Datasheet MCP3550, MCP3551, MCP3553 Datasheet

MCP3550/1/3

V

SS

VIN+

VIN-

SCK

V

DD

SDO

CS

SINC

4

Internal

Serial Interface

V

REF

POR

Oscillator

3rd-Order
DS ADC
Modulator
w/ Internal
Calibration

V

DD

RDY

VIN–

V

IN

+

MCP3550/1/3

V

SS

CS

SDO/RDY

1

2

3

4

8

7

6

5

SCK

V

DD

V

REF

MSOP, SOIC

Low-Power, Single-Channel 22-Bit Delta-Sigma ADCs

Features:

• 22-Bit ADC in Small 8-pin MSOP Package with
Automatic Internal Offset and Gain Calibration

• Low-Output Noise of 2.5 µV
Resolution of 21.9 Bits (MCP3550/1)

• 3 µV Typical Offset Error

• 2 ppm Typical Full Scale Error

• 6 ppm Maximum INL Error

• Total Unadjusted Error Less Than 10 ppm

• No Digital Filter Settling Time, Single-Command
Conversions through 3-wire SPI Interface

• Ultra-Low Conversion Current (MCP3550/1):

-100µA Typical (V

-120µA Typical (VDD = 5.0V)

• Differential Input with V
Range

• 2.7V to 5.5V Single-Supply Operation

• Extended Temperature Range:

- -40°C to +125°C

= 2.7V)

DD

SS

with Effective

RMS

to VDD Common Mode

Applications:

• Weigh Scales

• Direct Temperature Measurement

• 6-digit DVMs

• Instrumentation

• Data Acquisition

• Strain Gauge Measurement

Description:

The Microchip Technology Inc. MCP3550/1/3 devices
are 2.7V to 5.5V low-power, 22-bit Delta-Sigma
Analog-to-Digital Converters ADCs). The devices offer
output noise as low as 2.5 µV
unadjusted error of 10 ppm. The family exhibits 6 ppm
Integral Non-Linearity (INL) error, 3 µV offset error and
less than 2 ppm full scale error. The MCP3550/1/3
devices provide high accuracy and low noise
performance for applications where sensor
measurements (such as pressure, temperature and
humidity) are performed. With the internal oscillator
and high oversampling rate, minimal external
components are required for high-accuracy
applications.

This product line has fully differential analog inputs,
making it compatible with a wide variety of sensor,
industrial control or process control applications.

The MCP3550/1/3 devices operate from -40°C to
+125°C and are available in the space-saving 8-pin
MSOP and SOIC packages.

, with a total

RMS

Package Types

Block Diagram

 2005-2014 Microchip Technology Inc. DS20001950F-page 1

MCP3550/1/3

NOTES:

DS20001950F-page 2  2005-2014 Microchip Technology Inc.

MCP3550/1/3

1.0 ELECTRICAL

CHARACTERISTICS

† Notice: Stresses above those listed under "Absolute

Maximum Ratings" 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 indi-

Absolute Maximum Ratings †

cated in the operation listings of this specification is not
implied. Exposure to maximum rating conditions for extended

VDD...................................................................................7.0V

All inputs and outputs w.r.t V

Difference Input Voltage ....................................... |V

.... .......... -0.3V to VDD+ 0.3V

SS

DD

- VSS|

periods may affect device reliability.

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 (HBM, MM)  6kV, 400V

Maximum Junction Temperature (T

)..........................+150°C

J

DC CHARACTERISTICS

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C  T

V

= 2.5V. VIN+ = VIN- = VCM = V

REF

/2. All ppm units use 2*V

REF

as full scale range. Unless otherwise noted, specification

REF

applies to entire MCP3550/1/3 family.

Parameters Sym. Min. Typ. Max. Units Conditions

Noise Performance (MCP3550/1)

No Missing Codes NMC 22 — — bits At DC (Note 5)

Output Noise e

N

—2.5— µV

Effective Resolution ER — 21.9 — bits RMS V

Noise Performance (MCP3553)

No Missing Codes NMC 20 — — bits At DC (Note 5)

Output Noise e

N

—6—µV

Effective Resolution ER — 20.6 — bits RMS V

Conversion Times

MCP3550-50 t

MCP3550-60 t

MCP3551 t

MCP3553 t

CONV

CONV

CONV

CONV

-2.0% 80 +2.0% ms

-2.0% 66.67 +2.0% ms

-2.0% 73.1 +2.0% ms

-2.0% 16.67 +2.0% ms

Accuracy

Integral Non-Linearity INL — ±2 6 ppm T

Offset Error V

OS

-12 ±3 +12 µV TA = +25°C

—±4— µVT

—±6— µVT

Positive Full-Scale Error V

Negative Full-Scale Error V

FS,P

FS,N

-10 ±2 +10 ppm TA = +25°C only

-10 ±2 +10 ppm TA = +25°C only

Offset Drift — 0.040 — ppm/°C

Positive/Negative Full-Scale Error

— 0.028 — ppm/°C

Drift

Note 1: This parameter is established by characterization and not 100% tested.

2: INL is the difference between the endpoint’s line and the measured code at the center of the quantization band.
3: This current is due to the leakage current and the current due to the offset voltage between V
4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. V
5: Characterized by design, but not tested.
6: Rejection performance depends on internal oscillator accuracy; see Section 4.0 “Device Overview” for more informa-

tion on oscillator and digital filter design. MCP3550/1 device rejection specifications characterized from 49 to 61 Hz.

 +85°C, VDD = 2.7V or 5.0V.

A

RMS

= 5V

REF

RMS

= 5V

REF

= +25°C only (Note 2)

A

= +85°C

A

= +125°C

A

+ and VIN-.

IN

REF

=5V.

 2005-2014 Microchip Technology Inc. DS20001950F-page 3

MCP3550/1/3

DC CHARACTERISTICS (CONTINUED)

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C  T

= 2.5V. VIN+ = VIN- = VCM = V

V

REF

/2. All ppm units use 2*V

REF

as full scale range. Unless otherwise noted, specification

REF

applies to entire MCP3550/1/3 family.

Parameters Sym. Min. Typ. Max. Units Conditions

Rejection Performance

(1,6)

Common Mode DC Rejection — -135 — dB VCM range from 0 to V

Power Supply DC Rejection — -115 — dB

Common Mode 50/60 Hz Rejection CMRR — -135 — dB V
Power Supply 50/60 Hz Rejection PSRR — -85 — dB MCP3551 only, V

Power Supply 50/60 Hz Rejection PSRR — -120 — dB MCP3550-50 or MCP3550-60 only

Normal Mode 50 and 60 Hz

NMRR — -85 — dB MCP3551 only,

Rejection

Normal Mode 50 or 60 Hz

NMRR — -120 — dB MCP3550-50 or MCP3550-60 only

Rejection

Analog Inputs

Differential Input Range V

IN+

V

Absolute/Common Mode Voltages V

IN-

-V

REF

- 0.3 — V

SS

—+V

REF

+ 0.3 V

DD

Analog Input Sampling Capacitor — 10 — pF Note 5

Differential Input Impedance — 2.4 — MΩ

Shutdown Mode Leakage Current — 1 — nA V

Reference Input

Voltage Range 0.1 — V

Reference Input Sampling

—15— pFNote 5

V

DD

Capacitor
Reference Input Impedance — 2.4 — MΩ Note 4

Shutdown Mode Reference

—1— nAV

Leakage Current

Power Requirements

Power Supply Voltage Range V
MCP3550-50, MCP3551 Supply

Current
MCP3550-60, MCP3553 Supply

Current

Supply Current, Sleep Mode I

Supply Current, Shutdown Mode I

DD

I

DD

I

DD

DDSL

DDS

2.7 — 5.5 V

— 120 170 µA VDD = 5V

— 100 — µA V

— 140 185 µA VDD = 5V

— 120 — µA V

—10 µA

—— 1 µACS = SCK = V

Serial Interface

Voltage Input High (CS

Voltage Input Low (CS

Voltage Output High (SDO/RDY

, SCK) V

, SCK) V

)VOHV

IH

IL

0.7 V

——0.4 V

- 0.5 — — V VOH = 1 mA, VDD = 5.0V

DD

—— V

DD

Note 1: This parameter is established by characterization and not 100% tested.

2: INL is the difference between the endpoint’s line and the measured code at the center of the quantization band.
3: This current is due to the leakage current and the current due to the offset voltage between V
4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. V
5: Characterized by design, but not tested.
6: Rejection performance depends on internal oscillator accuracy; see Section 4.0 “Device Overview” for more informa-

tion on oscillator and digital filter design. MCP3550/1 device rejection specifications characterized from 49 to 61 Hz.

 +85°C, VDD = 2.7V or 5.0V.

A

varies from 0V to V

CM

4.5V to 5.5V

DD

at 50 or 60 Hz respectively, V
varies from 4.5V to 5.5V

< VDD,

0 < V

CM

< V

-V

REF

IN

= (V

IN

at 50 or 60 Hz respectively,

< VDD,

0 < V

CM

-V

< V

IN

= (V

IN

REF

V

+ = VIN- = VDD; CS = V

IN

(Note 3)

+ = VIN- = VSS; CS = V

IN

= 2.7V

DD

= 2.7V

DD

DD

+ and VIN-.

IN

DD

DD

varies from

+ -VIN-) < +V

+ -VIN-) < +V

DD

DD

=5V.

REF

DD

REF

REF

DS20001950F-page 4  2005-2014 Microchip Technology Inc.

MCP3550/1/3

DC CHARACTERISTICS (CONTINUED)

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C  T

= 2.5V. VIN+ = VIN- = VCM = V

V

REF

applies to entire MCP3550/1/3 family.

Parameters Sym. Min. Typ. Max. Units Conditions

Voltage Output Low (SDO/RDY)VOL——0.4 VVOH = -1 mA, VDD = 5.0V

Input leakage Current

, SCK)

(CS

Internal Pin Capacitance

, SCK, SDO/RDY)

(CS

Note 1: This parameter is established by characterization and not 100% tested.

2: INL is the difference between the endpoint’s line and the measured code at the center of the quantization band.
3: This current is due to the leakage current and the current due to the offset voltage between V
4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. V
5: Characterized by design, but not tested.
6: Rejection performance depends on internal oscillator accuracy; see Section 4.0 “Device Overview” for more informa-

tion on oscillator and digital filter design. MCP3550/1 device rejection specifications characterized from 49 to 61 Hz.

/2. All ppm units use 2*V

REF

I

LI

C

INT

-1 — 1 µA

—5— pFNote 1

as full scale range. Unless otherwise noted, specification

REF

TEMPERATURE CHARACTERISTICS

Electrical Specifications: Unless otherwise indicated

Parameters Sym. Min. Typ. Max. Units Conditions

Temperature Ranges

Specified Temperature Range T

Operating Temperature Range T

Thermal Package Resistances

Thermal Resistance, 8L-MSOP 

Thermal Resistance, 8L-SOIC 

A

A

JA

JA

-40 — +85 °C

-40 — +125 °C

—211—°C/W

—149.5—°C/W

 +85°C, VDD = 2.7V or 5.0V.

A

+ and VIN-.

IN

REF

=5V.

SERIAL TIMINGS

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C  T

= 3.3V or 5.0V, SDO load = 50 pF.

V

DD

Parameters Sym. Min. Typ. Max. Units Conditions

CLK Frequency f

CLK High t

CLK Low t

CLK fall to output data valid t

low to indicate RDY state t

CS

minimum low time t

CS

flag setup time t

RDY

rise to output disable t

CS

disable time t

CS

Power-up to CS

High to Shutdown Mode t

CS

Note: This parameter is established by characterization and not 100% tested.

LOW t

SCK

HI

LO

DO

RDY

CSL

SU

DIS

CSD

PUCSL

CSHSD

—— 5MHz

90 — — ns

90 — — ns

0 — 90 ns

0 — 50 ns

8——µsNote

20 — — ns

20 — — ns

90 — — ns

—10—µs

—10—µs

 +85°C,

A

 2005-2014 Microchip Technology Inc. DS20001950F-page 5

MCP3550/1/3

t

RDY

t

CSL

t

DO

t

SU

f

SCK

t

HItLO

t

DIS

CS

SDO

SCK

t

CSD

t

CSHSD

/RDY

V

DD

CS

t

PUCSL

FIGURE 1-1: Serial Timing.

FIGURE 1-2: Power-Up Timing.

DS20001950F-page 6  2005-2014 Microchip Technology Inc.

MCP3550/1/3

-5

-4

-3

-2

-1

0

1

2

3

4

5

-2.5 -1.5 -0.5 0.5 1.5 2.5
V

IN

(V)

INL (ppm)

+125 C

+85 C

-40 C

+25 C

-5

-4

-3

-2

-1

0

1

2

3

4

5

-2.5 -1.5 -0.5 0.5 1.5 2.5
V

IN

(V)

INL (ppm )

+125 C

+85 C

+25 C

- 40 C

-10

-8

-6

-4

-2

0

2

4

6

8

10

-5 -4 -3 -2 -1 0 1 2 3 4 5
V

IN

(V)

INL (ppm )

+125 C
+85 C

+25 C

-40 C

0

2

4

6

8

10

00.511.522.533.544.55
V

REF

(V)

INL Error (ppm)

0

1

2

3

4

5

6

7

8

9

10

-50 -25 0 25 50 75 100 125
Temperature (°C)

Max INL (ppm)

0

1

2

3

4

5

6

7

8

9

10

-2.5 -1.5 -0.5 0.5 1.5 2.5

V

IN

(Vo l ts)

Output Noise (µV

RMS

)

MCP3553

MCP3550/1

2.0 TYPICAL PERFORMANCE CURVES

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.

Note: Unless otherwise specified, T

All ppm units use 2*V

as full scale range. Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

REF

= +25°C, VDD = 5V, V

A

FIGURE 2-1: INL Error vs. Input Voltage
(V

= 2.7V).

DD

= 2.5V, VSS = 0V, VCM = V

REF

/2, VIN+ = VIN-.

REF

FIGURE 2-4: Maximum INL Error vs.
V

.

REF

FIGURE 2-2: INL Error vs. Input Voltage

= 5.0V).

(V

DD

FIGURE 2-3: INL Error vs. Input Voltage
(V

DD

= 5.0V, V

REF

= 5V).

 2005-2014 Microchip Technology Inc. DS20001950F-page 7

FIGURE 2-5: Maximum INL Error vs. Temperature.

FIGURE 2-6: Output Noise vs. Input
Voltage (V

= 2.7V).

DD

MCP3550/1/3

0

5

10

15

-2.5 -1.5 -0.5 0.5 1.5 2.5
V

IN

(V)

Output Noise (µV

RMS

)

MCP3553

MCP3550/1

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

0.01.02.03.04.05.0

V

REF

(V)

Output Noise (µV

RMS

)

0

1

2

3

4

5

6

7

8

9

10

2.5 3 3.5 4 4.5 5 5.5
V

DD

(V)

Output Noise (µV

RMS

)

0

1

2

3

4

5

6

7

8

9

10

-50-250 255075100125
Temperature (°C)

Output Noise (µV

RMS

)

MCP3550/1

MCP3553

0

1

2

3

4

5

2.533.544.555.5
V

DD

(V)

Offset (µV)

0

1

2

3

4

5

6

7

-50 -25 0 25 50 75 100 125

Temperature (°C)

Offset (µV)

Note: Unless otherwise specified, T

All ppm units use 2*V

as full scale range. Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

REF

= +25°C, VDD = 5V, V

A

FIGURE 2-7: Output Noise vs. Input
Voltage (V

u

= 5.0V).

DD

MCP3553

MCP3550/1

= 2.5V, VSS = 0V, VCM = V

REF

/2, VIN+ = VIN-.

REF

FIGURE 2-10: Output Noise vs. Temperature.

FIGURE 2-8: Output Noise vs. V

MCP3553

MCP3550/1

FIGURE 2-9: Output Noise vs.V

DS20001950F-page 8  2005-2014 Microchip Technology Inc.

REF

DD

.

.

FIGURE 2-11: Offset Error vs V
(V

=0V).

CM

FIGURE 2-12: Offset Error vs.
Temperature (V

REF

= 5.0V).

DD

MCP3550/1/3

-5

-4

-3

-2

-1

0

1

2

3

4

5

2.533.544.555.5
V

DD

(V)

Full Scale Error (ppm)

Posit ive Full Scal e

Negative Full Scale

-10

-8

-6

-4

-2

0

2

4

6

8

10

-50 -25 0 25 50 75 100 125
Temperature (°C)

Full Scale Error (ppm)

Positive Full Scale

Negative Full Scale

-10

-8

-6

-4

-2

0

2

4

6

8

10

-50 -25 0 2 5 50 75 100 125
Temperature (°C)

Full Scale Error (ppm)

Posi tive Full Sca le

Negative Full Scale

0

500

1000

1500

2000

2500

3000

3500

4000

VDD= 5V
V

REF

= 2.5V

V

CM

= 1.25V

V

IN

= 0V

T

A

= 25C
16384
consecutive
readings

0

200

400

600

800

1000

1200

1400

1600

1800

-15 -10 -5 0 5 10 15
Output Code (LSB)

Number of O cc ur r ences

V

DD

= 5V

V

REF

= 2.5V

V

CM

= 1.25V

V

IN

= 0V

T

A

= 25°C
16384
consecutive

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

-2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5
V

IN

(V)

TUE (ppm)

Note: Unless otherwise specified, T

All ppm units are ratioed against 2*V

= +25°C, VDD = 5V, V

A

Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

REF .

FIGURE 2-13: Full Scale Error vs. VDD.

= 2.5V, VSS = 0V, VCM = V

REF

/2, VIN+ = VIN-.

REF

Number of Occurrences

-15 -10 -5 0 5 10 15

Output Code (LSB)

FIGURE 2-16: MCP3550/1 Output Noise Histogram.

readings

FIGURE 2-14: Full Scale Error vs. Temperature.

FIGURE 2-15: Full Scale Error vs.
Temperature (V

 2005-2014 Microchip Technology Inc. DS20001950F-page 9

REF

= 5.0V).

FIGURE 2-17: MCP3553 Output Noise Histogram.

FIGURE 2-18: Total Unadjusted Error
(TUE) vs. Input Voltage (V

= 2.7V).

DD

MCP3550/1/3

-5

-4

-3

-2

-1

0

1

2

3

4

5

-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5
V

IN

(V)

TUE (ppm)

-10

-8

-6

-4

-2

0

2

4

6

8

10

-5 -4 -3 -2 -1 0 1 2 3 4 5
V

IN

(V)

TUE (ppm)

0

1

2

3

4

5

6

7

8

9

10

012345

V

REF

(V)

Maximum TUE (ppm)

0

1

2

3

4

5

6

-50 -25 0 25 50 75 100 125
Temperature (°C)

Maximum TUE (ppm)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

2.52.733.34 55.5
V

DD

(V)

TUE (ppm)

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

-50 -25 0 25 50 75 100 125

Temp erature (°C)

I

DDS

(µA)

MCP3550/1

MCP3553

Note: Unless otherwise specified, T

All ppm units use 2*V

as full scale range.

REF

= +25°C, VDD = 5V, V

A

FIGURE 2-19: Total Unadjusted Error (TUE) vs. Input Voltage.

= 2.5V, VSS = 0V, VCM = V

Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

REF

/2, VIN+ = VIN-.

REF

FIGURE 2-22: Maximum TUE vs. Temperature.

FIGURE 2-20: Total Unadjusted Error
(TUE) vs. Input Voltage (V

REF

FIGURE 2-21: Maximum TUE vs. V

DS20001950F-page 10  2005-2014 Microchip Technology Inc.

= 5.0V).

REF

FIGURE 2-23: Maximum TUE vs. V

.

FIGURE 2-24: I

vs. Temperature.

DDS

DD

.

MCP3550/1/3

0

20

40

60

80

100

120

140

160

180

200

2.5 3 3.5 4 4.5 5 5.5
V

DD

(V)

I

DD

(µA)

MCP3 550-60, MC P 3 553

MCP355 0-50, MCP 3550/1

0

20

40

60

80

100

120

140

160

-50-250 255075100125
Temper ature (°C )

I

DD

(µA)

MCP355 0-60, MCP3553

MCP3550-50, MCP3550/1

Note: Unless otherwise specified, T

All ppm units use 2*V

as full scale range. Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

REF

= +25°C, VDD = 5V, V

A

= 2.5V, VSS = 0V, VCM = V

REF

/2, VIN+ = VIN-.

REF

FIGURE 2-25: IDD vs. VDD. FIGURE 2-26: IDD vs. Temperature.

 2005-2014 Microchip Technology Inc. DS20001950F-page 11

MCP3550/1/3

NOTES:

DS20001950F-page 12  2005-2014 Microchip Technology Inc.

3.0 PIN DESCRIPTIONS

The descriptions of the pins are listed in Tabl e 3 - 1.

TABLE 3-1: PIN FUNCTION TABLE

MCP3550/1/3

MCP3550/1/3

MSOP, SOIC

1V

2V

3V

4V

5 SCK I Serial Clock Digital Input pin

6 SDO/RDY

7CS

8V

Type Identification: I = Input; O = Output; P = Power

3.1 Voltage Reference (V

The MCP3550/1/3 devices accept single-ended
reference voltages from 0.1V to V
converter output noise is dominated by thermal noise,
which is independent of the reference voltage, the
output noise is not significantly improved by
diminishing the reference voltage at the V
A reduced voltage reference will significantly improve
the INL performance (see Figure 2-4); the INL max
error is proportional to V

Symbol I/O/P Description

REF

+ I Non-inverting Analog Input pin

IN

- I Inverting Analog Input pin

IN

SS

DD

)

REF

DD

2

.

REF

I Reference Voltage Analog Input pin

P Ground pin

O Data/Ready Digital Output pin

I Chip Select Digital Input pin

P Positive Supply Voltage pin

. Since the

input pin.

REF

3.2 Analog Inputs (VIN+, VIN-)

The MCP3550/1/3 devices accept a fully differential
analog input voltage to be connected on the V
V

- input pins. The differential voltage that is

IN

converted is defined by V
differential voltage range specified for ensured
accuracy is from -V
converter will still output valid and usable codes with

the inputs overranged by up to 12% (see Section 5.0

“Serial Interface”) at room temperature. This

overrange is clearly specified by two overload bits in
the output code.

The absolute voltage range on these input pins extends
from V
below this range will create leakage currents through
the Electrostatic Discharge (ESD) diodes. This current
will increase exponentially, degrading the accuracy and
noise performance of the device. The common mode of
the analog inputs should be chosen such that both the
differential analog input range and the absolute voltage
range on each pin are within the specified operating

range defined in Section 1.0 “Electrical

Characteristics”.

– 0.3V to VDD + 0.3V. Any voltage above or

SS

REF

= VIN+ – VIN-. The

IN

to +V

. However, the

REF

IN

+ and

3.3 Supply Voltage (VDD, VSS)

VDD is the power supply pin for the analog and digital
circuitry within the MCP3550/1/3. This pin requires an
appropriate bypass capacitor of 0.1 µF. The voltage on
this pin should be maintained in the 2.7V to 5.5V range
for specified operation. VSS is the ground pin and the
current return path for both analog and digital circuitry
of the MCP3550/1/3. If an analog ground plane is
available, it is recommended that this device be tied to
the analog ground plane of the Printed Circuit Board
(PCB).

3.4 Serial Clock (SCK)

SCK synchronizes data communication with the
device. The device operates in both SPI mode 1,1 and
SPI mode 0,0. Data is shifted out of the device on the
falling edge of SCK. Data is latched in on the rising
edge of SCK. During CS
idle either high or low.

high times, the SCK pin can

3.5 Data Output (SDO/RDY)

SDO/RDY is the output data pin for the device. Once a
conversion is complete, this pin will go active-low,
acting as a ready flag. Subsequent falling clock edges
will then place the 24-bit data word (two overflow bits

and 22 bits of data, see Section 5.0 “Serial

Interface”) on the SPI bus through the SDO pin. Data

is clocked out on the falling edge of SCK.

 2005-2014 Microchip Technology Inc. DS20001950F-page 13

MCP3550/1/3

3.6 Chip Select (CS)

CS gates all communication to the device and can be
used to select multiple devices that share the same
SCK and SDO/RDY
control the internal conversions, which begin on the
falling edge of CS. Raising CS before the first internal
conversion is complete places the device in Single
Conversion mode. Leaving CS low will place the
device in Continuous Conversion mode (i.e., additional
internal conversions will automatically occur). CS
be tied permanently low for two-wire Continuous
Conversion mode operation. SDO/RDY enters a high­impedance state with CS

pins. This pin is also used to

may

high.

DS20001950F-page 14  2005-2014 Microchip Technology Inc.

MCP3550/1/3

Internal

Oscillator

Third-Order

∆Σ

Modulator

Digital

Decimation

Filter (SINC

4

)

SPI 3-wire

Interface

Gain and

Offset

Calibration

Differential

Analog Input

Bit

Conversion

Code

Output

Code

Clock

Charge

Transfer

Reference

Input

Stream

4.0 DEVICE OVERVIEW

The MCP3550/1/3 devices are 22-bit delta-sigma
ADCs that include fully differential analog inputs, a
third-order delta-sigma modulator, a fourth-order
modified SINC decimation filter, an on-chip, low-noise
internal oscillator, a power supply monitoring circuit and
an SPI 3-wire digital interface. These devices can be
easily used to measure low-frequency, low-level
signals such as those found in pressure transducers,
temperature, strain gauge, industrial control or process
control applications. The power supply range for this
product family is 2.7V to 5.5V; the temperature range is

-40°C to +125°C. The functional block diagram for the
MCP3550/1/3 devices is shown in Figure 4-1.

A Power-On Reset (POR) monitoring circuit is included
to ensure proper power supply voltages during the
conversion process. The clock source for the part is
internally generated to ±0.5% over the full-power
supply voltage range and industrial temperature range.
This stable clock source allows for superior conversion
repeatability and minimal drift across conversions.

The MCP3550/1/3 devices employ a delta-sigma
conversion technique to realize up to 22 bits of no
missing code performance with 21.9 Effective Number
of Bits (ENOB). These devices provide single-cycle
conversions with no digital filter settling time. Every
conversion includes an internal offset and gain auto­calibration to reduce device error. These calibrations
are transparent to the user and are done in real-time
during the conversion. Therefore, these devices do not
require any additional time or conversion to proceed,
allowing easy usage of the devices for multiplexed
applications. The MCP3550/1/3 devices incorporate a
fourth-order digital decimation filter in order to allow
superior averaging performance, as well as excellent
line frequency rejection capabilities. The oversampling
frequency also reduces any external anti-aliasing filter
requirements.

The MCP3550/1/3 devices communicate with a simple
3-wire SPI interface. The interface controls the
conversion start event, with an added feature of an
auto-conversion at system power-up by tying the CS
pin to logic-low. The device can communicate with bus
speeds of up to 5 MHz, with 50 pF capacitive loading.
The interface offers two conversion modes: Single
Conversion mode for multiplexed applications and a
Continuous Conversion mode for multiple conversions
in series. Every conversion is independent of each
other. That is, all internal registers are flushed between
conversions. When the device is not converting, it auto­matically goes into Shutdown mode and, while in this
mode, consumes less than 1 µA.

FIGURE 4-1: MCP3550/1/3 Functional Block Diagram.

 2005-2014 Microchip Technology Inc. DS20001950F-page 15

MCP3550/1/3

4.1 MCP3550/1/3 Delta-Sigma
Modulator with Internal Offset and
Gain Calibration

The converter core of the MCP3550/1/3 devices is a
third-order delta-sigma modulator with automatic gain
and offset error calibrations. The modulator uses a 1-bit
DAC structure. The delta-sigma modulator processes
the sampled charges through switched capacitor
structures controlled by a very low drift oscillator for
reduced clock jitter.

During the conversion process, the modulator outputs
a bit stream with the bit frequency equivalent to the

/4 (see Tab l e 4 - 1). The high oversampling

f

OSC

implemented in the modulator ensures very high
resolution and high averaging factor to achieve low­noise specifications. The bit stream output of the
modulator is then processed by the digital decimation
filter in order to provide a 22-bit output code at a data
rate of 12.5 Hz for the MCP3550-50, 15 Hz for the
MCP3550-60, 13.75 Hz for the MCP3551 and 60 Hz
for the MCP3553. Since the oversampling ratio is lower
with the MCP3553 device, a much higher output data
rate is achieved while still achieving 20 bits No Missing
Codes (NMC) and 20.6 ENOB.

A self-calibration of offset and gain occurs at the onset
of every conversion. The conversion data available at
the output of the device is always calibrated for offset
and gain through this process. This offset and gain
auto-calibration is performed internally and has no
impact on the speed of the converter since the offset
and gain errors are calibrated in real-time during the
conversion. The real-time offset and gain calibration
schemes do not affect the conversion process.

4.2 Digital Filter

The MCP3550/1/3 devices include a digital decimation
filter, which is a fourth-order modified SINC filter. This
filter averages the incoming bit stream from the
modulator and outputs a 22-bit conversion word in
binary two's complement. When all bits have been
processed by the filter, the output code is ready for SPI
communication, the RDY
pin and all the internal registers are reset in order to
process the next conversion.

Like the commonly used SINC filter, the modified SINC
filter in the MCP3550/1/3 family has the main notch
frequency located at f
stream sample frequency. OSR is the Oversampling
Ratio and L is the order of the filter.

The MCP3550-50 device has the main filter notch
located at 50 Hz. For the MCP3550-60 device, the
notch is located at 60 Hz. The MCP3551 device has its
notch located at 55 Hz, and for the MCP3553 device,
the main notch is located at 240 Hz, with an OSR of

128. (see Table 4-1 for rejection performance).

The digital decimation SINC filter has been modified in
order to offer staggered zeros in its transfer function.
This modification is intended to widen the main notch in
order to be less sensitive to oscillator deviation or line­frequency drift. The MCP3551 filter has staggered
zeros spread in order to reject both 50 Hz and 60 Hz
line frequencies simultaneously (see Figure 4-2).

flag is set on the SDO/RDY

/(OSR*L), where fS is the bit

S

T ABLE 4-1: DATA RATE, OUTPUT NOISE AND DIGITAL FILTER SPECIFICATIONS BY DEVICE

Output Data

Device

MCP3550-50 80.00 ms 2.5 50 25600 Hz 102.4 kHz -120 dB min. at

MCP3550-60 66.67 ms 2.5 60 30720 Hz 122.88 kHz -120 dB min. at

MCP3551 72.73 ms 2.5 55 28160 Hz 112.64 kHz -82 dB min. from

MCP3553 16.67 ms 6 240 30720 Hz 122.88 kHz Not Applicable

Note: For the first conversion after exiting Shutdown, t

the conversion is complete and the RDY

DS20001950F-page 16  2005-2014 Microchip Technology Inc.

Rate (t

(Note)

CONV

)

Output

Noise

(µV

Primary

Notch

)

RMS

(Ready) flag appears on SDO/RDY.

(Hz)

CONV

Sample

Frequency

(fS)

must include an additional 144 f

Internal

Clock

f

OSC

50/60 Hz Rejection

50 Hz

60 Hz

48 Hz to 63 Hz. -

82 dB at 50 Hz and

-88 dB at 60 Hz

periods before

OSC

MCP3550/1/3

-120

-100

-80

-60

-40

-20

0

050100150200

Frequency (Hz)

Attenuation (dB)

-120

-100

-80

-60

-40

-20

0

0 60 120 180 240

Frequency (Hz)

Attenuat ion (dB)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

0 102030405060708090100110

Frequency (Hz)

Attenuation (dB)

-140

-120

-100

-80

-60

-40

-20

0

0 28160 56320 84480 112640 140800 168960 197120 225280 253440

Frequency (Hz)

Normal Mode Rejection (dB)

:

FIGURE 4-2: SINC Filter Response, MCP3550-50 Device.

:

FIGURE 4-3: SINC Filter Response, MCP3550-60 Device.

:

FIGURE 4-4: SINC Filter Response, MCP3551 Device, Simultaneous 50/60 Hz Rejection.

FIGURE 4-5: SINC Filter Response at
Integer Multiples of the Sampling Frequency (f

s

4.3 Internal Oscillator

The MCP3550/1/3 devices include a highly stable and
accurate internal oscillator that provides clock signals
to the delta-sigma ADC with minimum jitter. The
oscillator is a specialized structure with a low
temperature coefficient across the full range of
specified operation. See Tab le 4- 1 for oscillator
frequencies.

The conversion time is an integer multiple of the
internal clock period and, therefore, has the same
accuracy as the internal clock frequency. The internal
oscillator frequency is 102.4 kHz ±1% for the
MCP3550-50, 112.64 kHz ±1% for the MCP3551, and

122.88 kHz ±1% for the MCP3550-60 and MCP3553
devices, across the full power supply voltage and
specified temperature ranges.

The notch of the digital filter is proportional to the
internal oscillator frequency, with the exact notch
frequency equivalent to the oscillator accuracy
(< 1% deviation). This high accuracy, combined with
wide notches, will ensure that the MCP3551 will have
simultaneous 50 Hz and 60 Hz line frequency rejection
and the MCP3550-50 or MCP3550-60 devices will
have greater than 120 dB rejection (at either 50 or
60 Hz) by the digital filtering, even when jitter is
present.

The internal oscillator is held in the reset condition
when the part is in Shutdown mode to ensure very low
power consumption (< 1 µA in Shutdown mode). The
internal oscillator is independent of all serial digital
interface edges (i.e., state machine processing the
digital SPI interface is asynchronous with respect to the
internal clock edges).

).

 2005-2014 Microchip Technology Inc. DS20001950F-page 17

MCP3550/1/3

4.4 Differential Analog Inpu ts

The MCP3550/1/3 devices accept a fully differential
analog input voltage to be connected to the V

input pins. The differential voltage that is converted

V

IN-

is defined by V

= VIN+ – VIN-. The differential voltage

IN

range specified for ensured accuracy is from -V

.

+V

REF

The converter will output valid and usable codes from

-112% to 112% of output range (see Section 5.0

“Serial Interface”) at room temperature. The ±12%

overrange is clearly specified by two overload bits in
the output code: OVH and OVL. This feature allows for
system calibration of a positive gain error.

The absolute voltage range on these input pins extends
from V

- 0.3V to V

SS

+ 0.3V. If the input voltages are

DD

above or below this range, the leakage currents of the
ESD diodes will increase exponentially, degrading the
accuracy and noise performance of the converter. The
common mode of the analog inputs should be chosen
such that both the differential analog input range and
absolute voltage range on each pin are within the

specified operating range defined in Section 1.0

“Electrical Characteri stics”.

Both the analog differential inputs and the reference
input have switched-capacitor input structures. The
input capacitors are charged and discharged
alternatively with the input and the reference in order to
process a conversion. The charge and discharge of the
input capacitors create dynamic input currents at the

+ and VIN- input pins inversely proportional to the

V

IN

sampling capacitor. This current is a function of the
differential input voltages and their respective common
modes. The typical value of the differential input
impedance is 2.4 MΩ, with V

= 2.5V, V

CM

DD

5V. The DC leakage current caused by the ESD input
diodes, even though on the order of 1 nA, can cause
additional offset errors proportional to the source
resistance at the V

+ and VIN- input pins.

IN

From a transient response standpoint and as a first­order approximation, these input structures form a
simple RC filtering circuit with the source impedance in
series with the R

(switched resistance when closed)

ON

of the input switch and the sampling capacitor. In order
to ensure the accuracy of the sampled charge, proper
settling time of the input circuit has to be considered.
Slow settling of the input circuit will create additional
gain error. As a rule of thumb, in order to obtain 1 ppm
absolute measurement accuracy, the sampling period
must be 14 times greater than the input circuit RC time
constant.

IN+

= V

REF

REF

and

to

4.5 Voltage Reference Input Pin

The MCP3550/1/3 devices accept a single-ended
external reference voltage, to be connected on the

input pin. Internally, the reference voltage for the

V

REF

ADC is a differential voltage with the non-inverting input
connected to the V
connected to the V
voltage is V

REF - VSS

reference is always (V

pin and the inverting input

REF

pin. The value of the reference

SS

and the common mode of the

- VSS)/2.

REF

The MCP3550/1/3 devices accept a single-ended
reference voltage from 0.1V to V

The converter

DD.

output noise is dominated by thermal noise that is
independent of the reference voltage. Therefore, the
output noise is not significantly improved by lowering
the reference voltage at the V

input pin. However, a

REF

reduced reference voltage will significantly improve the
INL performance since the INL max error is
proportional to V

2

(see Figure 2-4).

REF

The charge and discharge of the input capacitor create
dynamic input currents at the V

input pin inversely

REF

proportional to the sampling capacitor, which is a func­tion of the input reference voltage. The typical value of
the single-ended input impedance is 2.4 MΩ, with
V

DD=VREF

= 5V. The DC leakage current caused by
the ESD input diodes, though on the order of 1 nA
typically, can cause additional gain error proportional to
the source resistance at the V

REF

pin.

4.6 Power-On Reset (POR)

The MCP3550/1/3 devices contain an internal Power­On Reset (POR) circuit that monitors power supply
voltage VDD during operation. This circuit ensures

=

correct device start-up at system power-up and power­down events. The POR has built-in hysteresis and a
timer to give a high degree of immunity to potential
ripple and noise on the power supplies, as well as to
allow proper settling of the power supply during power­up. A 0.1 µF decoupling capacitor should be mounted
as close as possible to the V

pin, providing additional

DD

transient immunity.

The threshold voltage is set at 2.2V, with a tolerance of
approximately ±5%. If the supply voltage falls below
this threshold, the MCP3550/1/3 devices will be held in
a reset condition or in Shutdown mode. When the part
is in Shutdown mode, the power consumption is less
than 1 µA. The typical hysteresis value is around
200 mV in order to prevent reset during brown-out or
other glitches on the power supply.

DS20001950F-page 18  2005-2014 Microchip Technology Inc.

MCP3550/1/3

V

DD

2.2V

2.0V

0V

Reset

Normal

Operation

ResetStart-up

Time

300 µs

Once a power-up event has occurred, the device must
require additional time before a conversion can take
place. During this time, all internal analog circuitry must
settle before the first conversion can occur. An internal
timer counts 32 internal clock periods before the
internal oscillator can provide clock to the conversion
process. This allows all internal analog circuitry to
settle to their proper operating point. This timing is
typically less than 300 µs, which is negligible compared
to one conversion time (e.g. 72.7 ms for the
MCP3551). Figure 4-6 illustrates the conditions for a
power-up and power-down event under typical start-up
conditions.

4.8 Sleep Mode

During Sleep mode, the device is not converting and is
awaiting data retrieval; the internal analog circuitry is
still running and the device typically consumes 10 µA.
In order to restart a conversion while in Sleep mode,
toggling CS
down mode) and then back to a logic-low will restart the
conversion. Sleep can only be entered in Single
Conversion mode. Once a conversion is complete in
Single Conversion mode, the device automatically
enters Sleep mode.

to a logic-high (placing the part in Shut-

FIGURE 4-6: Power-On Reset Operation.

4.7 Shutdown Mode

When not internally converting, the two modes of
operation for the MCP3550/1/3 devices are
Shutdown and Sleep modes. During Shutdown mode,
all internal analog circuitry, including the POR, is turned
off and the device consumes less than 1 µA. When
exiting Shutdown mode, the device must require
additional time before a conversion can take place.
During this time, all internal analog circuitry must settle
before the first conversion can occur. An internal timer
counts 32 internal clock periods before the internal
oscillator can provide clock to the conversion process.
This allows all internal analog circuitry to settle to their
proper operating point. This timing is typically less than
300 µs, which is negligible compared to one conversion
time (72.7 ms for MCP3551).

the

 2005-2014 Microchip Technology Inc. DS20001950F-page 19

MCP3550/1/3

NOTES:

DS20001950F-page 20  2005-2014 Microchip Technology Inc.

MCP3550/1/3

CS

SCK

DOO

21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 321

0

READY

H

L

R

High Z

SDO/RDY

5.0 SERIAL INTERFACE

5.1 Overview

Serial communication between the microcontroller and
the MCP3550/1/3 devices is achieved using CS
and SDO/RDY

. There are two modes of operation:
Single Conversion and Continuous Conversion. CS
controls the conversion start. There are 24 bits in the
data word: 22 bits of conversion data and two overflow
bits. The conversion process takes place via the
internal oscillator and the status of this conversion
must be detected. The typical method of
communication is shown in Figure 5-1. The status of
the internal conversion is the SDO/RDY
available with CS

low. A High state on SDO/RDY
means the device is busy converting, while a Low
state means the conversion is finished and data is
ready for transfer using SCK. SDO/RDY
high-impedance state when CS

is held high. CS must
be low when clocking out the data using SCK and
SDO/RDY.

Bit 22 is Overflow High (OVH) when V

> V

IN

OVH toggles to logic ‘1’, detecting an overflow high in
the analog input voltage.

Bit 23 is Overflow Low (OVL) when V

IN

< -V

toggles to logic ‘1’, detecting an overflow low in the
analog input voltage. The state OVH = OVL = ‘1’ is not
defined and should be considered as an interrupt for
the SPI interface meaning erroneous communication.

, SCK

pin and is

remains in a

– 1 LSB,

REF

, OVL

REF

Bit 21 to bit 0 represents the output code in 22-bit
binary two's complement. Bit 21 is the sign bit and is
logic ‘0’ when the differential analog input is positive
and logic ‘1’ when the differential analog input is
negative. From Bit 20 to bit 0, the output code is given
MSb first (MSb is bit 20 and LSB is Bit 0). When the
analog input value is comprised between -V

– 1 LSB, the two overflow bits are set to logic ‘0’.

V

REF

REF

and

The relationship between input voltage and output
code is shown in Figure 5-1.

The delta-sigma modulator saturation point for the
differential analog input is located at around ±112% of

(at room temperature), meaning that the

V

REF

modulator will still give accurate output codes with an
overrange of 12% below or above the reference
voltage. Unlike the usual 22-bit device, the 22-bit out­put code will not lock at 0x1FFFFF for positive sign
inputs or 0x200000 for negative sign inputs in order to
take advantage of the overrange capabilities of the
device. This can be practical for closed-loop
operations, for instance. In case of an overflow, the
output code becomes a 23-bit two's complement output
code, where the sign bit will be the OVL bit. If an
overflow high or low is detected, OVL (bit 23) becomes
the sign bit (instead of bit 21), the MSb is then bit 21
and the converter can be used as a 23-bit two's
complement code converter, with output code from bits
B21 to B0, and OVL as the sign bit. Figure 5-1
summarizes the output coding data format with or
without overflow high and low.

FIGURE 5-1: Typical Serial Device Communication and Example Digital Output Codes for Specific Analog Input Voltages.

 2005-2014 Microchip Technology Inc. DS20001950F-page 21

MCP3550/1/3

CS

Int. Osc

t

CONV

Sleep

Shutdown

SCK (opt)

SDO/RDY

High Z

High Z

x24

CS

Int. Osc

t

CONV

Shutdown

SCK (opt)

t

CONV

t

CONV

SDO/RDY

High Z

x24

5.2 Controlling Internal Conversions and the Internal Oscillator

During Shutdown mode, on the falling edge of CS, the
conversion process begins. During this process, the
internal oscillator clocks the delta-sigma modulator and
the SINC filter until a conversion is complete. This
conversion time is t

Figure 5-2. At the end of t

settled completely and there is no latency involved with
the digital SINC filter of the MCP3550/1/3.

The two modes of conversion for the MCP3550/1/3
devices are Single Conversion and Continuous
Conversion. In Single Conversion mode, a consecutive
conversion will not automatically begin. Instead, after a
single conversion is complete and the SINC filter have
settled, the device puts the data into the output register
and enters shutdown.

and the timing is shown in

CONV

, the digital filter has

CONV

In Continuous Conversion mode, a consecutive
conversion will be automatic. In this mode, the device
is continuously converting, independent of the serial
interface. The most recent conversion data will always
be available in the Output register.

When the device exits Shutdown, there is an internal
power-up delay that must be observed.

FIGURE 5-2: Single Conversion Mode.

FIGURE 5-3: Continuous Conversion Mode.

DS20001950F-page 22  2005-2014 Microchip Technology Inc.

MCP3550/1/3

t

CONV

CS

Int. Osc

SDO/RDY

High Z

t

CONV

t

CONV

t

CONV

CS

Int. Osc

SCK & SDO/RDY

A

B

C

Conversion B data is clocked

out of the device here.

5.3 Single Conversion Mode

If a rising edge of Chip Select (CS) occurs during t

a subsequent conversion will not take place and the

device will enter low-power Shutdown mode after

completes. This is referred to as Single

t

CONV

Conversion mode. This operation is demonstrated in

Figure 5-2. Note that a falling edge of CS

same conversion that detected a rising edge, as in

Figure 5-2, will not initiate a new conversion. The data

must be read during sleep mode, with CSN low, and will
be lost as soon as the part enters in shutdown mode
(with a rising edge of CSN). After the final data bit has
been clocked out on the 25th clock, the SDO/RDY
will go active-high.

5.3.1 READY FUNCTION OF SDO/RDY
PIN, SINGLE CONVERSION MODE

At every falling edge of CS during the internal
conversion, the state of the internal conversion is
latched on the SDO/RDY
information. A High state means the device is currently
performing an internal conversion and data cannot be
clocked out. A Low state means the device has finished
its conversion and the data is ready for retrieval on the
falling edge of SCK. This operation is demonstrated in

Figure 5-4. Note that the device has been put into

Single Conversion mode with the first rising edge of

.

CS

pin to give ready or busy

CONV

during the

pin

5.4 Continuous Conversion Mode

,

If no rising edge of CS occurs during any given
conversion per Figure 5-3, a subsequent conversion
will take place and the contents of the previous conver­sion will be overwritten. This operation is demonstrated
in Figure 5-5. Once conversion output data has started
to be clocked out, the output buffer is not refreshed until
all 24 bits have been clocked. A complete read must
occur in order to read the next conversion in this mode.
The subsequent conversion data to be read will then be
the most recent conversion. The conversion time is
fixed and cannot be shortened by the rising edge of CS
This rising edge will place the part in Shutdown mode
and all conversion data will be lost.

The transfer of data from the SINC filter to the output
buffer is demonstrated in Figure 5-5. If the previous
conversion data is not clocked out of the device, it will
be lost and replaced by the new conversion. When the
device is in Continuous Conversion mode, the most
recent conversion data is always present at the output
register for data retrieval.

.

Note: The Ready state is latched on each falling

edge of CS and will not dynamically
update if CS

is held low. CS must be

toggled high through low.

FIGURE 5-5: Most Current Continuous Conversion Mode Data.

If a conversion is in process, it cannot be terminated
with the rising edge of CS

. SDO/RDY must first
transition to a Low state, which will indicate the end of
conversion.

FIGURE 5-4: RDY Functionality in Single Conversion Mode.

 2005-2014 Microchip Technology Inc. DS20001950F-page 23

MCP3550/1/3

5.4.1 READY FUNCTION OF SDO/RDY
PIN IN CONTINUOUS CONVERSION
MODE

The device enters Continuous Conversion mode if no
rising edge of CS
consecutive conversions ensue. SDO/RDY
high, indicating that a conversion is in process. When
a conversion is complete, SDO/RDY will change to a
Low state. With the Low state of SDO/RDY
first conversion, the conversion data can be accessed
with the combination of SCK and SDO/RDY. If the data
ready event happens during the clocking out of the
data, the data ready bit will be displayed after the
complete 24-bit word communication (i.e., the data
ready event will not interrupt a data transfer).

If 24 bits of data are required from this conversion, they
must be accessed during this communication. You can
terminate data transition by bringing CS
remaining data will be lost and the converter will go into
Shutdown mode. Once the data has been transmitted
by the converter, the SDO/RDY
LSB state until the 25th falling edge of SCK. At this
point, SDO/RDY is released from the Data Acquisition
mode and changed to the RDY

Note: The RDY

mode; the RDY flag dynamically updates
on the SDO/RDY pin and remains in this
state until data is clocked out using the
SCK pin.

is seen during t

high, but the

pin will remain in the

state.

state is not latched to CS in this

and

CONV

will be

after this

5.4.2 2-WIRE CONTINUOUS
CONVERSION OPERATION,
(CS

TIED PERMANENTLY LOW)

It is possible to use only two wires to communicate with
the MCP3550/1/3 devices. In this state, the device is
always in Continuous Conversion mode, with internal
conversions continuously occurring. This mode can be
entered by having CS
it to a low position after power-up. If CS
up, the first conversion of the converter is initiated
approximately 300 µs after the power supply has
stabilized.

low during power-up or changing

is low at power-

DS20001950F-page 24  2005-2014 Microchip Technology Inc.

MCP3550/1/3

CS

SCK

SDO/RDY

MCU

Data stored into MCU
receive register after
transmission of first byte

Receive

Buffer

Data stored into MCU
receive register after
transmission of second byte

Data stored into MCU
receive register after
transmission of third byte

DOO

21

20 19 18 17 16

15 14 13 12 11 10 9

8

7654321 0

OL OH 21 20 19 18 17 16

15 14 13 12 11 10 9 8

76 54 3210

RHL

CS

SCK

SDO/RDY

MCU

Data stored into MCU
receive register after
transmission of first byte

Receive

Buffer

Data stored into MCU
receive register after
transmission of second byte

Data stored into MCU
receive register after
transmission of third byte

Data stored into MCU
receive register after
transmission of fourth byte

DR

OO

21 20 19 18 17 16 14 13 12 11 10 9 6 5 4 3 2

0

OH OL 21 20 19 18 17

15 14 13 12 11 10 9

7654321 0DR

8

16

15 7

8

1

HL

5.5 Using The MCP3550/1/3 with Microcontroller (MCU) SPI Ports

It is required that the microcontroller SPI port be
configured to clock out data on the falling edge of clock
and latch data in on the rising edge. Figure 5-6 depicts
the operation shown in SPI mode 1,1, which requires
that the SCK from the MCU idles in the High state,
while Figure 5-7 shows the similar case of SPI Mode
0,0, where the clock idles in the Low state. The
waveforms in the figures are examples of an MCU
operating the SPI port in 8-bit mode, and the
MCP3550/1/3 devices do not require data in 8-bit
groups.

In SPI mode 1,1, data is read using only 24 clocks or
three byte transfers. The data ready bit must be read
by testing the SDO/RDY

line prior to a falling edge of

the clock.

In SPI mode 0,0, data is read using 25 clocks or four
byte transfers. Please note that the data ready bit is
included in the transfer as the first bit in this mode.

FIGURE 5-6: SPI Communication – Mode 1,1.

FIGURE 5-7: SPI Communication – Mode 0,0.

 2005-2014 Microchip Technology Inc. DS20001950F-page 25

MCP3550/1/3

NOTES:

DS20001950F-page 26  2005-2014 Microchip Technology Inc.

6.0 PACKAGING INFORMATION

Legend: XX...X Customer-specific information

Y Year code (last digit of calendar year)
YY Year code (last 2 digits of calendar year)
WW Week code (week of January 1 is week ‘01’)
NNN Alphanumeric traceability code
Pb-free JEDEC

®

designator for Matte Tin (Sn)

* This package is Pb-free. The Pb-free JEDEC designator ( )

can be found on the outer packaging for this package.

Note: In the event the full Microchip part number cannot be marked on one line, it will

be carried over to the next line, thus limiting the number of available
characters for customer-specific information.

3

e

8-Lead MSOP (3x3 mm) Example

3553E

425256

8-Lead SOIC (3.90 mm)

Example (MCP3550)

NNN

3550-50E

SN^^ 1425

256

MCP3551E

SN^^ 1425

256

3

e

Example (MCP3551)

6.1 Package Marking Information

MCP3550/1/3

3

e

3

e

 2005-2014 Microchip Technology Inc. DS20001950F-page 27

MCP3550/1/3

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

DS20001950F-page 28  2005-2014 Microchip Technology Inc.

MCP3550/1/3

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

 2005-2014 Microchip Technology Inc. DS20001950F-page 29

MCP3550/1/3

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

DS20001950F-page 30  2005-2014 Microchip Technology Inc.

MCP3550/1/3

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

 2005-2014 Microchip Technology Inc. DS20001950F-page 31

MCP3550/1/3

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

DS20001950F-page 32  2005-2014 Microchip Technology Inc.

MCP3550/1/3

 !"#$%

& !"#$%&"'""($)%

*++&&&!!+$

 2005-2014 Microchip Technology Inc. DS20001950F-page 33

MCP3550/1/3

NOTES:

DS20001950F-page 34  2005-2014 Microchip Technology Inc.

APPENDIX A: REVISION HISTORY

Revision F (July 2014)

The following is the list of modifications:

1. Updated the Serial Timings table.

Revision E (April 2009)

The following is the list of modifications:

1. DC Characteristics Table, Conversion Times:

Changed all minimums from -1.0% to -2.0%.
Changed typical for MCP3551 from 72.73 to

73.1. Changed all maximums from +1.0% to
+2.0%.

2. Packaging Outline drawings updated.

Revision D (January 2007)

The following is the list of modifications:

• This update includes revisions to the packaging

diagrams.

MCP3550/1/3

Revision C (December 2005)

The following is the list of modifications:

• Added MCP3550-50, MCP3550-60 references

throughout this document.

Revision B (October 2005)

The following is the list of modifications:

• Changed LSb refefences to LSB.

Revision A (September 2005)

• Original Release of this Document.

 2005-2014 Microchip Technology Inc. DS20001950F-page 35

MCP3550/1/3

NOTES:

DS20001950F-page 36  2005-2014 Microchip Technology Inc.

MCP3550/1/3

Device: MCP3550-50: Single-Channel 22-Bit Delta-Sigma ADC

MCP3550T-50: Single-Channel 22-Bit Delta-Sigma ADC

(Tape and Reel)
MCP3550-60: Single-Channel 22-Bit Delta-Sigma ADC
MCP3550T-60: Single-Channel 22-Bit Delta-Sigma ADC

(Tape and Reel)
MCP3551: Single-Channel 22-Bit Delta-Sigma ADC
MCP3551T: Single-Channel 22-Bit Delta-Sigma ADC

(Tape and Reel)
MCP3553: Single-Channel 22-Bit Delta-Sigma ADC
MCP3553T: Single-Channel 22-Bit Delta-Sigma ADC

(Tape and Reel)

Temperature Range: E = -40°C to +125°C

Package: MS = Plastic MSOP, 8-lead

SN = Plastic SOIC (150 mil Body), 8-lead

Examples:

a) MCP3550-50E/MS: Extended Temp.,

8LD MSOP

b) MCP3550T-50E/MS: Tape and Reel,

Extended Temp.,
8LD MSOP

c) MCP3550-60E/SN: Extended Temp.,

8LD SOIC

d) MCP3550T-60E/SN: Tape and Reel,

Extended Temp.,
8LD SOIC

a) MCP3551-E/MS: Extended Temp.,

8LD MSOP

b) MCP3551T-E/MS: Tape and Reel,

Extended Temp.,
8LD MSOP

a) MCP3553-E/SN: Extended Temp.,

8LD SOIC

b) MCP3553T-E/SN: Tape and Reel,

Extended Temp.,
8LD SOIC

PART NO . –X /XX

PackageTemperature

Range

Device

PRODUCT IDENTIFICATION SYSTEM

To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

 2005-2014 Microchip Technology Inc. DS20001950F-page 37

MCP3550/1/3

NOTES:

DS20001950F-page 38  2005-2014 Microchip Technology Inc.

Note the following details of the code protection feature on Microchip devices:

YSTEM

CERTIFIED BY DNV

== ISO/TS 16949 ==

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrity of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR
WARRANTIES OF ANY KIND WHETHER EXPRESS OR
IMPLIED, WRITTEN OR ORAL, STATUTORY OR
OTHERWISE, RELATED TO THE INFORMATION,
INCLUDING BUT NOT LIMITED TO ITS CONDITION,
QUALITY, PERFORMANCE, MERCHANTABILITY OR
FITNESS FOR PURPOSE
arising from this information and its use. Use of Microchip
devices in life support and/or safety applications is entirely at
the buyer’s risk, and the buyer agrees to defend, indemnify and
hold harmless Microchip from any and all damages, claims,
suits, or expenses resulting from such use. No licenses are
conveyed, implicitly or otherwise, under any Microchip
intellectual property rights.

. Microchip disclaims all liability

Trademarks

The Microchip name and logo, the Microchip logo, dsPIC,
FlashFlex, flexPWR, JukeBlox, K
LANCheck, MediaLB, MOST, MOST logo, MPLAB,
OptoLyzer, PIC, PICSTART, PIC
SST, SST Logo, SuperFlash and UNI/O are registered
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.

The Embedded Control Solutions Company and mTouch are
registered trademarks of Microchip Technology Incorporated
in the U.S.A.

Analog-for-the-Digital Age, BodyCom, chipKIT, chipKIT logo,
CodeGuard, dsPICDEM, dsPICDEM.net, ECAN, In-Circuit
Serial Programming, ICSP, Inter-Chip Connectivity, KleerNet,
KleerNet logo, MiWi, MPASM, MPF, MPLAB Certified logo,
MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code
Generation, PICDEM, PICDEM.net, PICkit, PICtail,
RightTouch logo, REAL ICE, SQI, Serial Quad I/O, Total
Endurance, TSHARC, USBCheck, VariSense, ViewSpan,
WiperLock, Wireless DNA, and ZENA are trademarks of
Microchip Technology Incorporated in the U.S.A. and other
countries.

SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.

Silicon Storage Technology is a registered trademark of
Microchip Technology Inc. in other countries.

GestIC is a registered trademarks of Microchip Technology
Germany II GmbH & Co. KG, a subsidiary of Microchip
Technology Inc., in other countries.

All other trademarks mentioned herein are property of their
respective companies.

© 2005-2014, Microchip Technology Incorporated, Printed in
the U.S.A., All Rights Reserved.

ISBN: 978-1-63276-389-1

EELOQ, KEELOQ logo, Kleer,

32

logo, RightTouch, SpyNIC,

QUALITY MANAGEMENT S

 2005-2014 Microchip Technology Inc. DS20001950F-page 39

Microchip received ISO/TS-16949:2009 certification for its worldwide
headquarters, design and wafer fabrication facilities in Chandler and
Tempe, Arizona; Gresham, Oregon and design centers in California
and India. The Company’s quality system processes and procedures
are for its PIC
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.

®

MCUs and dsPIC® DSCs, KEELOQ

®

code hopping

Worldwide Sales and Service

AMERICAS

Corporate Office

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DS20001950F-page 40  2005-2014 Microchip Technology Inc.