USTI datasheet(2/3 Pages) TAB

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selected by using four selection external pins M0-M2

and the relative error by using four selection pins N0-

N2 (RS232 master communication mode). The mode

and accuracy can be also selected by using any of

three possible interfaces (slave communication mode).

A communication interface type (RS232, SPI or I

2C)

can be automatically selected according to the circuit

connection.

MEASURING MODES

 Frequency, fx 0.05 Hz – 9 MHz directly and up to

144 MHz with prescaling

 Period, TX 110 ns – 20 s

 Phase shift, X 0 - 360º at fxmax = 625 kHz

at 50 % duty-cycle

 Time interval between start – and stop-pulse, X

1.5 µs – 250 s

 Duty-cycle, DC 0 – 1 at fxmax ≤ 625 kHz

 Duty-off factor, Q1 10

-8 – 8·106 at f

xmax ≤ 625 kHz

 Frequency difference, fX2 – fX2 with sign recognition,

0 – 9 MHz

 Period difference, TX1 – TX2 with sign recognition,

0 – 20 s

 Frequency ratio, fX1/fX2 5.5·10

-9 – 1.8·108

 Period ratio, TX1/TX2 4.0·10

-9 – 2·108

 Rotation speed, nX = (fX·60)/Z, where Z

is the number of encoder teeth

 Pulse width, tP 1.5 µs – 250 s

 Space interval, tS 1.5 µs – 250 s

 Pulse number (events) counting, NX 0 – 4·10

 Frequency deviation absolute DA1, 0-9 MHz

 Frequency deviation relative DR1, 0-100 %

 Resistance, Rx 10  to 10 M with average relative

error

0.47 % and 0.01 % error at splitting of the

range into sub ranges

 Capacitance, Cx 50 pF to 100 F with average

relative error

0.036 % and 0.7 % the worst case

relative error

 Resistive bridges, Bx must not include any internal

components other than 4 arms forming a bridge

NOTE: The USTI can also work with any voltage and

current output sensors. It this case, any voltage–to-

frequency converter (VFC) can be used. The accuracy

of such system will be determined by sensor accuracy

as well as by VFC accuracy.

ACCURACY

The USTI has programmable relative error from 1 to

0.0005 % in all specified range of frequencies for

frequency and period measurements. This error is

constant and does not depend on the measuring

frequencies in all frequency ranges. The USTI has

non-redundant conversion time. The higher conversion

accuracy needs longer conversion time. However, it is

non-redundant

for

any

selected

accuracy

and

frequency. For time interval, phase shift, pulse width

and space measurements the relative error is

determined mainly by measurnd and can be calculated

according to the following equation:

100









where tx is the appropriate measuring value of tp, ts or

x depending on the mode.

COMMUNICATION MODES

The USTI can work as an independent measuring unit

(master

mode),

controlled

any

external

microcontroller (or embedded into a sensor), DAQ

board or PC (slave mode). In the master mode, the

conversion accuracy and measurement mode should

be selected by external switches. In this mode the

USTI works only through the RS232 interface in a

unidirectional mode. In the slave mode (with an

external microcontroller), all measuring modes and

programmed accuracy can be set up by a data bus or

through

communication

I/O

ports

master

microcontroller. This allows us use the USTI as a

simple peripheral circuit for a microcontroller. A

bidirectional data exchange is possible with any of

three interfaces RS232, SPI or I

2C. The USTI works as

a standard element in different systems with I

2C bus

architecture, or can be controlled through the RS232

or SPI interfaces. The choice of interface can be

performed automatically depend on the circuit

connections.

The selection of communication interface is performed

automatically based on the state of IS1 and IS2 inputs

at the power switch on:

IS1

IS2

Communication Interface

SPI slave

I2C slave

RS232 master

RS232 slave

CHARACTERISTICS

 Single power supply, V: 4.5 – 5.5

 External reference frequency, MHz: 20

 Internal reference frequency, kHz: 625

 Conversion time, s: 0.00016 to 0.32

 Supply current (at 20 MHz, 4.5V, 25ºC), mA: < 9.5

 Operating temperature range -40ºC to +85ºC

 Storage temperature range -65°C to +150°C

PIN-OUT AND HOUSING

The USTI is available in a 28-lead (0.300"/7.62 mm

Wide) Plastic Dual Inline Package (PDIP); 32-lead 7 x

7 mm Body Size, 1.0 mm Body Thickness, 0.8 mm

Lead Pitch small Thin Profile Plastic Quad Flat

Package (TQFP); and 32-pad, 5 x 5 x 1.0 mm Body,

USTI Datasheet(PDF) 2 Page - TECHNOLOGY ASSISTANCE BCNA 2010, S. L.

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