Cirrus Logic CDB5530U User Manual

CDB5530U

CDB5530U Evaluation Board and Software

Features

 USB Communication with PC
 On-board Microcontroller
 On-board Voltage Reference
 Evaluation Software

– Register Setup & Chip Control
– FFT Analysis
– Time Domain Analysis
– Noise Histogram Analysis

 Interface Header for External Microcontroller

CRYSTAL

4.9152 MHz

General Description

The CDB5530U is an inexpensive tool designed to eval­uate the functionality and performance of the CS5530.
The CS5530 data sheet should be read and consulted
when using the CDB5530U evaluation board.

The evaluation board includes a C8051F320 microcon­troller with a USB interface. The microcontroller controls
the serial communication between the evaluation board
and the PC via the firmware, enabling quick and easy ac­cess to all of the CS5530’s registers and functions.

The CDB5530U includes software for Data Capture,
Time Domain Analysis, Histogram Analysis, and Fre­quency Domain Analysis.

ORDERING INFORMATION

CDB5530U Evaluation Board

VA- VA+

GND

VD+

+5 V

AIN1+

AIN1-

VREF+

VREF-

CS5530

AIN1+

AIN1-

CS

SDI

SDO

SCLK

A0
A1

VREF+

VREF-

Interface Header

VREF

Source

Select

LT1019

C8051F320

Microcontroller

RESET

CIRCUITRY

CONNECTOR

USB

http://www.cirrus.com

Copyright © Cirrus Logic, Inc. 2006

(All Rights Reserved)

NOV ‘06

DS742DB1

TABLE OF CONTENTS

1. HARDWARE .............................................................................................................................3

1.1 Introduction ............................ .... ... ... ... ... .... ... .....................................................................3

1.2 Evaluation Board Overview ..................................................................... ... ........................3

1.2.1 Analog Section ....................................... .... ... ... ... .... ... ... ... ..................................... 3

1.2.2 Digital Section ........ ... .... ... ... ....................................... ... ... ... .... ... ... ........................ 4

1.2.3 Power Supply Section ............................................. ... ... ........................................ 4

2. SOFTWARE .............................................................................................................................. 8

2.1 Installation Procedure ...................................................................... .... ... ... ... .... .................8

2.2 Using the Software ................................. .... ... ..................................................................... 8

2.2.1 Start-Up Window ................................................. .... ... ... ........................................ 8

2.2.2 Setup Window .......................................................................................................9

2.2.3 Data Collection Window ......................................................................................12

2.2.4 Configuration Window ................................................ ... ... ................................... 13

2.3 Collecting Data Sets ........................................................................................................14

2.4 Saving and Printing Data .................................................................................................14

2.5 Retrieving Saved Data From a File ..................................................................................14

2.6 Analyzing Data ....... .......................................... ... .... .......................................... ... ............14

2.7 Histogram Information ......................................................................................................15

2.8 Frequency Domain Information ..................... ... ... .... ...................................... .... ... ... ... ......15

2.9 Time Domain Information ................................................................................................. 15

3. BOARD LAYOUT ................................................................................................................... 16

CDB5530U

LIST OF FIGURES

Figure 1. Analog Section................................................................................................................. 5

Figure 2. Digital Section .................................................................................................................. 6

Figure 3. Power Supply................................................................................................................... 7

Figure 4. Evaluation Software Start-Up Screen .............................................................................. 8

Figure 5. CDB5530U Setup Window............................................................................................... 9

Figure 6. CDB5530U Calibration Window.....................................................................................10

Figure 7. CDB5530U Data Collection Window..............................................................................12

Figure 8. CDB5530U Configuration Window.................................................................................13

Figure 10. Top Silkscreen .............................................................................................................16

Figure 11. Top Side Layout...........................................................................................................17

Figure 12. Bottom Silkscreen........................................................................................................18

Figure 13. Bottom Side Layout...................................................................................................... 19

LIST OF TABLES

Table 1. Voltage Reference Selection for VREF+ ..........................................................................4

Table 2. Voltage Reference Selection for VREF- ...........................................................................4

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CDB5530U

1. HARDWARE

1.1 Introduction

The CDB5530U evaluation board provides a quick means of evaluating the CS5530 Analog-to-Digital
Converter (ADC). The CS5530 is a highly integrated ∆Σ ADC which uses charge-balance techniques to
achieve 24-bit performance. The CS5530 includes a very low noise chopper-stabilized instrumentation
amplifier (12 nV/sqrt(Hz) @ 0.1 Hz) with a fixed gain of 64×. This ADC also includes a fourth-order ∆Σ
modulator followed by a digital filter which provides twenty selectable output word rates of 6.25 Hz,

7.5 Hz, 12.5 Hz, 15 Hz, 25 Hz, 30 Hz, 50 Hz, 60 Hz, 100 Hz, 120 Hz, 200 Hz, 240 Hz, 400 Hz, 480 Hz,
800 Hz, 960 Hz, 1.6 kHz, 1.92 kHz, 3.2 k Hz and 3.84 kHz (XIN = 4.9152 MHz).

1.2 Evaluation Board Overview

The CDB5530U evaluation board is partitioned into two main sections — analog and digital. The analog
section consists of the CS5530 and a precision voltage reference. The digital section consists of the mi­crocontroller, the reset circuitry, and the USB interface. The board also has power supply connections
which accommodate all of the various supply options of the CS5530.

The evaluation board’s analog section operates from either a single +5 V, dual ±2.5 V, or dual ±3 V power
supply. The evaluation board interfaces the CS5530 to an IBM
accomplish this, the board comes equipped with a microcontroller and a USB cable which physically in­terfaces the evaluation board to the PC. The software provides easy access to the internal registers of the
CS5530, and provides a means to display and evaluate the performance of the ADC in the time domain
or the frequency domain.

®

compatible PC with a USB interface. To

1.2.1 Analog Section

The CS5530 is a high-precision ∆Σ converter designed to accurately measure one fully differential analog
voltage input while operating from a 4.9152 MHz crystal.

The evaluation board provides screw terminals labeled AIN1+ & AIN1- to connect input signals to the sin­gle input channel. The sensor’s output is filtered by a simple RC network at the channel input to reduce
any interference picked up by the input leads. The 3 dB corner of the filter is approximately 52 kHz, differ­ential and 56 kHz, common mode. Figure 1 illustrates the schematic of the analog section.

The evaluation board provides three voltage reference options for VREF+ and VREF-. The three refer­ence options for VREF+ include: VA+, the on-board LT1019 voltage reference, and external input (J12).
Table 1 illustrates the options available. With the J17 jumper in the VA+ position, the reference is supplied
by the VA+ analog supply. With the J17 jumper in the LT1019 position, the LT1019 provides a +2.5 V ref­erence (the LT1019 was chosen for its low drift, typically 5ppm/°C). By setting the J17 jumper to the
VREF+ position, the user can supply an external voltage reference to J12’s VREF+ input.

The three reference options for VREF- include: VA-, GND, and external input (J12). Table 2 illustrates the
options available. With the J18 jumper in the VA- position, the reference is supplied by the VA- analog
supply. With the J18 jumper in the GND position, the VREF- pin is connected to the board ground. By
setting the J18 jumper to the VREF- position, the user can supply an external voltage reference to J12’s
VREF- input.

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CDB5530U

Table 1. Voltage Reference Selection for VREF+ Table 2. Voltage Reference Selection for VREF-

Reference Description J17

VA+

LT1019

VREF+

Selects Positive

Analog Power

Supply

Selects on-Board

LT1019 Reference

(5ppm/

°C)

Selects External

Reference Source

(J12)

VA+
LT1019
REF+

VA+
LT1019
REF+

VA+
LT1019
REF+

O O VREF+
O O VREF+
O O VREF+

O O VREF+
O O VREF+
O O VREF+

O O VREF+
O O VREF+
O O VREF+

Reference Description J18

VA-

GND

VREF-

Selects Negative

Analog Power

Supply

Selects Board

Gnd

Selects External

Reference Source

(J12)

VA­ GND
REF-

VA­ GND
REF-

VA­ GND
REF-

O O VREF­O O VREF­O O VREF-

O O VREF­O O VREF­O O VREF-

O O VREF­O O VREF­O O VREF-

1.2.2 Digital Section

Figure 2 illustrates the schematic of the digital section. It contains the microcontroller, USB interface, EE­PROM, JTAG header, reset circuitry, and an external interface header. The microcontroller interfaces the

™

SPI

and MICROWIRE™ compatible serial port of the CS5530 with the USB connection to the PC. Note

that the SCLK and SDI signals are level shifted to support both +3.3 V and +5 V digital operation.
The microcontroller EEPROM is used to store firmware. An external interface header, J19, is provided to

allow the CDB5530U to be interfaced with an external microcontroller. To use this serial interface, the
0 ohm resistors R9, R10, R23, and R27 should be removed to disconnect the on-board microcontroller
from the serial interface.

1.2.3 Power Supply Section

Figure 3 illustrates the power supply connections to the evaluation board. VA+ supplies the positive ana­log supply for the CS5530 and the LT1019 reference. Header J14 allows the VA+ supply to be sourced
from either the VA+ binding post (J2), or from the +5 V binding post (J3). VA- supplies the negative analog
supply for the analog section. Header J13 allows the VA- supply to be sourced from either the VA- binding
post (J1), or connected to the board ground. Note that the VA- supply should be connected to ground
when powering the CDB5530U from a single +5 V analog supply. VD+ supplies the digital section of the
ADC and level shifters. Header J15 allows the VD+ supply to be sourced from the VD+ binding post (J5),
the +5 V binding post (J3), or the regulated +3.3 V supply derived from the microcontroller. The +5 V bind­ing post supplies the microcontroller’s internal regulator.

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CDB5530U

Figure 1. Analog Section

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CDB5530U

Figure 2. Digital Section

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