VERSION CHANGES

NO.

ISSUE

APPROVED

All information contained in this Data Sheet is the property of

MAZeT. Nothing in this catalog may be reproduced or multiplied in
any way, neither electronically nor mechanically, unless the express
approval of MAZeTGmbH has been procured. Any company and
brand and product names quoted herein are typically subject to
trademark, patent or propietary protection right.

V1.4

Approvals

Date

MAZeT GmbH

Compiled:

2001-03-16

Checked:

2002-07-09

Status: Data sheet

MAZeT GmbH Sales office
G鰏chwitzer Stra遝 32
D-07745 Jena / Germany
Phone: +49/3641-2809-0
Fax: +49/3641-2809-12

Email: sales@MAZeT.de
URL: http://www.MAZeT.de

Released:

2002-07-09

DOC. NO: DB99085e

Sheet 1 of 22

Data Sheet

MSI 01

Sensor Interface IC

Contents

1. FUNCTION

1.1.

General

1.1.1. Features

1.1.2. Applications

1.1.3. MSI-EB1 Evaluation Board

1.2.

Analog Components

1.2.1. Power Supply

1.2.2. Signal Processing

1.2.3. Sensor Interfacing Connections

1.3.

Digital Components

1.3.1. Register Block

1.3.2. Serial Interface

1.3.3. Logic Control Block

1.3.4. Signal Declarations

2. ELECTRIC PARAMETERS

2.1.

Absolute Limit Values

2.2.

Operating Parameters

2.3.

AC/DC Features

3. DESCRIPTION OF MSI 01 PACKAGE

3.1.

Ordering Specifications

3.2. PQFP44 Package Dimensions

3.3.

Pin-Out Assignments

4. APPLICATION CIRCUIT

VERSION

NO.

ISSUE

APPROVED

V 1.4

All information published in this document reflect the state of the art at the moment of
publishing and are of temporary nature. MAZeT expressly reserve the right to make
engineering changes regarding devices and components described in this document.

DOC. NO:

DB99085E

Page 2 of 22

Data sheet MSI 01

1. Function

1.1. General

The MSI 01 is a highly integrated sensor interface
IC capable of processing the signals from up to
four differential-output sensors on its input side. It
is specifically designed for interfacing with bridge
sensors that deliver ratiometric output signals. An
input circuit which is configurable in terms of gain,
zero-point and resolution amplifies, filters and
converts the incoming analog signals into digital
ones. They are then made available at a digital
interface by a downstream evaluation module.

The MSI 01 offers two possibilities of temperature
compensation:
1) An on-chip integral temperature measurement

that can be used e.g. to compensate the
temperature behaviour of connected sensors
and that of the MSI 01.

2) An external temperature compensation that

measures the response of a bridge resistor to
temperature changes against a voltage divider
(see section. 1.2.3. Sensor Interfacing
Connections).

In addition to its integrated on-chip functionality,
the MSI 01 notably features a very high signal
resolution while maintaining signal stability and
consuming little current.
The MSI 01 is designed to evaluate differential
sensor signals of the type as delivered by e.g.
pressure sensors, hall sensors and sensors
working on the principle of a resistance measuring
bridge (strain measuring bridges, piezo or mag-
neto-resistive sensors). These sensors are

activated by the MSI 01. Per working cycle,
current is only supplied to the sensor bridge and
only for as long as measurement lasts. Power
supply of the bridge circuit can be in current mode
or voltage mode.

Equipped with an additional option for recording a
'0' input voltage (auto zero) or the voltage of an
internal or external calibration divider, the MSI 01
allows balancing to be performed at zero value or
full scale value. Since the preamplifier works
based on the chopper principle, very small signal
amplitudes can be evaluated. The chopper
transforms a given input signal into a frequency
range such that interferences in the transmission
channel will only be caused by the low level of
white noise portions. As a consequence, 1/f noise
portions prevailing in the low frequency and DC
ranges are strongly suppressed.
Because of its small dimensions (PQFP44) and
little power consumption (2 mA and 3 uA in stand-
by mode resp.), the MSI 01 can be directly
mounted at the sensor (e.g. in sensor heads), and
sensors which are connected via the MSI 01 can
be directly supplied with current and voltage.

Thanks to its integral temperature sensing ability,
the MSI 01 can preferentially be employed where
sensor characteristics have to be corrected for
matching to temperature conditions (e.g. Hall sen-
sors or strain measuring bridges), and further
where integrated signal conditioning solutions are
required.

VERSION

NO.

ISSUE

APPROVED

V 1.4

DOC. NO:

DB99085E

Page 3 of 22

Data sheet MSI 01

Evaluation-Board MSI-EB1

1.1.1. Features

�

Four input channels (multiplex)

�

Bridge current or voltage is supplied via the MSI 01 just for as long as the selected sensor

bridge takes to finish measurement

�

Low power design allows battery-operated mode

�

15-bit

resolution

�

Charge balancing ADC for excellent noise suppression

�

Unipolar and bipolar measurement

�

'Backrgound measurement' mode allows measurement without activation of 礐

�

Small temperature coefficient due to in-chip and external temperature measurement

�

Interrupt is generated on excession of limiting value

�

Data output via serial interface

�

Built-in pulse counter for use as gas flow meter (gas meter)

1.1.2. Applications

�

Battery-supported sensor electronics (pressure, temperature, strain gauge, etc.)

�

Data logger for measuring pressure and temperature in gas and water supply nets

�

Autonomous gas pressure monitoring devices

�

Weather

stations

�

Gas meters (gas quantity meters)

1.1.3. MSI-EB1 Evaluation Board

The evaluation board provides three plug-in bases for
sensor modules to allow individualized connection of those
sensors which the user needs to evaluate. The test
environment is completed by a Windows-based graphical
user screen for fast and easy access to the MCI's
functionality.
Features of this user screen include sample configurations
of the MSI 01, consecutive measurements with graphical
representation of results, access to all MSI 01
configurations (bits).
The graphical user screen ensures easy availability of the whole range of MSI 01 functions and
parameters.

VERSION

NO.

ISSUE

APPROVED

V 1.4

DOC. NO:

DB99085E

Page 4 of 22

Data sheet MSI 01

1.2. Analog

Components

1.2.1. Power

Supply

Figure 1 shows a separate MSI 01 power supply diagram.

Figure 1: MSI 01 power supply

For MSI 01 operation, a voltage of 6 V is supplied, preferentially from a battery via an on-chip in-phase

regulator (STAB). It outputs a stabilized voltage V

DDA

of about 3.3 V which also powers the bridge sensors.

Since the absolute voltage value is subject to relatively broad process tolerances (about

�

10%), the serial

interface is prepared to calibrate to approximately

�

3%. The regulator has a built-in reset function (PON)

to output a static reset signal (high-active), as soon as the operating voltage drops below the power-fail

threshold. On excession of this power-on threshold, the reset signal will switch off with a certain time de-

lay.

At the same time, the V

DDA

supply voltage is also used as reference voltage for the ADC, which ensures

ratiometric measurement of the bridge signals. A derivative of the V

DDA

supply voltage is the V

voltage

which is intended to power an external controller and further system components.

To reduce retro-interference effects from the controller's operating voltage, a resistor of about 5 ohms

isolates the V

voltage from V

DDA

(regulator output voltage).

With the MSI 01 in power-down mode, all analog circuitry parts, including also the bridge supply compo-

nents, are turned off. The in-phase regulator will continue to operate in a current saving stand-by mode

(diminished regulation dynamics) so as to preserve the data contents of all digital registers, keep the in-

terface in operating condition and maintain power supply of external components.

The reset circuit will also remain active. Because this leads to a change in the regulator's working point,

the regulator output voltage may in stand-by mode insignificantly differ from that in normal operating mode

(

<100mV).

STAB

Sensors

3,7V ... 6,6V

VDDA

3,3V�3%

VBPx

RIBx

VSSA

VSS

SGND=VDDA/2

VDD

10n

10�

3,3V�3%

to 礐ontroller

5 Ohm

VBAT

VBN

220n

VERSION

NO.

ISSUE

APPROVED

V 1.4

DOC. NO:

DB99085E

Page 5 of 22

Data sheet MSI 01

1.2.2. Signal

Processing

A block diagram of the MSI 01 is contained in Figure 2. A required external or internal signal is selected by
an input multiplexer (MUX) to be connected to the input of the measuring channel. Supported measuring
modes are:

�

Differential measurement IPx � INx

�

Differential measurement (IPx + INx)/2 � ICx (only for inputs 1 and 2)

�

Measurement of on-chip temperature sensor voltage

�

Measurement of battery voltage via internal voltage divider

�

Auto zero measurement (both inputs of measuring channel internally connected to AGND)

�

Measurement of different pick-offs of a symmetric internal calibration divider (ratiometric)

Figure 2: Block diagram of MSI 01

The measuring channel consists of a low-noise preamplifier (CVV) with four selectable gains, one filter
amplifier (FV) for signal band limitation and an AD converter (ADC) with four selectable zero-point levels
and four selectable resolutions. Configuration of the measuring channel (source, sensititivity, zero-point,
resolution) is performed with the help of an interface command before or on starting of measurement.

Battery voltage measurement is restricted to a V

DDA

range of +0.1 V to approximately 7.2 V, because ade-

quate measuring accuracy is not guaranteed with smaller voltages. Battery voltage measurement must be
calibrated as the supply voltage which serves for reference voltage is subject to relatively strong exem-
plary variations.

Result counter

Summator

Time counter

RTC-prescaler

MODE register

Impuls counter

Realtime counter

Parallel PORT

Configuration

RTC

INT

SDAT

SCLK

TEST

FCL

VBN

VBP3

VBP2

VBP1

VBP0

VBP

IN3

IP3

IC2

IN2

IP2

IC1

IN1

IP1

IN0

IP0

AGND

Test

scaler

Temp

sensor

Analogue

multiplexer

Preamplifier

antialiasing

Power-ON

Power-FAIL

RESET

A/D-Converter

Voltage

controller

Limit value register

Digital comparator

Bridge
supply

Clock generator

Control unit

Serial interface

协谢械泻褌褉芯薪薪褘泄 泻芯屑锌芯薪械薪褌: MSI

协谢械泻褌褉芯薪薪褘泄泻芯屑锌芯薪械薪褌: MSI