ

Applications

• Embedding with remote sensors

• Equipment health monitoring

• Automotive

• Industrial control

WM0832

V

REF

Comparator

IN+

IN-

ND

Production Data data sheets contain final
specifications current on publication date. Supply
of products conforms to Wolfson Microelectronics
standard terms and conditions.

Differential

Input

WM0831

DAC

&

SAR

Logic

Output

Latch

Logic

Control

Wolfson Microelectronics

Lutton Court, Bernard Terrace, Edinburgh EH8 9NX, UK

Tel: [phone] Fax: [phone]

www: http://www.wolfson.co.uk

Vc

C

C

DO

© 1996 Wolfson Microelectronics

email: [email protected]

WM0831, WM0832

Top View

8 pin P (DIP) and D (SO) packages

WM0831 WM0832

Ordering InformationPin Configuration

5V devices
DEVICE TEMP. RANGE PACKAGE

WM0831CP 0oC to 70oC 8 pin plastic DIP
WM0831CD 0oC to 70oC 8 pin plastic SO
WM0831IP -40oC to 85oC 8 pin plastic DIP
WM0831ID -40oC to 85oC 8 pin plastic SO
WM0832CP 0oC to 70oC 8 pin plastic DIP
WM0832CD 0oC to 70oC 8 pin plastic SO
WM0832IP -40oC to 85oC 8 pin plastic DIP

o

WM0832ID -40

3.3V devices
DEVICE TEMP . RANGE PACKAGE

WM0831LCP 0oC to 70oC 8 pin plastic DIP
WM0831LCD 0oC to 70oC 8 pin plastic SO
WM0831LIP -40oC to 85oC 8 pin plastic DIP
WM0831LID -40oC to 85oC 8 pin plastic SO
WM0832LCP 0oC to 70oC 8 pin plastic DIP
WM0832LCD 0oC to 70oC 8 pin plastic SO
WM0832LIP -40oC to 85oC 8 pin plastic DIP

WM0832LID -40

C to 85oC 8 pin plastic SO

o

C to 85oC 8 pin plastic SO

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 . . . . T

WM083_C_ (C suffix) . . . . . . . . . 0oC to +70oC

WM083_I_ (I suffix) . . . . . . . . . . -40

Storage Temperature . . . . . . . . - 65

Soldering Information:
Lead Temperature 1.6 mm (1/16) from case

for 10 seconds: D or P package . . . . . . . 260

MIN to TMAX

o

C to +85oC

o

C to +150oC

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 VIH 2V
Low level input voltage VIL 0.8 V
Clock frequency fclock 10 600 KHz
Clock duty cycle (see Note 4) Dclk 40 60 %
Pulse duration CS high t wH(CS) 220 ns
Operating free-air temperature C suffix TA 070

o

C

I Suffix T A -40 85

Wolfson Microelectronics

2

WM0831, WM0832

Electrical Characteristics (5V)

Vcc = 5V , VREF = 5V,fCLK = 250KHz, TA = TMIN to TMAX, tr = tf = 20 ns, unless otherwise stated.

PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT

Digital Inputs

High level output voltage V

Low level output voltage VOL VCC = 5.25 V, IOH = 1.6 mA 0.4 V
High level input current IIH VIH = 5 V 0.005 1 µA
Low level input current IIL VIL = 0 V -0.005 -1 µA
High level output (source) IOH VOH = 0 V -6.5 -24 mA
current
Low level output (sink) current IOL VOL = VCC 826 mA
High impedance-state I OZ VO = 5 V 0.01 3 µA
output current (DO) VO = 0 V -0.01 -3 µA
Input capacitance CI 5pF
Output capacitance Co 5pF

Converter and Multiplexer

T otal unadjusted error TUE VREF = 5 V. (note 7) ±1 LSB
Differential Linearity (note 8) 8 Bits
Supply voltage variation error Vs(error) VCC = 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 VICR (note 9) GND-0.05 V
range VCC+0.05
Standby input leakage II(stdby) On-channel VI = 5 V at ON ch. 1 µA
current (note 10) Off-channel VI = 0 V at OFF ch. -1 µA

Conversion time tconv Excluding MUX addressing time 8 clock

Reference Inputs

Input resistance to Ri(REF) Can only be tested for WM0831 1.3 2.4 5.9 kΩ
reference ladder

Total device

Supply current WM0831 ICC 0.6 1.25 mA
Supply current WM0832 ICC ( note 11) 2.5 4.7 mA

Timing Parameters

Setup time, CS low or tsu 350 n s
WM0832 data valid before
clock
Hold time, WM0832 data th 90 ns
valid after clock
Propagation delay time, MSB data first. CL = 100 pF 1500 ns
output data after clock
Output disable time, DO tdis CL = 10 pF, RL = 10 kΩ 125 250 ns
after CS

OH VCC = 4.75 V, IOH = -360 µA2.4 V

VCC = 4.75 V, I OH = -10 µA4.5 V

On-channel VI = 0 V at ON ch. -1 µA
Off-channel VI = 5 V at OFF ch. 1 µA

periods

tpd LSB data first. CL = 100 pF 600 ns

CL = 100 pF, RL = 2 kΩ 500 ns

Wolfson Microelectronics

3

WM0831, WM0832

Recommended Operating Conditions (3.3V)

SYMBOL MIN NOMINAL MAX UNIT

Supply voltage VCC 2.7 3.3 3.6 V
High level input voltage VIH 2V
Low level input voltage VIL 0.8 V
Clock frequency (Vcc = 3.3V) fclock 10 600 KHz
Clock duty cycle (see Note 4) Dclk 40 60 %
Pulse duration CS high twH(CS) 220 n s
Operating free-air temperature C suffix TA 070

I Suffix T A -40 85

o

C

Wolfson Microelectronics

4

WM0831, WM0832

Electrical Characteristics (3.3V)

Vcc = 3.3V, fCLK = 250KHz, T A = TMIN to TMAX, tr = tf = 20 ns, unless otherwise stated.

PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT

Digital Inputs

High level output voltage V

Low level output voltage VOL VCC = 3V, IOH = 1.6 mA 0.4 V
High level input current IIH VIH = 3.6 V 0.005 1 µA
Low level input current IIL VIL = 0 V -0.005 -1 µA
High level output (source) IOH VOH = 0 V, TA = 25oC6.515 mA
current
Low level output (sink) current IOL VOL = 0V, TA = 25oC816 mA
High impedance-state I OZ VO = 3.3V, TA = 25oC 0.01 3 µA
output current (DO) VO = 0 V, TA = 25oC -0.01 -3 µA
Input capacitance CI 5pF
Output capacitance Co 5pF

Converter and Multiplexer

T otal unadjusted error TUE VREF = 3.3 V. (note 7) ±1 LSB
Differential Linearity (note 8) 8 Bits
Supply voltage variation error Vs(error) VCC = 3 V to 3.6 V ±1/16 ±1/4 LSB
Common mode error Differential mode ±1/16 ±1/4 LSB
Common mode input voltage VICR (note 9) GND-0.05 V
range VCC+0.05
Standby input leakage II(stdby) On-channel VI =3.3V at ON ch. 1 µA
current (note 10) Off-channel VI =0 V at OFF ch. -1 µA

Conversion time tconv Excluding MUX addressing time 8 clock

Reference Inputs

Input resistance to Ri(REF) Can only be tested for WM0831 1.3 2.4 5.9 kΩ
reference ladder

Total device

Supply current WM0831 ICC 0.2 0.75 mA
Supply current WM0832 ICC ( note 11) 1.5 2.5 mA

Timing Parameters

Setup time, CS low or tsu 350 n s
WM0832 data valid before
clock
Hold time, WM0832 data th 90 ns
valid after clock
Propagation delay time, MSB data first. CL = 100 pF 200 500 ns
output data after clock
Output disable time, DO tdis CL = 10 pF, RL = 10 kΩ 80 125 ns
after CS

OH VCC = 3V, IOH = -360 µA 2.4 V

VCC = 3 V, IOH = -10 µA 2.8 V

On-channel VI =0 V at ON ch. -1 µA
Off-channel VI =3.3V at OFF ch. 1 µA

periods

tpd LSB data first. CL = 100 pF 80 200 ns

CL = 100 pF, RL = 2 kΩ 250 ns

Wolfson Microelectronics

5

WM0831, WM0832

Electrical Characteristics (continued)

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. De­vice 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

power supply rails (GND > V
of current at that pin should be limited to 5 mA or less.

at any pin exceeds the

IN

> VCC) the absolute value

IN

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

devices and V

= 3.3V, TA = 25oC.

CC

= 5 V, TA = 25oC for 5V

CC

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
linearity error, zero code error and full scale error over
the output code range.

8. A Differential linearity of "n" bits ensures a code width
exists to "n" bits. Hence a Differential Linearity of 8
bits for an 8 bit ADC guarantees no missing codes.

9. For V

(-) greater than or equal to VIN(+) the digital out-

IN

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
analogue input voltage does not exceed the supply volt-

and GND. If an

CC

age by more than 50 mV, the output code will be cor­rect. T o use an absolute input voltage range of 0 to V
a minimum VCC - 0.05 V is required for all variations of
temperature. Care should be exercised when testing at

levels with a maximum analogue voltage as

low V

CC

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.

11. For WM0832 the reference current is included in the
supply current as V

is internally connected to VCC.

REF

CC

Wolfson Microelectronics

6

Test Circuits and Waveforms

Output Disable Time Voltage Waveforms and Test Circuits

WM0831, WM0832

Standby Leakage Current Test Circuit

Detailed Timing Diagrams

WM0832 Data Input Timing

Wolfson Microelectronics

Data Output Timing

7

WM0831, WM0832

Performance Data (typical)

1

0.75

0.5

0.25

0

Error (lsbs)

-0.25

-0.5

-0.75

-1
0 32 64 96 128 160 192 224 256

Code

WM0832: Total Unadjusted Error

1

0.75

WM0831: Total Unadjusted Error

0.5

0.25

0

Error (lsbs)

-0.25

-0.5

-0.75

-1
0 32 64 96 128 160 192 224 256

Code

T est conditions: V

CC = 5V. VREF = 5V , Temp = 25

o

C, FCLK = 250KHz

Wolfson Microelectronics

8

Functional Timing Diagrams

WM0831, WM0832

WM0831 Timing

WM0832 Timing

Wolfson Microelectronics

9

WM0831, WM0832

Pin Descriptions

WM0831
Pin Name Type Function

1 CS Digital Chip Select

(active low)

2 IN + Analogue input Positive differential

input

3 I N - Analogue input Negative differential

input

4 GND Supply Analogue and digital

ground

5VREF Analogue input Voltage reference

input
6 DO Digital input Data Output
7 CLK Digital input Clock input
8VCC Supply Positive supply

voltage

Multiplexer / Package Options
Device Number of Analogue Channels Number of
No Single Ended Differential Package Pins

WM0831 1 1 8
WM0832 2 1 8

WM0832
Pin Name Type Function

1 CS Digital Chip Select

2 CH0 Analogue input Channel 0 input to

3 CH1 Analogue input Channel 1 input to

4 GND Supply Analogue and

5 DI Digital input Data input
6 DO Digital input Data Output
7 CLK Digital input Clock input
8VCC/VREF Supply/Analogue I/P Positive supply

Functional Description

Input and Multiplexer Operation and Addressing

WM0831 has two inputs IN+ and IN- configured for
differential operation, single ended operation is achieved
by grounding IN- to an analogue common or GND.
WM0832 uses an input multiplexer scheme with two input
channels, configurable for single-ended or differential
operation. The single ended input uses the GND pin as its
analogue ground reference.

WM0831/2 uses a successive approximation routine to
perform A/D conversion and employs a sample data
comparator structure which always performs conversion
on a differential voltage. Conversion takes place on the
voltage difference between assigned “+” and “-” inputs and
the converter expects the “+” input to be the most positive,
if the “+” input is more negative than “-” then the converter
gives an all zeros output. Assignment of WM0832 inputs
is made for a single-ended signal between an “+” input
and (analogue) ground (GND), or for a differential input
between CH0 and CH1 inputs of either polarity.

For WM0832 prior to the start of every conversion the input
configuration is assigned during the MUX addressing
sequence by serially shifting data into the Data Input (DI) on
the second and third rising edges of the clock input. The
MUX address selects which analogue inputs are enabled,
either single-ended or differential. For differential inputs the
polarity of the inputs are also assigned. The MUX
addressing table gives full details of input assignments.
Because WM0831 has only one differential input of fixed
polarity it does not require addressing.

WM0832 MUX Addressing
MUX Address Channel Number
SGL/DIF ODD/EVEN 0 1
Differential MUX Mode

00+-
01-+

Single Ended MUX Mode

10+
11 +

(active low)

multiplexer (MUX)

multiplexer (MUX)

digital ground

voltage and
voltage(ratiometric)
reference input

10

Wolfson Microelectronics

Functional Description (continued)

WM0831, WM0832

Initiating Conversion and the Digital Interface

WM0831 and WM0832 are controlled from a processor
via a Chip Select (CS) input and a serial interface
comprising Data Out (DO) and additionally for WM0832 a
Data In (DI) input.

For WM0831 conversion is initiated by pulling chip select
low and inputting a clock signal. On the clock's first falling
edge after CS is brought low, DO output comes out of
high impedance mode. On the second and subsequent
clock falling edges, to a total of nine, the conversion
result is output on DO in MSB to LSB order. WM0831 only
provides output data in MSB first order.

For WM0832 conversion is also initiated by pulling the chip
select (CS) line low and inputting a clock signal but MUX
addressing information has also to be input on DI. The
start bit and the MUX assignment bits on DI are clocked
in on the first three rising edges of the clock input which
may be generated by the processor or run continuously.
WM0832 uses two MUX assignment bits.

When the logic “1” start bit is clocked into the start
conversion location of the multiplexer input register the
analogue MUX inputs are selected. After 1/2 a clock
period delay to allow for the selected MUX output to settle
the conversion commences using the successive
approximation technique.

When conversion begins the A/D conversion result from
the output of the SARS comparator appears at the DO
output on each falling edge of the clock (see Functional
Timing Diagrams).

With the successive approximation A/D conversion
routine the analogue input is compared with the output of
a digital to analogue converter (DAC) for each bit by the
SARS comparator and a decision made on whether the
analogue input is higher or lower than the DAC output.
Successive bits, MSB to LSB, are input to the DAC and
remain in its input if the analogue comparison decides
the analogue input is higher than the DAC output, if not
the bit is removed from the DAC input. There is no sample
and hold. The input needs to be stable during T conv period
(see Functional Timing Diagrams).

For WM0832 the 8 bits of the conversion are stored in an
output shift register, after a conversion has completed and
MSB first data has been output WM0832 automatically
shifts out LSB first data on the DO output.

CS must be held low through an entire conversion, all
internal registers are cleared when CS is high. To initiate
another conversion CS must make a high to low transition
and for WM0832 MUX address assignments input to DI.

For WM0832 the DI input and DO output can be tied
together and controlled via a bidirectional processor I/O
bit line.

Reference Input

The analogue input voltage range, Vmax to Vmin for
differential inputs is defined by the voltage applied to the
reference input with respect to GND. WM0832 is fixed in a
ratiometric mode with VREF internally tied to Vcc, WM0832
has a separate VREF pin and can be used in either
ratiometric applications or those requiring absolute
accuracy.

A ratiometric reference input, typically the Vcc, is the same
supply used to power analogue input circuitry and
sensors. In such systems under a given input condition
the same code will be output with variations in supply
voltage because the same ratio change occurs in both the
analogue and reference input to the A/D. When used in
applications requiring absolute accuracy a suitable time
and temperature stable voltage reference source should
be used.

The voltage source used to drive the reference input should
be capable of driving the 2.4 kΩ typical of the SAR
resistor ladder. The maximum input voltage to the
reference input is the Vcc supply voltage. The minimum
for WM0832 can be at least as low as 1 V to allow for
direct conversion of sensor outputs with output voltage
ranges less than 5 V.

The output from the SARS comparator forms the
resulting input to the DAC and the A/D conversion output
on DO, and is read by the processor as conversion takes
place in MSB to LSB order. After 8 clock periods the
conversion is complete.

Wolfson Microelectronics

11

WM0831, WM0832

Functional Description (continued)

Analogue Inputs.

While sampling the analogue inputs short spikes of
current enter a “+” input and flow out of the corresponding
“-” input at the clock edges during conversion. This
current does not cause errors as it decays rapidly and the
internal comparator is strobed at the end of a clock
period. Care should be exercised if bypass capacitors are
used at the inputs, as an apparent offset error can be
caused by the capacitor averaging the input current and
developing a voltage across the source resistance.
Bypass capacitors should not be used with a source
resistance greater than 1kΩ.

In considering error sources, input leakage current will also
cause a voltage drop across the source resistance and
hence high impedance sources should be buffered.

In differential mode there is a 1/2 clock period interval be­tween sampling the “+” and the “-” inputs. If there is a change
in common mode voltage during this interval an error could
notionally result.

For a sinusoidal common mode signal the error is given
by : VERROR = VPEAK (2πfCM) (1/(2fCLK))

Where VPEAK = Peak common mode voltage
f
f

CM = Common mode signal frequency

CLK = Clock frequency.

12

Wolfson Microelectronics

Package Descriptions

Plastic Small-Outline Package

D - 8 pins shown

WM0831, WM0832

4.00

3.80

6.20

5.80

1.75

1.35

0.25

0.10

A

58

14

Pin spacing

1.27 B.S.C.

Dimension 'A' Variations

NMinMax

8 4.80 5.00
14 8.55 8.75
16 9.80 10.00

0.51

0.33

0.50

0.25

O

x 45 NOM

1.27

0.40

0.25

0.19

OO

0 to 8

Notes:

A. Dimensions in millimeters.
B. Complies with Jedec standard MS-012.
C. This drawing is subject to change without notice.
D. Body dimensions do not include mold flash or protrusion.
E. Dimension A, mould flash or protrusion shall not exceed 0.15mm. Body width, interlead flash or protrusions shall

not exceed 0.25mm.

Rev. 1 November 96

Wolfson Microelectronics

13

WM0831, WM0832

Package Descriptions

Dual-In-Line Package

N or P

N

0.005
Min.

1

0.070 Max.

Pin spacing

0.100 B.S.C.

A

0.045

0.030

0.022

0.014

O

105

O

90

0.014

0.008

Dimension 'A' Variations

0.325

0.290

0.280

0.240

Seating
plane

0.210 Max.

0.150

0.115

0.015
Min.

NMinMax

8 0.355 0.400
14 0.735 0. 775
16 0.735 0. 775
20 0.940 0. 975

Notes:

A. Dimensions are in inches
B. Falls within JEDEC MS-001( 20 pin package is shorter than MS-001)
C. N is the maximum number of terminals
D. All end pins are partial width pins as shown, except the 14 pin package which is full width.

N/2

14

Rev. 1 November 96

Wolfson Microelectronics