HI7190EVAL Intersil, HI7190EVAL Datasheet

HI7190EVAL

Manufacturer Part Number

HI7190EVAL

Description

EVALUATION PLATFORM HI7190

Manufacturer

Intersil

Datasheets

1.HI7190IBZ.pdf (25 pages)

2.HI7190EVAL.pdf (11 pages)

Specifications of HI7190EVAL

Number Of Adc's

Number Of Bits

Sampling Rate (per Second)

200k

Data Interface

Serial

Inputs Per Adc

1 Differential

Input Range

±2.5 V

Power (typ) @ Conditions

15mW @ 200kSPS

Voltage Supply Source

Analog and Digital, Dual ±

Operating Temperature

-40°C ~ 85°C

Utilized Ic / Part

HI7190

Lead Free Status / RoHS Status

Contains lead / RoHS non-compliant

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No. AN9505

Evaluation Kit Description

The HI7190 evaluation kit (evaluation board and evaluation

software) can be used to evaluate the performance of the

HI7190 24-bit sigma delta analog-to-digital converter (ADC).

The evaluation board includes a reference circuit, a crystal,

an oscillator, and digital circuitry used to interface to a per-

sonal computer running the evaluation software. The board

also provides a means for the user to supply an external ref-

erence and an external clock.

HI7190 Description

The HI7190 is a 24-bit sigma delta ADC intended for use in

applications such as industrial weight scales, process con-

trols, and process measurement systems. The block dia-

gram shows that the device consists of a programmable gain

instrumentation ampliﬁer (PGIA), a second order sigma delta

modulator, a digital ﬁlter, a clock generator, and digital con-

trol and interface circuitry.

The input signal applied to the V

into the PGIA where it is gained up by a factor of 1 to 8. The

resulting signal is then passed into the oversampling second

order sigma delta modulator for A/D conversion and noise

shaping. The output of the modulator is a serial bit stream of

“1”s and “0”s whose code density is a direct indication of the

value of the input to the modulator. This bit stream is then

input to the digital ﬁlter where it is band limited and deci-

mated down to a lower frequency. The digital ﬁlter is also

used (along with the PGIA) to implement gains up to 128.

The clock generator and digital control circuits direct the

internal conversion process while the serial interface unit

provides access to the device from the outside world. For a

detailed description of the operation of the converter, please

refer to the HI7190 data sheet.

Hardware Description

The HI7190 evaluation board provides the user with a very sim-

ple way of interfacing to and evaluating the Intersil HI7190

sigma delta ADC. The board features a reference voltage gen-

erator, a crystal oscillator, and digital line drivers and receivers

for interfacing to a PC running the evaluation software. The

board consists of 4 layers with separate analog and digital

ground planes for obtaining optimum noise performance.

Intersil Corporation 1995

March 1995

USING THE HI7190 EVALUATION KIT

INHI

and V

Authors: David Jarman and John Kornblum

INLO

pins comes

Layout and Power Supplies

The HI7190 evaluation board consists of 4 layers laid out to

optimize performance of the ADC. The ﬁgures at the end of

this document include the various layers of the board and

their layout, a list of the board components, and schematics.

Users should feel free to copy this layout for use in their

applications.

The power supplies are provided to the board via the edge

connector located at the top of the board. It is recommended

that twisted pair wires be used to connect the power sup-

plies to the connector and that analog and digital grounds be

tied together back at the power supplies. The separate sup-

plies are necessary to keep the digital noise from coupling

into the analog portions of the circuit. One of the internal lay-

ers of the board is the ground plane layer. This layer is

roughly divided in half with one half of the layer being digital

ground and the other half being analog ground. The other

internal layer is the power plane. It is divided into three sec-

tions; AV

plies are AV

cases (for instance if there is a substantial offset between

AGND and DGND) it may be necessary to tie the two

grounds together on the board. Resistors R2, R8, and R9

provide a means of connecting the two ground planes

together through a low impedance.

A prototype area is provided on the left side of the board.

This area has a small section of analog ground plane in the

center and may be useful for input signal conditioning before

the HI7190.

Reference Circuit

The reference inputs of the HI7190, V

a differential reference input capability. The reference inputs

provide a high impedance dynamic load similar to the analog

inputs. For proper circuit operation these pins must be driven

by low impedance circuitry. Reference noise outside of the

band of interest will be removed by the on chip digital ﬁlter

but excessive reference noise inside the band of interest will

degrade performance of the HI7190.

The actual reference voltage is given by V

The V

tion board which means that V

erence voltage for the HI7190 is 2.5V. Larger values of V

RLO

pin is hard wired to analog ground on the evalua-

, AV

= +5V, AV

, and DV

Application Note

= -5V, and DV

. Nominal values for the sup-

REF

= V

RHI

and V

REF

. The nominal ref-

= +5V. In some

= V

RLO

RHI

, provide

- V

RLO

REF

Related parts for HI7190EVAL

HI7190EVAL Summary of contents

Page 1

... HI7190 data sheet. Hardware Description The HI7190 evaluation board provides the user with a very sim- ple way of interfacing to and evaluating the Intersil HI7190 sigma delta ADC. The board features a reference voltage gen- erator, a crystal oscillator, and digital line drivers and receivers for interfacing running the evaluation software ...

Page 2

HI7190 Functional Block Diagram AV DD TRANSDUCER BURN-OUT CURRENT (100nA) PGIA V INHI V INLO V CM CLOCK GENERATOR OSC OSC 1 2 HI7190 Evaluation Board Block Diagram AIN+ AIN- ON BOARD REFERENCE EXTERNAL V REF Application Note 9505 V ...

Page 3

... U5 on the evaluation board is an “open socket” which is used in conjunction with the test modes of the HI7190 for Intersil internal testing and evaluation. Software Description The software provided with the HI7190 evaluation kit allows the user to operate the device in many of the various modes the part supports. The software is menu driven for ease of use. The simpliﬁ ...

Page 4

Entering s from the Main Menu sends an active low reset signal to the HI7190 which initializes the HI7190. c Entering c from the Main Menu brings the Change Mode Menu up. The Change Mode Menu allows the user ...

Page 5

The Negative Full Scale Calibration Register is 3 bytes. All three bytes must be entered at the prompt. m Entering m from the Write Menu invokes the Main Menu. r Entering r from the Write ...

Page 6

Executing the Program: Change directory (cd) into the directory containing the 7190BTA5.EXE ﬁle. At the DOS prompt type 7190BTA5 [return]. The software reminds the user to apply power to the board before continuing. At this point the software is menu ...

Page 7

Application Note 9505 OSC2 OSC1 7 ...

Page 8

Application Note 9505 DB25 CONNECTOR 8 ...

Page 9

HI7090 Evaluation Board Application Note 9505 COMPONENTS LAYOUT COMPONENT SIDE GROUND PLANES 9 ...

Page 10

HI7090 Evaluation Board (Continued) Application Note 9505 POWER PLANE SOLDER SIDE 10 ...

Page 11

... Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use ...

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