18-Bit ADC with I2C Interface and Onboard Reference DS

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© 2009 Microchip Technology Inc.

DS22226A-page 1

MCP3426/7/8

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

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

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.

16-Bit, Multi-Channel 

ΔΣ Analog-to-Digital Converter with 

I

2

C™ Interface and On-Board Reference

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MCP3426/7/8

DS22226A-page 2

© 2009 Microchip Technology Inc.

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

MCP3426

 

Functional Block Diagram 

4

5

6

9

CH2-

 V

SS

CH3+

Adr1

Adr0

3

12

CH2+

CH3-

2

13

CH1-

CH4+

1

14

CH1+

CH4-

7

8

 SDA

SCL

 V

DD

MCP3428

11

10

SOIC, TSSOP

2

3

4

7

8

9

CH1-

V

DD

SDA

Adr0

 V

SS

SCL

1

10

CH1+

Adr1

5

6

CH2-

CH2+

MCP342

7

2

3

4

5

6

7

CH1-

V

DD

SDA

CH2+

V

SS

SCL

1

8

CH1+

CH2-

MC

P

3

426

MSOP, SOIC

MSOP

MCP3426

2x3 DFN *

V

DD

CH1-

SDA

CH2+

V

SS

1

2

3

4

8

7

6

5 SCL

CH2-

CH1+

* Includes Exposed Thermal Pad (EP); see 

Table 3-1

.

EP

9

MCP3427

3x3 DFN *

V

SS

CH1-

CH2+

Adr0

SCL

1

2

3

4

10

9

8

7 SDA

Adr1

CH1+

EP

11

CH2-

5

6 V

DD

V

SS

V

DD

PGA

SCL

SDA

MU

X

I

2

C

Interface

Gain = 1, 2, 4, or 8

Voltage Reference

Clock

(2.048V)

V

REF

ΔΣ ADC

Converter

Oscillator

MCP3426

CH1+

CH1-

CH2+

CH2-

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DS22226A-page 3

MCP3426/7/8

MCP3427 Functional Block Diagram 

MCP3428 Functional Block Diagram 

V

SS

V

DD

CH1+

CH1-

PGA

SCL

SDA

MUX

I

2

C

Interface

Gain = 1, 2, 4, or 8

Adr1

Adr0

CH2+

CH2-

Voltage Reference

Clock

(2.048V)

V

REF

ΔΣ ADC

Converter

Oscillator

MCP3427

V

SS

V

DD

CH1+

CH1-

PGA

SCL

SDA

MUX

I

2

C

Interface

Gain = 1, 2, 4, or 8

Adr1

Adr0

CH2+

CH2-

CH3+

CH3-

CH4+

CH4-

Voltage Reference

Clock

(2.048V)

V

REF

ΔΣ ADC

Converter

Oscillator

MCP3428

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MCP3426/7/8

DS22226A-page 4

© 2009 Microchip Technology Inc.

NOTES:

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DS22226A-page 5

MCP3426/7/8

1.0

ELECTRICAL 
CHARACTERISTICS

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

†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

.

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

Sym

 Min

 Typ

 Max

Units

             Conditions

Analog Inputs 

Differential Full Scale Input 
Voltage Range

FSR

±2.048/PGA

V

V

IN

 = [CHn+ - CHn-]

Maximum Input Voltage Range

V

SS

-0.3

V

DD

+0.3

V

(Note 1)

Differential Input Impedance 

Z

IND

 (f)

2.25/PGA

M

Ω

During normal mode operation
(Note 2)

Common Mode input 
Impedance

Z

INC

 (f)

25

M

Ω

PGA = 1, 2, 4, 8

System Performance

Resolution and No Missing 
Codes 
(Effective Number of Bits)
(Note 3)

12

Bits

DR = 240 SPS

14

Bits

DR = 60 SPS

16

Bits

DR = 15 SPS

Data Rate 
(Note 4)

DR

176

240

328

SPS

12 bits mode

44

60

82

SPS

14 bits mode

11

15

20.5

SPS

16 bits mode

Output Noise

2.5

µV

RMS

T

A

 = +25°C, DR =15 SPS,   

PGA = 1, V

IN

+ = V

IN

- = GND 

Integral Non-Linearity

INL

10

ppm of 

FSR

DR = 15 SPS
(Note 5)

Internal Reference Voltage

V

REF

2.048

V

Gain Error (Note 6)

0.1

%

PGA = 1, DR = 15 SPS

PGA Gain Error Match (Note 6)

0.1

%

Between any 2 PGA settings

Gain Error Drift (Note 6)

15

ppm/°C

PGA=1, DR=15 SPS

Note

1:

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”).

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MCP3426/7/8

DS22226A-page 6

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Offset Error

V

OS

30

µV

PGA = 1
DR = 15 SPS

Offset Drift vs. Temperature

50

nV/°C

Common-Mode Rejection 

105

dB

at DC and PGA =1,

110

dB

at DC and PGA =8, T

A

 = +25°C

Gain vs. V

DD

5

ppm/V

T

A

 = +25°C, V

DD

 = 2.7V to 5.5V,

PGA = 1

Power Supply Rejection at DC 
Input

100

dB

T

A

 = +25°C, V

DD

 = 2.7V to 5.5V,

PGA = 1

Power Requirements

Voltage Range

V

DD

2.7

5.5

V

Supply Current during 
Conversion

I

DDA

145

180

µA

V

DD

 = 5.0V

135

µA

V

DD

 = 3.0V

Supply Current during Standby 
Mode

I

DDS

0.3

1

µA

V

DD

 = 5.0V

I

2

C Digital Inputs and Digital Outputs

High level input voltage

V

IH

0.7V

DD

V

DD

V

at SDA and SCL pins

Low level input voltage

V

IL

0.3V

DD

V

at SDA and SCL pins

Low level output voltage

V

OL

0.4

V

I

OL

 = 3 mA

Hysteresis of Schmidt Trigger 
for inputs (Note 7)

V

HYST

0.05V

DD

V

f

SCL

 = 100 kHz

Supply Current when I

2

C bus 

line is active

I

DDB

10

µA

Device is in standby mode while 
I

2

C bus is active

Input Leakage Current

I

ILH

1

µA

V

IH

 = 5.5V

I

ILL

-1

µA

V

IL

 = GND

Logic Status of I

2

C Address Pins (Note 8)

Adr0 and Adr1 Pins

Addr_Low

V

SS

0.2V

DD

V

The device reads logic low.

Adr0 and Adr1 Pins

Addr_High

0.75V

DD

V

DD

V

The device reads logic high.

Adr0 and Adr1 Pins

Addr_Float

0.35V

DD

0.6V

DD

V

Read pin voltage if voltage is 
applied to the address pin. 
(Note 9
)

V

DD

/2

Device outputs float output 
voltage (V

DD

/2) on the address 

pin, if left “floating”. (Note 10)

Pin Capacitance and I

2

C Bus Capacitance

Pin capacitance 

C

PIN

4

10

pF

I

2

C Bus Capacitance

C

b

400

pF

ELECTRICAL CHARACTERISTICS (CONTINUED)

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

Sym

 Min

 Typ

 Max

Units

             Conditions

Note

1:

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”).

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DS22226A-page 7

MCP3426/7/8

TEMPERATURE CHARACTERISTICS

Electrical Specifications: Unless otherwise indicated, 

T

A

 = -40°C to +125°C, V

DD

 = +5.0V, V

SS

 = 0V.

Parameters

Sym

Min

Typ

Max

Units

Conditions

Temperature Ranges

Specified Temperature Range

T

A

-40

+85

°C

Operating Temperature Range

T

A

-40

+125

°C

Storage Temperature Range

T

A

-65

+150

°C

Thermal Package Resistances

Thermal Resistance, 8L-DFN (2x3)

θ

JA

84.5

°C/W

Thermal Resistance, 8L-MSOP

θ

JA

211

°C/W

Thermal Resistance, 8L-SOIC

θ

JA

149.5

°C/W

Thermal Resistance, 10L-DFN (3x3)

θ

JA

57

°C/W

Thermal Resistance, 10L-MSOP

θ

JA

202

°C/W

Thermal Resistance, 14L-SOIC

θ

JA

120

°C/W

Thermal Resistance, 14L-TSSOP

θ

JA

100

°C/W

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NOTES:

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DS22226A-page 9

MCP3426/7/8

2.0

TYPICAL PERFORMANCE CURVES

Note: Unless otherwise indicated, T

A

 = -40°C to +85°C, V

DD

 = +5.0V, V

SS

 = 0V, CHn+ = CHn- = V

REF

/2,

V

INCOM

 = V

REF

/2.

 

FIGURE 2-1:

INL vs. Supply Voltage 

(V

DD

).

FIGURE 2-2:

INL vs. Temperature.

FIGURE 2-3:

Offset Error vs. 

Temperature.

FIGURE 2-4:

Output Noise vs. Input 

Voltage.

FIGURE 2-5:

Total Error vs. Input Voltage.

FIGURE 2-6:

Gain Error vs. Temperature.

Note:

The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.

0

0.001

0.002

0.003

0.004

0.005

2.5

3

3.5

4

4.5

5

5.5

V

DD 

(V)

In

teg

ral N

o

n

lin

ear

ity

 (% F

S

R

)

PGA = 1

PGA = 4

PGA = 8

PGA = 2

0

0.001

0.002

0.003

0.004

0.005

-60 -40 -20

0

20

40

60

80 100 120 140

Temperature (

o

C)

IN

L

 (% 

F

S

R

)

2.7V

5V

-25

-20

-15

-10

-5

0

5

10

15

20

-40 -20

0

20

40

60

80 100 120 140

Temperature (

o

C)

O

ff

s

e

t E

rror 

V

)

V

DD

 = 5V

PGA = 1

PGA = 2

PGA = 4

PGA = 8

0

2

4

6

8

10

12

-100

-75

-50

-25

0

25

50

75

100

Input Signal (% of FSR)

O

u

tp

ut

 N

o

ise (

µ

V

rm

s)

PGA  = 1

PGA  = 8

PGA  = 4

PGA  = 2

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-100

-75

-50

-25

0

25

50

75

100

Input Voltage (% of Full-Scale)

T

o

ta

l E

rr

o

r (m

V

)

PGA = 1

PGA = 8

PGA = 4

PGA  = 2

T

A

= +25°C

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

-60 -40 -20

0

20

40

60

80 100 120 140

Temperature (°C)

G

a

in

 E

rro

r (

%

 o

f F

S

R

)

PGA = 1

PGA = 2

PGA = 4

PGA = 8 

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MCP3426/7/8

DS22226A-page 10

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Note: Unless otherwise indicated, T

A

 = -40°C to +85°C, V

DD

 = +5.0V, V

SS

 = 0V, CHn+ = CHn- = V

REF

/2,

V

INCOM

 = V

REF

/2.

FIGURE 2-7:

I

DDA

 vs. Temperature.

FIGURE 2-8:

I

DDS

 vs. Temperature.

FIGURE 2-9:

I

DDB

 vs. Temperature.

FIGURE 2-10:

Oscillator Drift vs. 

Temperature.

FIGURE 2-11:

Frequency Response.

60

80

100

120

140

160

180

200

-60

-40

-20

0

20

40

60

80

100 120 140

Temperature (°C)

I

DD

A

 

A

)

V

DD

 = 5.5V

V

DD

 = 5.0V

V

DD

 = 2.7V

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-60 -40 -20

0

20

40

60

80 100 120 140

Temperature (°C)

I

DDS

 (µ

A

)

V

DD

 = 2.7V

V

DD

 = 5.0V

V

DD

 = 5.5V

0

2

4

6

8

10

12

14

-60 -40 -20

0

20

40

60

80 100 120 140

Temperature (°C)

I

DD

B

 (µ

A

)

V

DD

 = 5.5V

V

DD

 = 5.0V

V

DD

 = 4.5V

V

DD 

= 2.7V

-1

0

1

2

3

4

5

-60 -40 -20

0

20

40

60

80 100 120 140

Temperature (°C)

Osci

llato

r D

ri

ft 

(%

)

V

DD

 = 5.0V

V

DD

 = 2.7V

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

0.1

1

10

100

1000

10000

Input Signal Frequency (Hz)

M

a

gni

tude (dB)

Data Rate = 15 SPS

10k

1k

Maker
Microchip Technology Inc.