CS5550

2

DS630F1

TABLE OF CONTENTS

1. PIN DESCRIPTION ................................................................................................................... 4

2. CHARACTERISTICS/SPECIFICATIONS ................................................................................. 5

ANALOG CHARACTERISTICS ................................................................................................ 5

VOLTAGE REFERENCE.......................................................................................................... 6

5 V DIGITAL CHARACTERISTICS........................................................................................... 7

3 V DIGITAL CHARACTERISTICS........................................................................................... 7

RECOMMENDED OPERATING CONDITIONS ....................................................................... 7

SWITCHING CHARACTERISTICS .......................................................................................... 8

2.1 Theory of Operation ......................................................................................................... 10

2.1.1 High-Rate Digital Low-Pass Filters ..................................................................... 10

2.1.2 Digital Compensation Filters ............................................................................... 10

2.1.3 Gain and Offset Adjustment ................................................................................ 10

2.2 Performing Measurements ............................................................................................... 10

2.3 CS5550 Linearity Performance ........................................................................................ 10

3. FUNCTIONAL DESCRIPTION ............................................................................................... 11

3.1 Analog Inputs ................................................................................................................... 11

3.2 Voltage Reference ........................................................................................................... 11

3.3 Oscillator Characteristics .................................................................................................11

3.4 Calibration ........................................................................................................................ 12

3.4.1 Overview of Calibration Process ......................................................................... 12

3.4.2 Calibration Sequence .......................................................................................... 12

3.4.3 Calibration Signal Input Level ............................................................................. 12

3.4.4 Input Configurations for Calibrations ................................................................... 12

3.4.5 Description of Calibration Algorithms .................................................................. 12

3.4.5.1 Offset Calibration Sequence ............................................................... 12

3.4.5.2 Gain Calibration Sequence ................................................................. 13

3.4.6 Duration of Calibration Sequence ....................................................................... 13

3.5 Interrupt ........................................................................................................................... 13

3.5.1 Typical use of the INT pin ................................................................................... 13

3.5.2 INT Active State .................................................................................................. 13

3.6 PCB Layout ...................................................................................................................... 14

4. SERIAL PORT OVERVIEW .................................................................................................... 15

4.1 Commands ....................................................................................................................... 15

4.2 Serial Port Interface ......................................................................................................... 18

4.3 Serial Read and Write ......................................................................................................18

4.3.1 Register Write ..................................................................................................... 18

4.3.2 Register Read ..................................................................................................... 18

4.4 System Initialization ......................................................................................................... 18

4.5 Serial Port Initialization .................................................................................................... 19

4.6 CS5550 Power States ...................................................................................................... 19

5. REGISTER DESCRIPTION .................................................................................................... 20

5.1 Configuration Register ......................................................................................................20

5.2 Offset Registers ................................................................................................................ 21

5.3 Gain Registers .................................................................................................................. 21

5.4 Cycle Count Register ........................................................................................................21

5.5 OUT1 and OUT2 Output Registers................................................................................... 22

5.6 FILT1, FILT2 Unsigned Output Register........................................................................... 22

5.7 Status Register and Mask Register .................................................................................. 22

5.8 Control Register ................................................................................................................ 23

6. PACKAGE DIMENSIONS ....................................................................................................... 24