MCP3550-50-E/MS - Microchip Technology, Inc.

MCP3550/1/3

Features

• 22-bit ADC in Small 8-pin MSOP Package with

Automatic Internal Offset and Gain Calibration

• Low-Output Noise of 2.5 µVRMS with Effective

Resolution of 21.9 bits (MCP3550/1)

• 3 µV Typical Offset Error

• 2 ppm Typical Full-Sc ale 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

DD = 2.7V)

-120µA typical (V

DD = 5.0V)

• Differential Input with VSS to VDD Common Mode

Range

• 2.7V to 5.5V Single-Supply Operation

• Extended Temperature Range:

- -40°C to +125°C

Applications

• Weigh Scales

• Direct Temperature Measurement

• 6-digit DVMs

• Instrumentation

• Data Acquisition

• Strain Gauge Measurement

Block Diagram

Description

The Microchip Technology Inc. MCP3550/1/3 devices

are 2.7V to 5.5V low-power, 22-bit Delta-Sigma Ana-

log-to-Digital Converters (ADCs). The devices offer

output noise as low as 2.5 µVRMS, with a total

unadjusted error of 10 ppm. The family exhibits 6 ppm

Integral Non -Lin eari ty (INL) error, 3 µV of fset error an d

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,

industri al control or process control appli ca tio ns .

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.

Package Types:

Device Selection Table

VSS

VIN+

VIN-

SCK

VDD

SDO

SINC 4

Internal

Ser i a l Interfa c e

VREF

POR

Oscillator

3rd-Order

DS ADC

Modulator

w/ Internal

Calibration

VDD

RDY

Part Number Sample

Rate Effective

Resolution 50/60 Hz

Rejection

MCP3550-50 12.5 sps 21.9 bits 50 Hz

MCP3550-60 15 sps 21.9 bits 60 Hz

MCP3551 13.75 sps 21.9 bits 50/60 Hz

(simultaneous)

MCP3553 60 sps 20.6 bits N/A

VIN–

VIN+

MCP3550/1/3

VSS

SDO/RDY

5SCK

VDD

VREF

SOIC, MSOP

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

MCP3550/1/3

1.0 ELECTRICAL

CHARACTERISTICS

1.1 Maximum Ratings*

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

All inputs and outputs w.r.t VSS .............. -0.3V to VDD + 0.3V

Difference Input Voltage ...................... .................|VDD - VSS|

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 (TJ)..........................+150°C

† Notice: Stresses above those listed under "Maximum

Ratings" may cause permanent damage to the device. This is

a stress rating only and functional operation of th e device at

those or any other conditions above those indicated in the

operation listings of this specification is not implied. Exposure

to maximum rating conditions for extended periods may affect

device reliability.

DC CHARACTERISTICS

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C ≤ TA ≤ +85°C, VDD = 2. 7V or 5.0V.

VREF = 2.5V. VIN+ = VIN- = VCM = VREF/2. All ppm units use 2*VREF as full-scale range. Unless otherwise noted, specification

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 eN—2.5— µV

RMS

Effective Resolution ER — 21.9 — bits RMS VREF = 5V

Noise Performance (MCP3553)

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

Output Noise eN—6—µV

RMS

Effective Resolution ER — 20.6 — bits RMS VREF = 5V

Conversion Times

MCP3550-50 tCONV -1.0% 80 +1.0% ms

MCP3550-60 tCONV -1.0% 66.67 +1.0% ms

MCP3551 tCONV -1.0% 72.73 +1.0% ms

MCP3553 tCONV -1.0% 16.67 +1.0% ms

Accuracy

Integral Non-Linearity INL — ±2 6 ppm TA = +25°C only (Note 2)

Offset Error VOS -12 ±3 +12 µV TA = +25°C

—±4— µVT

A = +85°C

—±6— µVT

A = +125°C

Positive Full-Scale Error VFS,P -10 ±2 +10 ppm TA = +25°C only

Negative Full-Scale Error VFS,N -10 ±2 +10 ppm TA = +25°C only

Offset Drift — 0.040 — ppm/°C

Positive/Negative Full-Scale Error

Drift — 0.028 — ppm/°C

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

2: INL is the difference between the endpoints 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 VIN+ and VIN-.

4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. VREF =5V.

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.

MCP3550/1/3

Rejection Performanc e(1,6)

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

Power Supply DC Rejection — -115 — dB

Common Mode 50/60 Hz Rejection CMRR — -135 — dB VCM varies from 0V to VDD

Power Supply 50/60 Hz Rejection PSRR — -85 — dB MCP3551 only, VDD varies from

4.5V to 5.5V

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

at 50 or 60 Hz respectively, VDD

varies from 4.5V to 5.5V

Normal Mode 50 and 60 Hz

Rejection NMRR — -85 — dB MCP3551 only,

0 < VCM < VDD,

-VREF < VIN = (VIN + - VIN-) < +VREF

Normal Mode 50 or 60 Hz

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

at 50 or 60 Hz respectively,

0 < VCM < VDD,

-VREF < VIN = (VIN + - VIN-) < +VREF

Analog In puts

Differential Input Range VIN+ − VIN- -VREF —+V

REF V

Absolute/Common Mode Voltages VSS - 0.3 — VDD + 0.3 V

Analog Input Sampling Capacitor — 10 — pF Note 5

Differential Input Impedance — 2.4 — MΩ

Shutdown Mode Leakage Current — 1 — nA VIN+ = VIN- = VDD; CS = VDD

(Note 3)

Reference Input

Voltage Range 0.1 — VDD V

Reference Input Sampling

Capacitor —15— pFNote 5

Reference Input Impedance — 2.4 — MΩNote 4

Shutdown Mode Reference

Leakage Current —1— nAV

IN+ = VIN- = V SS; CS = VDD

Power Requirements

Power Supply Volt age Range VDD 2.7 — 5.5 V

MCP3550-50, MCP3551 Supply

Current IDD — 120 170 µA VDD = 5V

— 100 — µA VDD = 2.7V

MCP3550-60, MCP3553 Supply

Current IDD — 140 185 µA VDD = 5V

— 120 — µA VDD = 2.7V

Supply Current, Sleep Mode IDDSL —10 µA

Supply Current, Shut down Mode IDDS —— 1 µACS = SCK = VDD

Serial Interface

Voltage Input High (CS, SCK) VIH 0.7 VDD —— V

Voltage Input Low (CS, SC K) VIL ——0.4 V

Voltage Output High (SDO/RDY)V

OH VDD - 0. 5 — — V VOH = 1 mA, VDD = 5.0V

DC CHARACTERISTICS (CONTINUED)

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C ≤ TA ≤ +85°C, VDD = 2. 7V or 5.0V.

VREF = 2.5V. VIN+ = VIN- = VCM = VREF/2. All ppm units use 2*VREF as full-scale range. Unless otherwise noted, specification

applies to entire MCP3550/1/3 family.

Parameters Sym Min Typ Max Units Conditions

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

2: INL is the difference between the endpoints line and the measured code at the cent er of the quantization band.

3: This current is due to the leakage current and the current due to the offset voltage between VIN+ and VIN-.

4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. VREF =5V.

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.

MCP3550/1/3

Voltage Output Low (SDO/RDY)V

OL ——0.4 VV

OH = -1 mA, VDD = 5.0V

Input leakage Current

(CS, SCK ) ILI -1 — 1 µA

Internal Pin Capacitanc e

(CS, SCK , SDO/RDY)CINT —5— pFNote 1

DC CHARACTERISTICS (CONTINUED)

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C ≤ TA ≤ +85°C, VDD = 2. 7V or 5.0V.

VREF = 2.5V. VIN+ = VIN- = VCM = VREF/2. All ppm units use 2*VREF as full-scale range. Unless otherwise noted, specification

applies to entire MCP3550/1/3 family.

Parameters Sym Min Typ Max Units Conditions

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

2: INL is the difference between the endpoints 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 VIN+ and VIN-.

4: Input impedance is inversely proportional to clock frequency; typical values are for the MCP3550/1 device. VREF =5V.

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.

TEMPERATURE CHARACTERISTICS

Electrical Specifications: Unless otherwise indicated

Parameters Sym Min Typ Max Units Conditions

Temperature Ranges

Specified Temperature Range TA-40 — +85 °C

Operati ng Tempe rature Range TA-40 — +125 °C

Thermal Package Resistances

Thermal Resistance, 8L-MSOP θJA —206—°C/W

Thermal Resistance, 8L-SOIC θJA —163—°C/W

SERIAL TIMINGS

Electrical Specifications: Unless otherwise indicated, all parameters apply at -40°C ≤ TA ≤ +85°C,

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

Parameters Sym Min Typ Max Units Conditions

CLK Frequency fSCK —— 5MHz

CLK High tHI 90 — — ns

CLK Low tLO 90 — — ns

CLK fall to output data va lid tDO 0 — 90 ns

CS low to indicate RDY state tRDY 0 — 50 ns

CS minimum low ti me tCSL 50 — — ns

RDY flag setup time tSU 20 — — ns

CS rise to output disable tDIS 20 — — ns

CS disable time tCSD 90 — — ns

Power-up to CS LOW t PUCSL —10—µs

CS High to Shutdown Mode tCSHSD —10—µs

MCP3550/1/3

FIGURE 1-1: Serial Timing.

FIGURE 1-2: Power-up Timing.

tRDY

tCSL

tDO

tSU

fSCK

tHI tLO

tDIS

SDO

SCK

tCSD tCSHSD

/RDY

VDD

tPUCSL

MCP3550/1/3

2.0 TYPICAL PERFORMANCE CURVES

Note: Unless otherwise specified, TA = +25°C, VDD = 5V, VREF = 2.5V, VSS = 0V, VCM = VREF/2, VIN+ = VIN-.

All ppm units use 2* VREF as full-scale range. Unless otherw i se not ed, grap hs apply to entire MCP3550/1/3 family.

FIGURE 2-1: INL Error vs. Input Voltage

(VDD = 2.7V).

FIGURE 2-2: INL Error vs. Input Voltage

(VDD = 5.0V).

FIGURE 2-3: INL Error vs. Input Voltage

(VDD = 5.0V, VREF = 5V).

FIGURE 2-4: Maximum INL Error vs .

VREF.

FIGURE 2-5: Maximum INL Error vs .

Temperature.

FIGURE 2-6: Output Noise vs. Input

Voltage (VDD = 2.7V).

Note: The g r ap hs and t ables provid ed fol low i ng thi s n ote are a statistical s umm ar y based on a l im ite d n um ber of

samples and are prov ided for informational purposes only. The performance charac teristics 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.

-5

-4

-3

-2

-1

-2.5 -1.5 -0.5 0.5 1.5 2.5

VIN(V)

INL (ppm)

+125 C

+85 C

-40 C

+25 C

-5

-4

-3

-2

-1

-2.5 -1.5 -0.5 0.5 1.5 2.5

VIN (V)

INL (ppm)

+125 C

+85 C

+25 C

- 40 C

-10

-8

-6

-4

-2

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

VIN (V)

INL (ppm)

+125 C

+85 C

+25 C

-40 C

00.511.522.533.544.55

VREF (V)

INL Error (ppm)

-50 -25 0 25 50 75 100 125

Temperature (°C)

Max INL (ppm)

-2.5 -1.5 -0.5 0.5 1.5 2.5

VIN (Volts)

Output Noise (µV RMS)

MCP3553

MCP3550/1

MCP3550/1/3

Note: Unless otherwise specified, TA = +25°C, VDD = 5V, VREF = 2.5V, VSS = 0V, VCM = VREF/2, VIN+ = VIN-.

All ppm units use 2* VREF as full-scale range. Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

FIGURE 2-7: Output Noise vs. Input

Voltage (VDD = 5.0V).

FIGURE 2-8: Output Noise vs. VREF.

FIGURE 2-9: Output Noise vs.VDD.

FIGURE 2-10: Output Noise vs.

Temperature.

FIGURE 2-11: Offset Error vs VDD

(VCM =0V).

FIGURE 2-12: Offset Error vs.

Temperature (VREF = 5.0V).

-2.5 -1.5 -0.5 0.5 1.5 2.5

VIN (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

0.0 1.0 2.0 3.0 4.0 5.0

VREF (V)

Output Nois e (µVRMS)

MCP3550/1

MCP3553

2.533.544.555.5

VDD (V)

Output Noise (µV RMS)

MCP3550/1

MCP3553

-50-250 255075100125

Temperature (°C)

Output Noise (µV RMS)

MCP3550/1

MCP3553

2.533.544.555.5

VDD (V)

Offset (µV)

-50 -25 0 25 50 75 100 125

Temper atu re (°C)

Offset (µV)

MCP3550/1/3

Note: Unless otherwise specified, TA = +25°C, VDD = 5V, VREF = 2.5V, VSS = 0V, VCM = VREF/2, VIN+ = VIN-.

All ppm units are ratioed against 2*VREF . Unless otherwise noted, graphs apply to entire MCP3550/1/3 family.

FIGURE 2-13: Full-Sca le Error vs. VDD.

FIGURE 2-14: Full-Sca le Error vs.

Temperature.

FIGURE 2-15: Full-Sca le Error vs.

Temperature (VREF = 5.0V).

FIGURE 2-16: MCP3550/1 Output Noise

Histogram.

FIGURE 2-17: MCP3553 Output Noise

Histogram.

FIGURE 2-18: Total Unadjusted Error

(TUE) vs. Input Voltage (VDD = 2.7V).

-5

-4

-3

-2

-1

2.533.544.555.5

VDD (V)

Full-Scale Error (ppm)

Positive Full- Scale

Negative Full-Scale

-10

-8

-6

-4

-2

-50 -25 0 25 50 75 100 125

Temperature (°C)

Full-Scale Error (ppm)

Positive Full-Scale

Negative Full - S c a le

-10

-8

-6

-4

-2

-50 -25 0 25 50 75 100 125

Temperature (°C)

Full-Scale Error (ppm)

Positive Full-Scale

Negative Full-Scale

500

1000

1500

2000

2500

3000

3500

4000

-15 -10 -5 0 5 10 15

Output Code (LS B)

Number of Occurrences

VDD = 5V

VREF = 2.5V

VCM = 1.25V

VIN = 0V

TA = 25C

16384

consecutive

readings

200

400

600

800

1000

1200

1400

1600

1800

-15 -10 -5 0 5 10 15

Output Code (LSB)

Number of Occurrences

VDD = 5V

VREF = 2.5V

VCM = 1.25V

VIN = 0V

TA = 25°C

16384 consecutive

readings

-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

VIN (V)

TUE (ppm)

MCP3550/1/3

Note: Unless otherwise specified, TA = +25°C, VDD = 5V, VREF = 2.5V, VSS = 0V, VCM = VREF/2, VIN+ = VIN-.

All pp m units us e 2*V REF as full-scale range. Unless otherwise noted, grap hs appl y to enti re M C P355 0/1 /3 fam il y.

FIGURE 2-19: Total Unadjusted Error

(TUE) vs. Input Voltage.

FIGURE 2-20: Total Unadjusted Error

(TUE) vs. Input Voltage (VREF = 5.0V).

FIGURE 2-21: Maximum TUE vs. VREF.

FIGURE 2-22: Maximum TUE vs.

Temperature.

FIGURE 2-23: Maximum TUE vs. VDD.

FIGURE 2-24: IDDS vs. Temperature.

-5

-4

-3

-2

-1

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

VIN (V)

TUE (ppm)

-10

-8

-6

-4

-2

-5-4-3-2-1012345

VIN (V)

TUE (ppm)

012345

VREF (V)

Maximum TUE (ppm)

-50 -25 0 25 50 75 100 125

Temperat ur e (° C)

Maximum TUE (ppm)

0.5

1.5

2.5

3.5

4.5

2.5 2.7 3 3.3 4 5 5.5

VDD (V)

TUE (ppm)

-0.1

0.1

0.2

0.3

0.4

0.5

0.6

-50-250 255075100125

Temperatu r e ( °C)

IDDS (µA)

MCP3550/1

MCP3553

MCP3550/1/3

Note: Unless otherwise specified, TA = +25°C, VDD = 5V, VREF = 2.5V, VSS = 0V, VCM = VREF/2, VIN+ = VIN-.

All ppm units use 2* VREF as full-scale range. Unless otherw i se not ed, grap hs apply to entire MCP3550/1/3 family.

FIGURE 2-25: IDD vs. VDD.FIGURE 2-26: IDD vs. Temp erature.

100

120

140

160

180

200

2.5 3 3.5 4 4.5 5 5.5

VDD (V)

IDD (µA)

MCP3550-60, MCP3553

MCP3550-50, MCP3550/1

100

120

140

160

-50 -25 0 25 50 75 100 125

Temperatur e (°C)

IDD (µA)

MCP3550-60, MCP3553

MCP3550-50, MCP3550/1

MCP3550/1/3

3.0 PIN DESCRIPTIONS

TABLE 3-1: PIN FUNCTION TABLE

3.1 Voltage Reference (VREF)

The MCP3550/1/3 devices accept single-ended refer-

ence voltages from 0.1V to VDD. Since the 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 refer-

enc e voltag e at th e VREF input pin. A reduced voltage

reference will significantly improve the INL perfor-

mance (see Figure 2-4); the INL max error is

proportional to VREF2.

3.2 Analog Inputs (VIN+, VIN-)

The MCP3550/1/3 devices accept a fully differential

analog input voltage to be connected on the VIN+ and

VIN- input pins. The differential voltage that is con-

verted is defined by VIN = VIN+ – VIN-. Th e di fferen ti al

voltage range specified for ensured accuracy is from

-VREF to +VREF. However, the 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 VSS – 0.3V to VDD + 0.3V. Any voltage above or

below this range will create leakage currents through

the El ectrostatic Discharge (ESD) diodes. T his current

will increase exponentially, degrading the accuracy and

noise performance of the device. The common mode of

the analog inputs sho uld be chosen su ch that bo th th e

differential analog input range and the absolute voltage

range on each pin are within the specified operating

range d efined in Section 1.0 “Electrical Characteris-

tics”.

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 shoul d be ma int ain ed in th e 2.7V to 5.5V range

for specified operation. VSS is the ground pin and the

current return path for both analog and di gital 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 . T he devic e operates in both SPI mode 1,1 and

SPI m ode 0,0. Data is sh ifted o ut of the device on the

falling edge of SCK. Data is latched in on the rising

edge of SCK. During CS high times, the SCK pin can

idle either high or low.

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 Inter-

face”) on the SPI bus through the SDO pin. Data is

clocked out on the falling edge of SCK.

3.6 Chip Select (C S)

CS gates all communication to the device and can be

used to select multiple devices that share the same

SCK and SDO/RDY pins. This pin is also used to

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 Co ntinuo us Conv ersion mode (i .e., add itiona l

inte rnal conv ersi ons will au toma tical ly occur ). CS may

be tied permanently low for two-wire Continuous

Conv ersion mode op erati on. SDO/ RDY enters a high-

impedance state with CS high.

Pin No. Symbol I/O/P Function

REF I Reference Voltage Analog Input Pin

IN+ I Non-inverting Analog Input Pin

IN- I Inverting Analog Input Pin

SS P Grou nd Pin

5 SCK I Ser ial Clock Digital Input Pin

6 SDO/RDY O Data/Ready Digi tal Output Pin

7CS

I Chip Select Digital Input Pin

DD P Pos itive Supply Voltage Pin

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

MCP3550/1/3

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

modif ied SI NC deci mation f ilter, an on-c hip, lo w-noise

internal oscillator, a power supp ly 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,

tempera ture, strai n ga uge, i ndust rial c ontrol or p roces s

control applications. The power supply range for this

produ ct family is 2.7V to 5.5V ; t he temper ature 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) monit oring circuit is in cluded

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 vol tage range and indus trial tempe ratur e rang e.

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

missin g co de per f or ma nc e wit h 21 . 9 Effec tiv e Num be r

of Bits (ENOB). These devices provide single-cycle

conversions with no digital filter settling time. Every

conversion includes an internal offset and gain auto-

calibration to reduce device error. These calibrations

are transparent to the user and are done in real-time

during the conve rsi on. There fore, thes e devi ces 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 MCP3 550 /1/3 dev ices communic ate wit h 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 - lo w. The device ca n com municate 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 inte rnal re giste rs are flus hed b etwee n

conversions. When the device is not converting, it auto-

matically goes into Shutdown mode and, while in this

mode, consumes less than 1 µA.

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

Internal

Oscillator

Third-Order

ΔΣ

Modulator

Digital

Decimation

Filter (SINC4)

SPI 3-wire

Interface

Gain and

Offset

Calibration

Differential

Analog Input Bit Conversion

Code Output

Code

Clock

Charge

Transfer

Reference

Input

Stream

MCP3550/1/3

4.1 MCP3550/1/3 Delta-Sigma

Modulator with Inter nal Offset and

Gain C a libratio n

The converter core of the MCP3550/1/3 devices is a

third-order delta-sigma modulator with automatic gain

and of fset 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

fOSC/4 (see Table 4-1). The high oversampling

implemented in the modulator ensures very high

resolution and high averaging factor to achieve low-

noise specifications. The bit stream output of the mod-

ulator is then processed by the digital decimation filter

in order to pro vide a 22-bi t output code at a da ta rat e 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 MCP3 553 device, a much hi gher output dat a rate is

achiev ed whi le still achieving 20 bit s 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 Filt er

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 modu-

lator 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 communi-

cation, th e RDY flag is set on th e SDO/RDY pin and al l

the internal registers are reset in order to process the

next conversion.

Like the comm only used SIN C filte r, the modifie d SINC

filter in the MCP3550/1/3 family has the main notch

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

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 loc ated at 60 Hz. The MCP35 51 dev ice h as it s

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 mo dification i s intended to widen the ma in notch in

order to be less sensitive to oscillator deviation or line-

frequency 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).

TABLE 4-1: DATA RATE, OUTPUT NOISE AND DIGITAL FILTE R SPECIFICATIONS BY DEVICE

Device Output Data

Rate (tCONV)

(Note)

Output

Noise

(µVRMS)

Primary

Notch

(Hz)

Sample

Frequency

(fS)

Internal

Clock

fOSC

50/60 Hz Rejection

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

50 Hz

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

60 Hz

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

48 Hz to 63 Hz. -

82 dB at 50 Hz and

-88 dB at 60 Hz

MCP3553 16.67 ms 6 240 30720 Hz 122.88 kHz Not Applicable

Note: For the first conversion after exiting Shutdown, tCONV must include an additional 144 fOSC periods before

the conv ersion is complete and the RDY (Ready) flag appears on SDO/RDY.

MCP3550/1/3

FIGURE 4-2: SINC Filter Response,

MCP3550- 50 Devic e.

FIGURE 4-3: SINC Filter Response,

MCP3550- 60 Devic e.

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 (fs).

4.3 Internal Oscil lator

The MCP3550/1/3 devices include a highly stable and

accurate internal oscillator that provides clock signals

to th e delta-s igma A DC with minimu m jitt er. Th e oscil -

lator is a specialized structure with a low temperature

coefficient across the full range of specified operation.

See Table 4-1 for oscillator frequencies.

The conversion time is an integer multiple of the inter-

nal cloc k period and, therefore, ha s the same ac curacy

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 tha t the MCP3551 w ill hav e simu l-

taneous 50 Hz and 60 Hz line frequency rejection and

the MCP3550-50 or MCP3550-60 devices will have

greater than 120 dB rejection (a t 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 en sure 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

digit al SPI interfa ce is async hronous with respect to the

internal clock edges).

-120

-100

-80

-60

-40

-20

0 50 100 150 200

Frequency (Hz)

Attenuation (dB)

-120

-100

-80

-60

-40

-20

0 60 120 180 240

Frequency (Hz)

Attenuat i on (dB)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0 102030405060708090100110

Frequency (Hz)

Attenuation (dB)

-140

-120

-100

-80

-60

-40

-20

0 28160 56320 84480 112640 140800 168960 197120 225280 253440

Frequency (Hz)

Normal Mode Rejection (dB)

MCP3550/1/3

4.4 Different ial Analog Inputs

The MCP3550/1/3 devices accept a fully differential

analog input voltage to be connected to the VIN+ and

VIN- input pins. The differential voltage that is converted

is define d by VIN = VIN+ – V IN-. The di f fe r en tia l vol t age

range specified for ensured accuracy is from -VREF to

+VREF.

The conv erter will output v alid an d usabl e code s 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 outp ut code: OVH and OVL. This fe ature a llo w s for

system calibration of a positive gain error.

The absolute voltage range on these input pins extends

from VSS - 0.3V to VDD + 0.3V. If the input vo lt a ges are

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 Cha racteristics”.

Both the analog differential inputs and the reference

input have switched-capacitor input structures. The

input capacitors are charged and discharged alterna-

tively with the input and the reference in order to

proc ess a conversi on. The charge and discharge of th e

input capacitors create dynamic input currents at the

VIN+ and VIN- input pins inversely proportional to the

sampling capacitor. This current is a function of the

differential input voltages and their respective common

modes. The typical value of the dif ferential input imped-

ance is 2.4 MΩ, with VCM = 2.5V, VDD = V REF = 5V. The

DC leakage current caused by the ESD input diodes,

even th ough o n the order o f 1 nA, can caus e add itiona l

offset errors proportiona l to the source resistance at the

VIN+ and VIN- input pins.

From a transient response standpoint and as a first-

order approximation, these input structures form a

simple RC fil tering c ircui t with the source imped ance i n

series with the RON (switc hed resi stance when closed)

of the input switch a nd the sampling c apacitor. 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 b e 14 ti mes greater t han the in put circuit RC tim e

constant.

4.5 Voltage Reference Input Pin

The MCP3550/1/3 devices accept a single-ended

external reference voltage, to be connected on the

VREF input pin. Internally, the reference voltage for the

ADC is a differential voltage with the non-inverting input

connected to the VREF pin and the inverting input

connected to the VSS pin. The value of the reference

voltage is VREF - VSS and the common mode of the

reference is always (VREF - VSS)/2.

The MCP3550/1/3 devices accept a single-ended

reference voltage from 0.1V to VDD. The converter

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 referenc e volta ge at the VREF input pin. However, a

reduced referen ce v olt age w ill signi ficant ly impro ve th e

INL performance since the INL max error is

proportional to VREF2 (see Figure 2-4).

The charg e and di scha rge of the input c apa citor c reate

dynamic input currents at the VREF input pin inversely

proportional to the sampl ing capacitor, which is a func-

tion of the input reference voltage. The typical value of

the single-ended input impedance is 2.4 MΩ, with

VDD =V

REF = 5V. The DC leakage current caused by

the ESD input diodes, though on the order of 1 nA

typica lly , can cause additi onal gain error pr oportional to

the source resistance at the VREF pin.

4.6 Power-On Reset (POR)

The MCP3550/1/3 devices contain an internal Power-

On Reset (POR) circuit that monitors power supply

voltage VDD during operation. This circuit ensures

correct de vice st art-u p at syste m power-up and power-

down 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 settl ing of t he pow er supply durin g pow er-

up. A 0 .1 µF de coupl ing capaci tor shou ld be mount ed

as close as possible t o the VDD pin, providing additional

transient immunity.

The threshold vol t ag e is s et at 2.2V, with a tol erance of

approximately ±5%. If the supply voltage falls below

this thre shold , the MC P3550 /1/3 devic es wil l be he ld 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.

MCP3550/1/3

Once a power-up event has occurred, the device must

require additional time before a conversion can take

place. Du ring this tim e, all interna l analog circui try 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-u p and powe r-down ev ent unde r typica l st art-up

conditions.

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 the

Shutdown and Sleep modes. During Shutdown mode,

all interna l analog circuitry , including the POR, is turned

off and the device consumes less than 1 µA. When

exiti ng S hutdo wn m ode, t he device must requ ir e ad di-

tional 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

prope r operating poi nt. This timi ng is typically less than

300 µs, which is negligible comp ared to one conversion

time (72.7 ms for MCP3551).

4.8 Sleep Mode

During Sle ep mo de, the devic e i s not co nv erti ng and i s

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

down mode) and t hen back t o a logic-l ow will res tart 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.

VDD

2.2V

2.0V

Reset Normal

Operation ResetStart-up

Time

300 µs

MCP3550/1/3

5.0 SERIAL INTERFACE

5.1 Overview

Serial communication between the microcontroller and

the MCP3550/1/3 devices is achieved using CS, SCK

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 bi t s of conv ers io n dat a and tw o overfl ow

bits. The conversion process takes place via the inter-

nal 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 conver-

sion is the SDO/RDY pin and is 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 remains in a high-impedance state when

CS is hel d hi gh. CS must be low wh en clocking o ut th e

data using SCK and SDO/RDY.

Bit 22 is Overflow High (OVH) when VIN > VRE F – 1 LSB,

OVH toggles to logic ‘1’, detecting an overflow high in

the analog input voltage.

Bit 23 is Overflow Low (OVL) when VIN < -V REF, OVL

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 interfa ce me ani ng erron eo us co mm uni ca tion.

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 -VREF and

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

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

VREF (at ro om te mp erature), meanin g t hat the modul a-

tor will still give accurate output codes with an over-

range 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 con-

vert er ca n be us ed as a 23 - bit t wo' s co mp l em ent co de

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.

SCK

DOO21 20 19 18 17 16 15 14 13 12 11 10 9 87654321 0

READY HLR HI-Z

SDO/RDY

MCP3550/1/3

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

inter nal oscillator cl ocks the delt a-sigma mod ulator and

the SINC filter until a conversion is complete. This

conversion time is tCONV and the timing is shown in

Figure 5-2. At the end of tCONV, the digital filter has

settled complete ly and the re is n o latency in volved w ith

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

Conve rsion. In Single Conve rsion mo de, a consecu tive

convers ion wi ll not autom atica lly b egin. Instea d, after a

single conversion is complete and all four filters have

settled , the device put s the data into the output reg ister

and enters shutd own.

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 availab le in the Ou tput 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.

Int. Osc

tCONV Sleep Shutdown

SCK (opt)

SDO/RDY Hi-Z Hi-Z

x24

Int. Osc

tCONV

Shutdown

SCK (opt)

tCONV tCONV

SDO/RDY Hi-Z

x24

MCP3550/1/3

5.3 Single Conversion Mode

If a ris ing ed ge of Chip Select (CS) occurs during tCONV,

a subsequent conversion will not take place and the

device will enter low-power Shutdown mode after

tCONV completes. This is referred to as Single

Conversion mode. This operation is demonstrated in

Figure 5-3. Note that a falling edge of CS during the

same conversion that detected a rising edge, as in

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

rising edge is seen, the device will enter Sleep, then

Shutdown mode. Once the device has been put into

Single C onve rsion m ode, the dat a mus t be clo cked out

in order for a new conversion to take place. A

subseq uent fal ling edg e on CS during Shutdown mode

will not initiate a new conversion, unless the prior

conversion data has been clocked out of the device.

After the fin al data bit has be en clocked o ut on the 25 th

clock, the SDO/RDY pin 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 conver-

sion, the state of the internal conversion is latched on

the SDO/RDY pin to give ready or busy information. A

High st ate me ans the dev ice is cu rrently performin g an

internal conversion and data cannot be clocked out. A

Low s tat e means the devi ce has finish ed its conver sion

and t he d at a is read y f or retrieval on the fal lin g ed ge 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.

FIGURE 5-4: RDY Functionality in Single

Conversion Mode.

5.4 Continuous Conversion Mode

If no rising edg e of CS occ urs durin g any giv en co nver-

sion per Figure 5-2, a subsequent conversion will take

place and the contents of the previous conversion will

be overwritten. This operation is demonstrated in

Figur e 5-5. O nce conv ersio n outpu t dat a has s ta rted 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 th e next conve rsion in thi s mode.

The su bsequent co nversion d ata to b e read wil l then be

the most recent conversion. The conversion time is

fixed an d cannot be shortened by the risin g 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

FIGURE 5-5: Mo st Cur rent C ontinuo us

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, whic h will indicate the end of

conversion.

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 is seen during tCONV and consecu-

tive conversions ensue. SDO/RDY will be 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 after this

first conversion, the conversion data can be accessed

with the com binati on of SCK and SDO/RD Y. 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).

Note: The R ea dy st at e is latc he d on eac h fal lin g

edge of CS and will not dynamically

update if CS is held low. CS must be

toggled high through low.

tCONV

Int. Osc

SDO/RDY Hi-Z

tCONV

tCONV tCONV

Int. Osc

SCK & SDO/RDY

ABC

Conversion B data is clocked

out of the device here.

MCP3550/1/3

If 24 bits o f data a re required from this conversi on, they

must be ac c ess ed duri ng this communication. You can

terminate data transition by bringing CS high, but the

remaini ng data wil l be lost and the con verter will go into

Shutdown mode. Once the data has been transmitted

by the converter, the SDO/RDY pin will remain in the

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 state.

5.4.2 2-WIRE CONTINUOUS

CONVERSION OPERATION,

(CS TIED PERMANEN TLY LOW)

It is p ossible to use o nly two w ires to c ommunicat e with

the MCP3550/1/3 devices. In this state, the device is

always in Continuous Conversion mode, with internal

conversions continuously occurring. This mo de can be

enter ed by h aving CS lo w during power-up or c hanging

it to a l ow position after p ower-up. If CS is low at power-

up, the first conversion of the converter is initiated

approximately 300 µs after the power supply has

stabilized.

Note: The RDY state is not latched to CS in this

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.

MCP3550/1/3

5.5 Using The MCP3550/1/3 with

Microcontroll er (MCU) SPI Ports

It is req uired that the m icrocontroller SPI port be confi g-

ured 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 cl ock.

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.

SCK

SDO/RDY

MCU

Data stored into MCU receive

first byte

Receive

Buffer

Data stored into MCU receive

second byte

Data stored into MCU receive

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 7 6 5 4 3 2 1 0

RHL

SCK

SDO/RDY

MCU

Data stored into MCU receive

first byte

Receive

Buffer

Data stored into MCU receive

second byte

Data stored into MCU receive

third byte

Data stored into MCU receive

fourth byte

DR OO21 20 19 18 17 16 14 1312 11 10 9 65432 0

OH OL 21 20 19 18 17 15 14 13 12 11 10 9 7 6 5 4 3 2 1 0

15 7

MCP3550/1/3

6.0 PACKAGING INFORMATION

6.1 Package Marking 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 J EDEC designa tor ( )

can be found on the outer packaging for this package.

Note: In the ev ent the fu ll Mic rochip part nu mber ca nnot be m arked o n one lin e, it will

be carried over to the next line, thus limiting the number of available

characters for customer-specific information.

8-Lead SOIC (150 mil) Examples:

XXXXXXXX

XXXXYYWW

NNN

MCP3551E

SN^^ 0715

256

8-Lead MSOP Example:

XXXXXX

YWWNNN 3553E

715256

MCP3550/1/3

8-Lead Plastic Micro Small Outline Package (MS) [MSOP]

otes:

. Pin 1 visual index feature may vary, but must be located within the hatched area.

. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not ex ceed 0.15 mm per side.

. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

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

http://www.microchip.com/packaging

Units MILLIMETERS

Dimension Limits MIN NOM MAX

Number of Pins N 8

Pitch e 0.65 BSC

Overall Height A – – 1.10

Molded Package Thickness A2 0.75 0.85 0.95

Standoff A1 0.00 – 0.15

Overall Width E 4.90 BSC

Molded Package Width E1 3.00 BSC

Overall Length D 3.00 BS C

Foot Length L 0.40 0 .60 0.80

Footprint L1 0.95 REF

Foot Angle φ0° – 8°

Lead Thickness c 0.08 – 0.23

Lead Width b 0.22 – 0. 40

NOTE 1

L1 L

Microchip Technology Drawing C04-111

MCP3550/1/3

8-Lead Plastic Small Outline (SN) – Narrow, 3.90 mm Body [SOIC]

otes:

. Pin 1 visual index feature may vary, but must be located within the hatched area.

. § Significant Characteristic.

. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not ex ceed 0.15 mm per side.

. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

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

http://www.microchip.com/packaging

Units MILLMETERS

Dimension Limits MIN NOM MAX

Number of Pins N 8

Pitch e 1.27 BSC

Overall Height A – – 1.75

Molded Package Thickness A2 1.25 – –

Standoff §A1 0.10 – 0.25

Overall Width E 6.00 BSC

Molded Package Width E1 3.90 BSC

Overall Length D 4.90 BS C

Chamfer (optional) h 0.25 – 0.50

Foot Length L 0.40 – 1. 27

Footprint L1 1.04 REF

Foot Angle φ0° – 8°

Lead Thickness c 0.17 – 0.25

Lead Width b 0.31 – 0. 51

Mold Draft Angle Top α5° – 15°

Mold Draft Angle Bottom β5° – 15°

NOTE 1

12 3

Microchip Technology Drawing C04-057

MCP3550/1/3

APPENDIX A: REVISION HISTORY

Revision A (September 2005)

• Original Release of this Document.

Revision B (October 2005)

• Changed LSb refefences to LSB.

Revision C (December 2005)

• Added MCP3550-50, MCP3550-60 references

throughout this document.

Revision D (January 2007)

• This update includes revisions to the packaging

diagrams.

MCP3550/1/3

NOTES:

MCP3550/1/3

PRODUCT IDENTIFICATION SYSTEM

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

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

PART NO. –X /XX

PackageTemperature

Range

Device

Examples:

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

8LD MSOP.

b) MCP3550/1T-50E/MS:Tape and Reel,

Extend ed Temp.,

8LD MSOP.

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

8LD SOIC.

d) MCP3550/1T-60E/SN:Tape and Reel ,

Extend ed Temp.,

8LD SOIC.

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

8LD MSOP.

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

Extend ed Temp.,

8LD MSOP.

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

8LD SOIC.

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

Extend ed Temp.,

8LD SOIC.

MCP3550/1/3

NOTES:

Information contained in this publication regarding device

applications and the like is provided on ly for your c onvenience

and may be supersed ed by upda t es . It is y our respo ns i bil it y 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. Microchip disclaims all liability

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.

Trademarks

The Microchip name and logo, the Microchip logo, Accuron,

dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro, PICST ART,

PRO MATE, PowerSmart, rfPIC, and SmartShunt are

registered trademarks of Microchip Technology Incorporated

in the U.S.A. and other countries.

AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,

SEEV AL, SmartSensor and The Embedded Control Solutions

Company are registered trademarks of Microchip Technology

Incorporated in the U.S.A.

Analog-for-the-Digital Age, Application Maestro, CodeGuard,

dsPICDEM, dsPICDEM.net, dsPICworks, ECAN,

ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,

In-Circuit Serial Programming, ICSP, ICEPIC , Linear Active

Thermistor, Mindi, MiWi, MPASM, MPLIB, MPLINK, PIC kit,

PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,

PowerInf o, PowerMate, Pow erTool, REAL ICE, rfLAB,

rfPICDEM, Select Mode, Smart Serial, SmartTel, Total

Endurance, UNI/O, WiperLock 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.

All other trademarks mentioned herein are property of their

respective companies.

Printed on recycled paper.

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

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

• Microchip believes that its family of products is one of the most secure famili es of its kind on the market today, when used in the

intended manner and under normal conditions.

• There are dishonest and possibly illegal m ethods 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 Dat a

Sheets. Most likely, the person doing so is engaged in theft of intellec tual 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 c onstantly evolving. We a t Microchip are committed to continuously improving the c ode prot ection f eatures of our

products. Attempts to break Microchip’ s code protection f eature may be a violati on of t he Digit al Millennium Copyright Act. If such act s

allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.

Microchip received ISO/TS-16949:2002 certification for its worldwide

headquarters, design and wafer fabrication facilities in Chandler and

T empe, Arizona, Gresham, Oregon and Mountain View , California. The

Company’s quality system processes and procedures are for its PIC®

MCUs and dsPIC DSCs, KEELOQ® code hopping 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.

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12/08/06