Microchip Technology MCP3422, Manual

Page: 1 / 56

©
2008 Microchip Technology Inc. DS22088B-page 1
MCP3422/3/4
Features
• 18-bit
ΔΣ
ADC with Differential Inputs:
- 2 channels: MCP3422 and MCP3423
- 4 channels: MCP3424
• Differential Input Full-Scale Range: -V
REF
to
+V
REF
• Self Calibration of Internal Offset and Gain per
Each Conversion
• On-Board Voltage Reference (V
REF
):
- Accuracy: 2.048V ± 0.05%
- Drift: 15 ppm/°C
• On-Board Programmable Gain Amplifier (PGA):
- Gains of 1,2, 4 or 8
• INL: 10 ppm of Full-Scale Range
• Programmable Data Rate Options:
- 3.75 SPS (18 bits)
- 15 SPS (16 bits)
- 60 SPS (14 bits)
- 240 SPS (12 bits)
• One-Shot or Continuous Conversion Options
• Low Current Consumption:
- 135 µA typical
(V
DD
= 3V, Continuous Conversion)
- 36 µA typical
(V
DD
= 3V, One-Shot Conversion with 1 SPS)
• On-Board Oscillator
• I
2
C
™
Interface:
- Standard, Fast and High Speed Modes
- User configurable two external address pins
for MCP3423 and MCP3424
• Single Supply Operation: 2.7V to 5.5V
• Extended Temperature Range: -40°C to +125°C
Typical Applications
• Portable Instrumentation and Consumer Goods
• Temperature Sensing with RTD, Thermistor, and
Thermocouple
• Bridge Sensing for Pressure, Strain, and Force
• Weigh Scales
• Battery Fuel Gauges
• Factory Automation Equipment
Description
The MCP3422, MCP3423 and MCP3424 devices
(MCP3422/3/4) are the low noise and high accuracy
18-Bit delta-sigma analog-to-digital (
ΔΣ
A/D) converter
family members of the MCP342X series from Microchip
Technology Inc. These devices can convert analog
inputs to digital codes with up to 18 bits of resolution.
The on-board 2.048V reference voltage enables an
input range of
±
2.048V differentially (full-scale
range = 4.096V/PGA).
These devices can output analog-to-digital conversion
results at rates of 3.75, 15, 60, or 240 samples per
second depending on the user controllable configura-
tion bit settings using the two-wire I
2
C serial interface.
During each conversion, the device calibrates offset
and gain errors automatically. This provides accurate
conversion results from conversion to conversion over
variations in temperature and power supply fluctuation.
The user can select the PGA gain of x1, x2, x4, or x8
before the analog-to-digital conversion takes place.
This allows the MCP3422/3/4 devices to convert a very
weak input signal with high resolution.
The MCP3422/3/4 devices have two conversion
modes: (a) One-Shot Conversion mode and (b) Contin-
uous Conversion mode. In One-Shot conversion mode,
the device performs a single conversion and enters a
low current standby mode automatically until it receives
another conversion command. This reduces current
consumption greatly during idle periods. In Continuous
conversion mode, the conversion takes place
continuously at the set conversion speed. The device
updates its output buffer with the most recent
conversion data.
The devices operate from a single 2.7V to 5.5V power
supply and have a two-wire I
2
C compatible serial inter-
face for a standard (100 kHz), fast (400 kHz), or
high-speed (3.4 MHz) mode.
The I
2
C address bits for the MCP3423 and MCP3424
are selected by using two external I
2
C address selec-
tion pins (Adr0 and Adr1). The user can configure the
device to one of eight available addresses by connect-
ing these two address selection pins to V
DD
, V
SS
or
float. The I
2
C address bits of the MCP3422 are pro-
grammed at the factory during production.
18-Bit, Multi-Channel
ΔΣ
Analog-to-Digital Converter with
I
2
C™ Interface and On-Board Reference