TALER ADC180M, ADC180CA, ADC180C Datasheet

APPLICATIONS

• INERTIAL GUIDANCE

• TEST EQUIPMENT

• DATA ACQUISITION

• SCIENTIFIC INSTRUMENTS

• MEDICAL INSTRUMENTS

• WEIGHT SCALES

FEATURES

• 26 BIT RESOLUTION

• UP TO 2.5kHz CONVERSION RATES

• AUTO ZERO FUNCTION

• ±10.48 V INPUT RANGE

• 0.5ppm/°C MAX. SCALE FACTOR ERROR

AND 2 ppm MAX. LINEARITY ERROR
(-55°C to +125°C).

• 8 BIT PARALLEL DATA BUS

• INTERNAL CRYSTAL CLOCK and

PRECISION REFERENCE

• LOW POWER CONSUMPTION: 0.4 WATTS

DESCRIPTION

The ADC180 is a 26 bit, charge balanced A/D
converter. Continuous sampling of 20 MHz and
conversion rates of up to 2.5 kHz make the converter
ideal for low frequency signal measurement. The
integration time is user selectable through an
external capacitor.

The ADC180 will continuously collect and average
integrations until the user requests data. Converter
resolution is dependent on the number of integration
cycles completed before the data is requested.
Converter resolution ranges from 13 - 26 bits.

In order to retain accuracy, internal calculations are
made at a 32 bit level. The output of the result is
also made at the 32 bit level. This makes it possible
to use a relatively high conversion rate and average
the data external to the converter without loss of
accuracy due to computation roundoff errors. For
inertial guidance systems, velocity information can
be obtained at a high rate without loss of position
accuracy.

The use of hybrid technology allows for separation
of sensitive analog circuitry from digital circuit
noise. This produces far superior accuracy over
monolithic A/D convertors.

The converter uses a proprietary, patented charge
balance modulator. It has an internal crystal clock,
microcontroller, precision reference, and patented
nonlinear temperature compensation network which
provides excellent electrical performance over
temperature.

The maximum scale factor drift is 0.5ppm/oC,
maximum offset drift of 0.1ppm/oC, and a maximum
nonlinearity over the mil. temp. range of 2 ppm.

The ADC180 is packaged in a 40 pin hermetic
TDIP and requires ±15V and +5V supplies. The
converter dissipates 450 mW and is available in
commercial and military grades.

ADC180DS REV H MAR 00

ADC180
Programmable
Integrating A/D Converter

THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • [phone]

ELECTRICAL SPECIFICATIONS

MODEL
PARAMETER

ACCURACY

TEMPERATURE STABILITY

TIME STABILITY

ERROR ALL SOURCES

CONVERSION TIME
WARM-UP TIME

TEMPERATURE RANGE

DIGITAL OUTPUTS

DIGITAL INPUTS

POWER SUPPLY CURRENTS

POWER SUPPLY VOLTAGES

ANALOG INPUT CHARACTERISTICS

POWER SUPPLY REJECTION

Resolution
Input Equivalent Noise
Offset without Auto Zero
Offset with Auto Zero
Scale Factor Error
Noise (.1-10Hz) @ 10V
Nonlinearity
Normal Mode Rejection
Common Mode Rejection

Offset
Full Scale

Offset
Full Scale

MIN MAXTYP MIN MAXTYP MIN MAXTYP

ADC180C

ADC180CA ADC180M

bits
µV
ppm FS
ppm FS
ppm FS
µVpp
ppm FS
dB
dB

.25

6
1

*

*
*

*

*
*

*
*
*

*

60
80

*
*

*
*

0.2 0.1

*

1.0 0.5

*

ppm/oC
ppm/oC

0.1
2

ppm/24 hrs.

ppm/month

.0005, 2 .0003, 2 %, +/- counts

24 hrs, +/- 1 Deg. C Amb.

90 days, +/- 5 Deg. C Amb.

1 year, +/- 5 Deg. C Amb.

.0010, 2 .0008, 2

*

.0015, 2

.0013, 2

%, +/- counts
%, +/- counts

*
*

ms

*

5

*
* *

minutes

+Vcc, -Vee
5 VDC

80
80

* * dB
* * dB

Low

High

Low

High

-25

85 *

*

-55

125

V
V

V
V

0.8

*

*

4.0

* *

4.0

* *

0.8

* *

+Vcc

23

* * mA

-Vee

24

* *

mA

+Vdd

42

* *

mA

+Vcc

-Vee
+Vdd

+14.5 +15 +15.5

*
*
*

*
*
*

*
*
*

*
*
*

*
*
*

*
*
*

V

-14.5

-15 -15.5 V

+4.5

+5

+5.5

V

Input Range -10.485760

+10.485755

3

*

*

*

*

*

*

*

*

V

Bias Current 1.2

* *

nA
Input Impedance
Max. Input Voltage

200

* *

GO

2

0.5
50

*

* Same as ADC180C
Notes: 1) 60 Cycle 2) ( Max-Min Value) - Noise(0.1-10Hz)

ADC180

(Vcc = +15V, Vee = -15V, Vdd= + 5V, TA = +25oC)

*
*

*
*

4
1

100

2

(1)

o

C

(2)

26

*

*

32000.250

*

*

13

*

*

ADC180DS REV H MAR 00

V

-Vee +Vcc

THEORY OF OPERATION

The ADC180 uses a differential input to improve
accuracy. To measure single source voltages,

V

low

should be connected to the ground point of the
source voltage to be measured. In figure 1, the
switch is shown in the normal operating mode
connecting V

hi

and V

low

to the differential input of
the transadmittance amplifier. For an autozero
cycle, V

hi

is disconnected and the input to the
amplifier is shorted.
The charge balance modulator (figure 2) uses a
proprietary patented architecture to achieve the
high accuracy of the ADC180 without any error
correction method other than autozero. This
enables the converter to sample the output of the
transadmittance amplifier continuously at a
sampling rate of 20 MHz. This is important for
applications like inertial guidance systems where

Auto Zero Switch

Charge Balance

Modulator

Microprocessor

Output

Buffer

Crystal

Clock

Transadmittance

Amplifier

V

hi

V

low

Auto
Zero

Data

Request

Status

Lines

Output Enable

Data

Output

ï

ï

13

.
.
.

20

21

29

22

23

24

34 35

39

40

FIGURE 1. BLOCK DIAGRAM

Bidirectional

Curent
Source

∫

Direction

Switch

Bilevel

Comparator

Figure 2. Patented Charge Balance Modulator

The conversion result between two consecutive
data request inputs at times t1and t2is
mathematically represented by the equation

Data

Output

I

IN

ADC180DS REV H MAR 00

Duty Cycle

Test Point

3

20MHz clock output

26

The converter provides two 32 bit data words with
the first word containing t2-t1and the second word
containing

∫

⋅

−

=

2

1

12

1

t

t

inpiav

dtV

tt

V

dtV

t

t

inp

⋅

∫

2

1

dtV

t

t

inp

⋅

∫

2

1

must be measured without any loss of time
increments. The output of the charge balance
modulator is in the form of a pulse width
modulation signal. The internal microprocessor
provides all control functions and digital signal
processing.

The converter also has an internal crystal clock to
avoid phase jitter errors and a tristate output
buffer for easy interface with bus based systems.
For the data output timing see figures 5 and 6.