NAU7802 24-bit ADC
NAU7802
24-Bit Dual-Channel ADC
For Bridge Sensors
Date: January, 2012
Revision 1.7
Nuvoton Confidential
-1-
Revision 1.7
NAU7802 24-bit ADC
Table of Contents
1
2
3
4
5
6
7
GENERAL DESCRIPTION ......................................................................................................... 4
SYSTEM BLOCK DIAGRAM ...................................................................................................... 4
FEATURES ................................................................................................................................. 4
APPLICATIONS .......................................................................................................................... 5
PIN CONFIGURATION ............................................................................................................... 6
PIN DESCRIPTION ..................................................................................................................... 6
ELECTRICAL CHARACTERISTICS ........................................................................................... 7
7.1
Absolute Maximum Ratings ............................................................................................ 7
7.2
DC ELECTRICAL CHARACTERISTICS ........................................................................ 7
7.3
RC OSC AND AC CHARACTERISTICS ........................................................................ 9
7.4
TEMPERATURE SENSOR............................................................................................. 9
7.5
Typical Characteristic .................................................................................................... 10
7.5.1
7.5.2
7.5.3
NAU7802 Linearity – (Error % vs. Input Voltage) ............................................................10
Noise Performance – NAU7802 ......................................................................................11
ESD Performance – NAU7802 ........................................................................................11
8
7.6
DIGITAL SERIAL INTERFACE TIMING ....................................................................... 12
FUNCTIONAL DESCRIPTION .................................................................................................. 13
8.1
Analog input (VIN1P, VIN1N, VIN2N, VIN2P) .............................................................. 13
8.2
Power supply ................................................................................................................ 13
2
8.3
2-Wire-Serial Control and Data Bus (I C Style Interface) ............................................ 13
8.3.1
8.3.2
8.3.3
2-Wire Protocol Convention ............................................................................................14
2-Wire Write Operation ...................................................................................................16
2-Wire Single Read Operation ........................................................................................16
8.4
8.5
2-Wire Timing ................................................................................................................ 17
NAU7802 Streaming Data Mode .................................................................................. 18
8.5.1
8.5.2
8.5.3
Enabling the Streaming I2C Mode ..................................................................................18
Streaming I2C Mode R/W Protocol 1 ..............................................................................18
Streaming I2C Mode R/W Protocol 2 ..............................................................................19
Internal or External calibration.........................................................................................20
Calibration Limitations .....................................................................................................21
Calibration Error ..............................................................................................................21
8.6
Device Calibration Features ......................................................................................... 20
8.6.1
8.6.2
8.6.3
8.7
8.8
8.9
8.10
Internal Band-Gap Circuit
................................................................................................ 22
Reset and Power-down mode ...................................................................................... 22
Temperature sensor ...................................................................................................... 23
Oscillator Features ........................................................................................................ 24
8.10.1
8.10.2
External Crystal Oscillator .............................................................................................24
External Clock Source...................................................................................................24
9
APPLICATION INFORMATION ................................................................................................ 25
9.1
Power-On Sequencing .................................................................................................. 25
9.2
Signal path normal operation ........................................................................................ 25
9.3
Signal path with PGA bypass enabled .......................................................................... 26
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Revision 1.7
Nuvoton Confidential
NAU7802 24-bit ADC
10
11
9.4
16-pin application circuit ............................................................................................... 27
SUMMARY DEVICE REGISTER MAP ..................................................................................... 28
DEVICE REGISTER MAP DETAILS......................................................................................... 29
11.1 REG0x00:PU_CTRL ..................................................................................................... 29
11.2 REG0x01:CTRL1 .......................................................................................................... 30
11.3 REG0x02:CTRL2 .......................................................................................................... 31
11.4 REG0x03-REG0x05: Channel 1 OFFSET Calibration ................................................. 32
11.5 REG0x06-REG0x09: Channel 1 GAIN Calibration ....................................................... 32
11.6 REG0x0A-REG0x0C: Channel 2 OFFSET Calibration (NAU7802 - only) ................... 32
11.7 REG0x0D-REG0x10: Channel 2 GAIN Calibration (NAU7802 - only) ......................... 32
11.8 REG0x11: I2C Control .................................................................................................. 33
11.9 REG0x12-REG0x14: ADC Conversion Result ............................................................. 34
11.10
REG0x15: ADC registers .......................................................................................... 35
REG0x15-REG0x17: OTP Read Value and REG0x15 ADC Registers Read .......................... 36
11.11
REG0x18: Read Only ............................................................................................... 36
11.12
REG0x19: Read Only ............................................................................................... 36
11.13
REG0x1A: Read Only............................................................................................... 36
11.14
REG0x1B: PGA Registers ........................................................................................ 36
11.15
REG0x1C: POWER CONTROL Register ................................................................. 37
11.15.1
11.15.2
11.15.3
REG0x1D: Read Only .................................................................................................37
REG0x1E: Read Only .................................................................................................37
REG0x1F: Read Only .................................................................................................37
12
13
14
PACKAGE DIMENSIONS ......................................................................................................... 38
12.1 16L SOP – 150 mil ........................................................................................................ 38
12.2 PDIP16L - 300 mil ......................................................................................................... 39
PART ORDERING INFORMATION .......................................................................................... 40
REVISION HISTORY ................................................................................................................ 41
Nuvoton Confidential
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Revision 1.7
NAU7802 24-bit ADC
1
GENERAL DESCRIPTION
The Nuvoton NAU7802 is a precision low-power 24-bit analog-to-digital converter (ADC), with an
onboard low-noise programmable gain amplifier (PGA), onboard RC or Crystal oscillator, and a
precision 24-bit sigma-delta (Σ-Δ) analog to digital converter (ADC). The NAU7802 device is capable of
up to 23-bit ENOB (Effective Number Of Bits) performance. This device provides a complete front-end
solution for bridge/sensor measurement such as in weigh scales, strain gauges, and many other high
resolution, low sample rate applications.
The many built-in features enable high performance applications with very low external parts count.
Additionally, both operating current and standby current are very low, and many power management
features are included. These enable powering only those elements of the chip that are needed, and
also, to operate at greatly reduced power if the full 23-bit ENOB performance is not required.
The Programmable Gain Amplifier (PGA) provides selectable gains from 1 to 128. The A/D conversion
is performed with a Sigma-Delta modulator and programmable FIR filter that provides a simultaneous
50Hz and 60Hz notch filter to effectively improve interference immunity. Also, this device provides a
standard 2-wire interface compatible with I2C protocol for simple and straightforward connection to and
interoperation with a wide range of possible host processors.
2
SYSTEM BLOCK DIAGRAM
2.7V~5.5V Input
DVDD
To serial
Interface
IO Power
1
VBG
AVDD
XIN
XOUT
Bandgap
Reference
LDO
To
Analog
Circuit
LDO
VLDO [1:0]
0
Internal RC
Oscillator
digital logic
Control Signal
OSCS
CHS
CRS[2:0]
PGA[1:0]
14
SDIO
SCLK
Digital
DRDY
VIN1P
VIN2P
VIN1N
VIN2N
PGA
24- bit ADC
ADC result
Interface
24
Temperature
Sensor
AVSS
REFP
REFN
DVSS
Nuvoton Confidential
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Revision 1.7
NAU7802 24-bit ADC
3
FEATURES
Supply power: 2.7V~5.5V
On-chip VDDA regulator for internal analog circuit or external load cell
Programmable VDDA: Off, 2.4V to 4.5V with eight options
Minimum 10mA output drive capability at 3.0V output voltage
Note: DVDD must be 0.3Vdc greater than desired VDDA output voltage
23 bits effective precision analog-to-digital converter
Simultaneous 50Hz and 60Hz rejection (reaching
－90dB）
RMS Noise:
50nV in 10 SPS data output rate and PGA gain = 128
150nV in 80 SPS data output rate and PGA gain = 128
Programmable PGA gains from 1 to 128
Programmable ADC data output rates
External differential reference voltage range from 0.1V to 5V
System clock: External crystal oscillator or on-chip RC oscillator (4.9152Mhz)
On-chip calibration
On-chip power-on reset circuit
On-chip temperature sensor
Low Power Consumption and Programmable Power Management Options
< 1uA standby current
External 4.9152MHz Crystal oscillator
System clock:
Internal 4.9152MHz RC oscillator (power-on default system clock)
External 4.9152MHz Crystal oscillator
MCU control interface: 2-wire interface compatible with I2C protocol
Operating Temperature: -40~85C
Packages:
SOP-16 (150mil) / PDIP-16
4
APPLICATIONS
Weigh scales
Strain Gauge
Industrial process control
Liquid/gas flow control
Pressure sensors
Voltage monitors
Nuvoton Confidential
-5-
Revision 1.7
微控制器 MCU
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