2005 Microchip Technology Inc.
DS21950B-page 1
MCP3551/3
Features
22-bit ADC in Small 8-pin MSOP Package with
Automatic Internal Offset and Gain Calibration
Low-Output Noise of 2.5 V
RMS
with Effective
Resolution of 21.9 bits (MCP3551)
3 V 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
TM
Interface
Ultra-Low Conversion Current (MCP3551):
- 100 A typical (V
DD
= 2.7V)
- 120 A typical (V
DD
= 5.0V)
Differential Input with V
SS
to V
DD
Common Mode
Range
2.7V to 5.5V Single-Supply Operation
Extended Temperature Range:
- -40C to +125C
Applications
Weigh Scales
Direct Temperature Measurement
6-digit DVMs
Instrumentation
Data Acquisition
Strain Gauge Measurement
Block Diagram
Description
The Microchip Technology Inc. MCP3551/3 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 V
RMS
, with a total
unadjusted error of 10 ppm. The family exhibits 6 ppm
Integral Non-Linearity (INL) error, 3 V offset error and
less than 2 ppm full-scale error. The MCP3551/3
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 MCP3551/3 devices operate from -40C to +125C
and are available in the space-saving 8-pin MSOP and
SOIC packages.
Package Types:
Device Selection Table
V
SS
V
IN
+
V
IN
-
SCK
V
DD
SDO
CS
S
I
NC
4
Internal
S
e
r
i
a
l
In
te
r
f
a
c
e
V
REF
POR
Oscillator
3rd-Order
ADC
Modulator
w/ Internal
Calibration
V
DD
RDY
Part
Number
Sample
Rate
Effective
Resolution
50/60 Hz
Rejection
MCP3551
13.75 sps
21.9 bits
50/60 Hz
(simultaneous)
MCP3553
60 sps
20.6 bits
N/A
V
IN
V
IN
+
MCP3551/3
V
SS
CS
SDO/RDY
1
2
3
4
8
7
6
5 SCK
V
DD
V
REF
SOIC, MSOP
Low-Power, Single-Channel 22-Bit Delta-Sigma ADCs
MCP3551/3
DS21950B-page 2
2005 Microchip Technology Inc.
1.0
ELECTRICAL
CHARACTERISTICS
1.1
Maximum Ratings*
V
DD
...................................................................................7.0V
All inputs and outputs w.r.t V
SS
............. 0.3V to V
DD
+ 0.3V
Difference Input Voltage ....................................... |V
DD
- V
SS
|
Output Short Circuit Current ................................. Continuous
Current at Input Pins ....................................................2 mA
Current at Output and Supply Pins ............................10 mA
Storage Temperature.....................................-65C to +150C
Ambient temp. with power applied ................-55C to +125C
ESD protection on all pins (HBM, MM)
............
6 kV,
400V
Maximum Junction Temperature (T
J
) . .........................+150C
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 the 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 -40C
T
A
+85C, V
DD
= 2.7V or 5.0V.
V
REF
= 2.5V. V
IN
+ = V
IN
- = V
CM
= V
REF
/2. All ppm units use 2*V
REF
as full-scale range. Unless otherwise noted, specification
applies to entire MCP3551/3 family.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Noise Performance (MCP3551)
No Missing Codes
NMC
22
--
--
bits
At DC (Note 5)
Output Noise
e
N
--
2.5
--
V
RMS
Effective Resolution
ER
--
21.9
--
bits RMS
V
REF
= 5V
Noise Performance (MCP3553)
No Missing Codes
NMC
20
--
--
bits
At DC (Note 5)
Output Noise
e
N
--
6
--
V
RMS
Effective Resolution
ER
--
20.6
--
bits RMS
V
REF
= 5V
Conversion Times
MCP3551
t
CONV
-0.5%
72.73
+0.5%
ms
MCP3553
t
CONV
-0.5%
16.67
+0.5%
ms
Accuracy
Integral Non-Linearity
INL
--
2
6
ppm
T
A
= +25C only (Note 2)
Offset Error
V
OS
-12
3
+12
V
T
A
= +25C
--
4
--
V
T
A
= +85C
--
6
--
V
T
A
= +125C
Positive Full-Scale Error
V
FS,P
-10
2
+10
ppm
T
A
= +25C only
Negative Full-Scale Error
V
FS,N
-10
2
+10
ppm
T
A
= +25C 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 V
IN
+ and V
IN
-.
4:
Input impedance is inversely proportional to clock frequency; typical values are for the MCP3551 device. V
REF
= 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. MCP3551 device rejection specifications characterized from 49 to 61 Hz.
2005 Microchip Technology Inc.
DS21950B-page 3
MCP3551/3
Rejection Performance
(1,6)
Common Mode DC Rejection
--
-135
--
dB
V
CM
range from 0 to V
DD
Power Supply DC Rejection
--
-115
--
dB
Common Mode 50/60 Hz Rejection
CMRR
--
-135
--
dB
V
CM
varies from 0V to V
DD
Power Supply 50/60 Hz Rejection
PSRR
--
-85
--
dB
V
DD
varies from 4.5V to 5.5V
Normal Mode 50 or 60 Hz
Rejection
NMRR
--
-85
--
dB
MCP3551 only,
0 < V
CM
< V
DD
,
-V
REF
< V
IN
= (V
IN
+ -V
IN
-) <
+V
REF
Analog Inputs
Differential Input Range
V
IN+
-
V
IN-
-V
REF
--
+V
REF
V
Absolute/Common Mode Voltages
V
SS
- 0.3
--
V
DD
+ 0.3
V
Analog Input Sampling Capacitor
--
10
--
pF
Note 5
Differential Input Impedance
--
2.4
--
M
Shutdown Mode Leakage Current
--
1
--
nA
V
IN
+ = V
IN
- = V
DD
; CS = V
DD
(Note 3)
Reference Input
Voltage Range
0.1
--
V
DD
V
Reference Input Sampling
Capacitor
--
15
--
pF
Note 5
Reference Input Impedance
--
2.4
--
M
Note 4
Shutdown Mode Reference
Leakage Current
--
1
--
nA
V
IN
+ = V
IN
- = V
SS
; CS = V
DD
Power Requirements
Power Supply Voltage Range
V
DD
2.7
--
5.5
V
MCP3551 Supply Current
I
DD
--
120
170
A
V
DD
= 5V
--
100
--
A
V
DD
= 2.7V
MCP3553 Supply Current
I
DD
--
140
185
A
V
DD
= 5V
--
120
--
A
V
DD
= 2.7V
Supply Current, Sleep Mode
I
DDSL
--
10
A
Supply Current, Shutdown Mode
I
DDS
--
--
1
A
CS = SCK = V
DD
Serial Interface
Voltage Input High (CS, SCK)
V
IH
0.7 V
DD
--
--
V
Voltage Input Low (CS, SCK)
V
IL
--
--
0.4
V
Voltage Output High (SDO/RDY)
V
OH
V
DD
- 0.5
--
--
V
V
OH
= 1 mA, V
DD
= 5.0V
Voltage Output Low (SDO/RDY)
V
OL
--
--
0.4
V
V
OH
= -1 mA, V
DD
= 5.0V
Input leakage Current
(CS, SCK)
I
LI
-1
--
1
A
Internal Pin Capacitance
(CS, SCK, SDO/RDY)
C
INT
--
5
--
pF
Note 1
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise indicated, all parameters apply at -40C
T
A
+85C, V
DD
= 2.7V or 5.0V.
V
REF
= 2.5V. V
IN
+ = V
IN
- = V
CM
= V
REF
/2. All ppm units use 2*V
REF
as full-scale range. Unless otherwise noted, specification
applies to entire MCP3551/3 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 V
IN
+ and V
IN
-.
4:
Input impedance is inversely proportional to clock frequency; typical values are for the MCP3551 device. V
REF
= 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. MCP3551 device rejection specifications characterized from 49 to 61 Hz.
MCP3551/3
DS21950B-page 4
2005 Microchip Technology Inc.
TEMPERATURE CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated
Parameters
Sym
Min
Typ
Max
Units
Conditions
Temperature Ranges
Specified Temperature Range
T
A
-40
--
+85
C
Operating Temperature Range
T
A
-40
--
+125
C
Thermal Package Resistances
Thermal Resistance, 8L-MSOP
JA
--
206
--
C/W
Thermal Resistance, 8L-SOIC
JA
--
163
--
C/W
SERIAL TIMINGS
Electrical Specifications: Unless otherwise indicated, all parameters apply at -40C
T
A
+85C,
V
DD
= 3.3V or 5.0V, SDO load = 50 pF.
Parameters
Sym
Min
Typ
Max
Units
Conditions
CLK Frequency
f
SCK
--
--
5
MHz
CLK High
t
HI
90
--
--
ns
CLK Low
t
LO
90
--
--
ns
CLK fall to output data valid
t
DO
0
--
90
ns
CS low to indicate RDY state
t
RDY
0
--
50
ns
CS minimum low time
t
CSL
50
--
--
ns
RDY flag setup time
t
SU
20
--
--
ns
CS rise to output disable
t
DIS
20
--
--
ns
CS disable time
t
CSD
90
--
--
ns
Power-up to CS LOW
t
PUCSL
--
10
--
s
CS High to Shutdown Mode
t
CSHSD
--
10
--
s
2005 Microchip Technology Inc.
DS21950B-page 5
MCP3551/3
FIGURE 1-1:
Serial Timing.
FIGURE 1-2:
Power-up Timing.
t
RDY
t
CSL
t
DO
t
SU
f
SCK
t
HI
t
LO
t
DIS
CS
SDO
SCK
t
CSD
t
CSHSD
/RDY
V
DD
CS
t
PUCSL
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