MCP3426/7/8
16-Bit, Multi-Channel
ΔΣ
Analog-to-Digital Converter with
I
2
C™ Interface and On-Board Reference
Features
• 16-bit
ΔΣ
ADC with Differential Inputs:
- 2 channels: MCP3426 and MCP3427
- 4 channels: MCP3428
• 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:
- 15 SPS (16 bits)
- 60 SPS (14 bits)
- 240 SPS (12 bits)
• One-Shot or Continuous Conversion Options
• Low Current Consumption (V
DD
= 3V):
- Continuous Conversion: 135 µA typical
- One-Shot Conversion with 1 SPS:
- 9 µA typical for 16 bit mode
- 2.25 µA typical for 14 bit mode
- 0.56 µA typical for 12 bit mode
• On-Board Oscillator
• I
2
C
™
Interface:
- Standard, Fast and High Speed Modes
- User configurable two external address
selection pins for MCP3427 and MCP3428
• Single Supply Operation: 2.7V to 5.5V
• Extended Temperature Range: -40°C to +125°C
Description
The MCP3426, MCP3427 and MCP3428 devices
(MCP3426/7/8) are the low noise and high accuracy
16 Bit Delta-Sigma Analog-to-Digital (ΔΣ A/D) Con-
verter family members of the MCP342X series from
Microchip Technology Inc. These devices can convert
analog inputs to digital codes with up to 16 bits of reso-
lution.
The MCP3426 and MCP3427 devices have two
differential input channels and the MCP3428 has four
differential input channels. All electrical properties of
these three devices are the same except the
differences in the number of input channels and I
2
C
address bit selection options.
These devices can output analog-to-digital conversion
results at rates of 15 (16-bit mode), 60 (14-bit mode), or
240 (12-bit mode) samples per second depending on
the user controllable configuration 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 device has an on-board 2.048V reference voltage,
which enables an input range of ± 2.048V differentially
(full scale range = 4.096/PGA).
The user can select the gain of the on-board
programmable gain amplifier (PGA) using the
configuration register bits (gain of x1, x2, x4, or x8).
This allows the MCP3426/7/8 devices to convert a very
weak input signal with high resolution.
The MCP3426/7/8 devices have two conversion
modes: (a) One-Shot Conversion mode and
(b) Continuous Conversion mode. In the One-Shot
conversion mode, the device performs a single
conversion and enters a low current standby
(shutdown) 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 configured 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
interface for a standard (100 kHz), fast (400 kHz), or
high-speed (3.4 MHz) mode.
Typical Applications
• Portable Instrumentation and Consumer Goods
• Temperature Sensing with RTD, Thermistor, and
Thermocouple
• Bridge Sensing for Pressure, Strain, and Force
• Weigh Scales and Battery Fuel Gauges
• Factory Automation Equipment
©
2009 Microchip Technology Inc.
DS22226A-page 1
MCP3426/7/8
The I
2
C address bits for the MCP3427 and MCP3428
are selected by using two external I
2
C address
selection pins (Adr0 and Adr1). The user can configure
the device to one of eight available addresses by
connecting these two address selection pins to V
DD
,
V
SS
or float. The I
2
C address bits of the MCP3426 are
programmed at the factory during production.
The MCP3426 is available in 8-pin SOIC, DFN, and
MSOP packages. The MCP3427 is available in 10-pin
DFN, and MSOP packages. The MCP3428 is available
in 14-pin SOIC and TSSOP packages.
Package Types
MSOP, SOIC
CH1+ 1
CH1- 2
V
DD
3
SDA 4
8 CH2-
7 CH2+
6 V
SS
5 SCL
CH1+ 1
CH1- 2
V
SS
CH2+
CH2-
3
4
5
MSOP
10 Adr1
CH1+ 1
CH1-
2
SOIC, TSSOP
14 CH4-
13 CH4+
12 CH3-
11 CH3+
10 Adr1
9
8
Adr0
SCL
9
MCP3427
MCP3426
2x3 DFN *
CH1+
1
CH1-
2
MCP3426
EP
9
Adr0
8 SCL
7 SDA
6 V
DD
MCP3428
CH2+ 3
CH2- 4
V
SS
5
V
DD
6
7
MCP3427
3x3 DFN *
CH1+
1
CH1-
2
V
SS
3
CH2+
4
CH2-
5
SDA
8
CH2-
7
CH2+
6 V
SS
5 SCL
10
Adr1
EP
11
9
Adr0
8 SCL
7 SDA
6 V
DD
V
DD
3
SDA 4
* Includes Exposed Thermal Pad (EP); see
Table 3-1.
MCP3426 Functional Block Diagram
V
SS
MCP3426
V
DD
Voltage Reference
(2.048V)
V
REF
CH1+
MUX
CH1-
CH2+
CH2-
PGA
ΔΣ
ADC
Converter
I C
Interface
2
SCL
SDA
Gain = 1, 2, 4, or 8
Clock
Oscillator
DS22226A-page 2
©
2009 Microchip Technology Inc.
MCP3426/7/8
1.0
ELECTRICAL
CHARACTERISTICS
†Notice:
Stresses above those listed under “Maximum Rat-
ings” may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operational listings of this specification is not implied.
Exposure to maximum rating conditions for extended periods
may affect device reliability
.
Absolute Maximum Ratings†
V
DD
...................................................................................7.0V
All inputs and outputs ............. ..........V
SS
–0.4V to V
DD
+0.4V
Differential Input Voltage ...................................... |V
DD
- V
SS
|
Output Short Circuit Current ................................ Continuous
Current at Input Pins ....................................................±2 mA
Current at Output and Supply Pins ............................±10 mA
Storage Temperature ....................................-65°C to +150°C
Ambient Temp. with power applied ...............-55°C to +125°C
ESD protection on all pins
................ ≥
6 kV HBM,
≥
400V MM
Maximum Junction Temperature (T
J
). .........................+150°C
ELECTRICAL CHARACTERISTICS
Electrical Specifications:
Unless otherwise specified, all parameters apply for T
A
= -40°C to +85°C, V
DD
= +5.0V, V
SS
= 0V,
CHn+ = CHn- = V
REF
/2, V
INCOM
= V
REF
/2. All ppm units use 2*V
REF
as differential full scale range.
Parameters
Analog Inputs
Differential Full Scale Input
Voltage Range
Maximum Input Voltage Range
Differential Input Impedance
Common Mode input
Impedance
System Performance
Resolution and No Missing
Codes
(Effective Number of Bits)
(Note 3)
Data Rate
(Note 4)
DR
12
14
16
176
44
11
Output Noise
Integral Non-Linearity
Internal Reference Voltage
Gain Error
(Note 6)
PGA Gain Error Match
(Note 6)
Gain Error Drift (Note
6)
Note 1:
INL
V
REF
—
—
—
—
—
—
—
—
—
240
60
15
2.5
10
2.048
0.1
0.1
15
—
—
—
328
82
20.5
—
—
—
—
—
—
Bits
Bits
Bits
SPS
SPS
SPS
µV
RMS
ppm of
FSR
V
%
%
ppm/°C
PGA = 1, DR = 15 SPS
Between any 2 PGA settings
PGA=1, DR=15 SPS
DR = 240 SPS
DR = 60 SPS
DR = 15 SPS
12 bits mode
14 bits mode
16 bits mode
T
A
= +25°C, DR =15 SPS,
PGA = 1, V
IN
+ = V
IN
- = GND
DR = 15 SPS
(Note 5)
Z
IND
(f)
Z
INC
(f)
FSR
—
V
SS
-0.3
—
—
±2.048/PGA
—
2.25/PGA
25
—
V
DD
+0.3
—
—
V
V
MΩ
MΩ
V
IN
= [CHn+ - CHn-]
(Note 1)
During normal mode operation
(Note 2)
PGA = 1, 2, 4, 8
Sym
Min
Typ
Max
Units
Conditions
Any input voltage below or greater than this voltage causes leakage current through the ESD diodes at the input pins.
This parameter is ensured by characterization and not 100% tested.
2:
This input impedance is due to 3.2 pF internal input sampling capacitor.
3:
This parameter is ensured by design and not 100% tested.
4:
The total conversion speed includes auto-calibration of offset and gain.
5:
INL is the difference between the endpoints line and the measured code at the center of the quantization band.
6:
Includes all errors from on-board PGA and V
REF
.
7:
This parameter is ensured by characterization and not 100% tested.
8:
MCP3427 and MCP3428 only.
9:
Addr_Float voltage is applied at address pin.
10:
No voltage is applied at address pin (left “floating”).
©
2009 Microchip Technology Inc.
DS22226A-page 5
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