18-Bit ADC with I2C Interface and Onboard Reference DS

56 Pages·2009·0.92 MB·English

by  Microchip Technology Inc

MCP3426/7/8
16-Bit, Multi-Channel ΔΣ Analog-to-Digital Converter with
2
I C™ Interface and On-Board Reference
Features Description

• 16-bit ΔΣ ADC with Differential Inputs: The MCP3426, MCP3427 and MCP3428 devices
- 2 channels: MCP3426 and MCP3427 (MCP3426/7/8) are the low noise and high accuracy
16Bit Delta-Sigma Analog-to-Digital (ΔΣ A/D) Con-
- 4 channels: MCP3428
verter family members of the MCP342X series from
• Differential Input Full Scale Range: -V to
REF Microchip Technology Inc. These devices can convert
+V
REF analog inputs to digital codes with up to 16 bits of reso-
• Self Calibration of Internal Offset and Gain per
lution.
Each Conversion
The MCP3426 and MCP3427 devices have two
• On-Board Voltage Reference (V ):
REF differential input channels and the MCP3428 has four
- Accuracy: 2.048V ± 0.05%
differential input channels. All electrical properties of
- Drift: 15ppm/°C these three devices are the same except the
• On-Board Programmable Gain Amplifier (PGA): differences in the number of input channels and I2C
address bit selection options.
- Gains of 1,2, 4 or 8
• INL: 10ppm of Full Scale Range These devices can output analog-to-digital conversion
results at rates of 15 (16-bit mode), 60 (14-bit mode), or
• Programmable Data Rate Options:
240 (12-bit mode) samples per second depending on
- 15SPS (16 bits)
the user controllable configuration bit settings using the
- 60SPS (14 bits) two-wire I2C serial interface. During each conversion,
- 240SPS (12 bits) the device calibrates offset and gain errors
• One-Shot or Continuous Conversion Options automatically. This provides accurate conversion
• Low Current Consumption (V = 3V): results from conversion to conversion over variations in
DD
temperature and power supply fluctuation.
- Continuous Conversion: 135µA typical
- One-Shot Conversion with 1SPS: The device has an on-board 2.048V reference voltage,
- 9µA typical for 16 bit mode which enables an input range of ±2.048V differentially
- 2.25µA typical for 14 bit mode (full scale range = 4.096/PGA).
- 0.56µA typical for 12 bit mode The user can select the gain of the on-board
• On-Board Oscillator programmable gain amplifier (PGA) using the
• I2C™ Interface: configuration register bits (gain of x1, x2, x4, or x8).
This allows the MCP3426/7/8 devices to convert a very
- Standard, Fast and High Speed Modes
weak input signal with high resolution.
- User configurable two external address
selection pins for MCP3427 and MCP3428 The MCP3426/7/8 devices have two conversion
modes: (a) One-Shot Conversion mode and
• Single Supply Operation: 2.7V to 5.5V
(b)Continuous Conversion mode. In the One-Shot
• Extended Temperature Range: -40°C to +125°C
conversion mode, the device performs a single
conversion and enters a low current standby
Typical Applications
(shutdown) mode automatically until it receives another
conversion command. This reduces current
• Portable Instrumentation and Consumer Goods
consumption greatly during idle periods. In continuous
• Temperature Sensing with RTD, Thermistor, and
conversion mode, the conversion takes place
Thermocouple
continuously at the configured conversion speed. The
• Bridge Sensing for Pressure, Strain, and Force
device updates its output buffer with the most recent
• Weigh Scales and Battery Fuel Gauges conversion data.
• Factory Automation Equipment
The devices operate from a single 2.7V to 5.5V power
supply and have a two-wire I2C compatible serial
interface for a standard (100kHz), fast (400kHz), or
high-speed (3.4MHz) mode.
© 2009 Microchip Technology Inc. DS22226A-page 1
MCP3426/7/8
The I2C address bits for the MCP3427 and MCP3428 The MCP3426 is available in 8-pin SOIC, DFN, and
are selected by using two external I2C address MSOP packages. The MCP3427 is available in 10-pin
selection pins (Adr0 and Adr1). The user can configure DFN, and MSOP packages. The MCP3428 is available
the device to one of eight available addresses by in 14-pin SOIC and TSSOP packages.
connecting these two address selection pins to V ,
DD
V or float. The I2C address bits of the MCP3426 are
SS
programmed at the factory during production.
Package Types
MSOP, SOIC MSOP SOIC, TSSOP
CH1+ 1 8 CH2- CH1+ 1 10 Adr1 CH1+ 1 14 CH4-
CH1- 2 MC 7 CH2+ CH1- 2 MC 9 Adr0 CH1- 2 M 13 CH4+
VSDDDA 34 P3426 56 VSSCSL CCVHHSS22+- 534 P3427 678 SVSCDDDLA CCHH22+- 34 CP342 1112 CCHH33+-
VSS 5 8 10 Adr1
VDD 6 9 Adr0
MCP3426 MCP3427 SDA 7 8 SCL
2x3DFN * 3x3DFN *
CH1+ 1 8 CH2- CH1+ 1 10 Adr1
CH1- 2 EP 7 CH2+ CH1- 2 9 Adr0
EP
9
VDD 3 6 VSS VSS 3 11 8 SCL
SDA 4 5 SCL CH2+ 4 7 SDA
CH2- 5 6 VDD
* Includes Exposed Thermal Pad (EP); see Table3-1.
MCP3426 Functional Block Diagram
VSS VDD
MCP3426 Voltage Reference
(2.048V)
V
REF
CH1+
SCL
ΔΣ ADC I2C
CH1- PGA
X Converter Interface SDA
U
M
CH2+
CH2- Gain = 1, 2, 4, or 8
Clock
Oscillator
DS22226A-page 2 © 2009 Microchip Technology Inc.
MCP3426/7/8
MCP3427 Functional Block Diagram
VSS VDD
MCP3427
Voltage Reference Adr1
(2.048V)
Adr0
V
REF
CH1+
SCL
CH1- ΔΣ ADC I2C
PGA
X Converter
U Interface SDA
CH2+ M
CH2-
Gain = 1, 2, 4, or 8
Clock
Oscillator
MCP3428 Functional Block Diagram
VSS VDD
MCP3428
CH1+
Voltage Reference Adr1
(2.048V)
CH1-
Adr0
V
REF
CH2+
SCL
CH2- X ΔΣ ADC I2C
U PGA
M Converter
Interface SDA
CH3+
CH3-
Gain = 1, 2, 4, or 8
Clock
CH4+ Oscillator
CH4-
© 2009 Microchip Technology Inc. DS22226A-page 3
MCP3426/7/8
NOTES:
DS22226A-page 4 © 2009 Microchip Technology Inc.
MCP3426/7/8
1.0 ELECTRICAL †Notice: Stresses above those listed under “Maximum Rat-
CHARACTERISTICS ings” may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
Absolute Maximum Ratings†
operational listings of this specification is not implied.
Exposure to maximum rating conditions for extended periods
V ...................................................................................7.0V
DD
may affect device reliability.
All inputs and outputs .......................V –0.4V to V +0.4V
SS DD
Differential Input Voltage ......................................|V - V |
DD SS
Output Short Circuit Current ................................Continuous
Current at Input Pins ....................................................±2mA
Current at Output and Supply Pins ............................±10mA
Storage Temperature....................................-65°C to +150°C
Ambient Temp. with power applied...............-55°C to +125°C
ESD protection on all pins ................≥ 6kV HBM, ≥ 400VMM
Maximum Junction Temperature (T )..........................+150°C
J
ELECTRICAL CHARACTERISTICS
Electrical Specifications: Unless otherwise specified, all parameters apply for T = -40°C to +85°C, V = +5.0V, V = 0V,
A DD SS
CHn+ = CHn- = V /2, V = V /2. All ppm units use 2*V as differential full scale range.
REF INCOM REF REF
Parameters Sym Min Typ Max Units Conditions
Analog Inputs
Differential Full Scale Input FSR — ±2.048/PGA — V V = [CHn+ - CHn-]
IN
Voltage Range
Maximum Input Voltage Range V -0.3 — V +0.3 V (Note1)
SS DD
Differential Input Impedance Z (f) — 2.25/PGA — MΩ During normal mode operation
IND
(Note2)
Common Mode input Z (f) — 25 — MΩ PGA = 1, 2, 4, 8
INC
Impedance
System Performance
Resolution and No Missing 12 — — Bits DR = 240SPS
Codes 14 — — Bits DR = 60SPS
(Effective Number of Bits)
16 — — Bits DR = 15SPS
(Note3)
Data Rate DR 176 240 328 SPS 12 bits mode
(Note4)
44 60 82 SPS 14 bits mode
11 15 20.5 SPS 16 bits mode
Output Noise — 2.5 — µV T = +25°C, DR =15 SPS,
RMS A
PGA = 1, V + = V - = GND
IN IN
Integral Non-Linearity INL — 10 — ppm of DR = 15 SPS
FSR (Note5)
Internal Reference Voltage V — 2.048 — V
REF
Gain Error (Note6) — 0.1 — % PGA = 1, DR = 15 SPS
PGA Gain Error Match (Note6) — 0.1 — % Between any 2 PGA settings
Gain Error Drift (Note6) — 15 — ppm/°C PGA=1, DR=15 SPS
Note 1: Any input voltage below or greater than this voltage causes leakage current through the ESD diodes at the input pins.
This parameter is ensured by characterization and not 100% tested.
2: This input impedance is due to 3.2pF internal input sampling capacitor.
3: This parameter is ensured by design and not 100% tested.
4: The total conversion speed includes auto-calibration of offset and gain.
5: INL is the difference between the endpoints line and the measured code at the center of the quantization band.
6: Includes all errors from on-board PGA and V .
REF
7: This parameter is ensured by characterization and not 100% tested.
8: MCP3427 and MCP3428 only.
9: Addr_Float voltage is applied at address pin.
10: No voltage is applied at address pin (left “floating”).
© 2009 Microchip Technology Inc. DS22226A-page 5
MCP3426/7/8
ELECTRICAL CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise specified, all parameters apply for T = -40°C to +85°C, V = +5.0V, V = 0V,
A DD SS
CHn+ = CHn- = V /2, V = V /2. All ppm units use 2*V as differential full scale range.
REF INCOM REF REF
Parameters Sym Min Typ Max Units Conditions
Offset Error V — 30 — µV PGA = 1
OS
DR = 15SPS
Offset Drift vs. Temperature — 50 — nV/°C
Common-Mode Rejection — 105 — dB at DC and PGA =1,
— 110 — dB at DC and PGA =8, T = +25°C
A
Gain vs. V — 5 — ppm/V T = +25°C, V = 2.7V to 5.5V,
DD A DD
PGA = 1
Power Supply Rejection at DC — 100 — dB T = +25°C, V = 2.7V to 5.5V,
A DD
Input PGA = 1
Power Requirements
Voltage Range V 2.7 — 5.5 V
DD
Supply Current during I — 145 180 µA V = 5.0V
DDA DD
Conversion
— 135 — µA V = 3.0V
DD
Supply Current during Standby I — 0.3 1 µA V = 5.0V
DDS DD
Mode
I2C Digital Inputs and Digital Outputs
High level input voltage V 0.7V — V V at SDA and SCL pins
IH DD DD
Low level input voltage V — — 0.3V V at SDA and SCL pins
IL DD
Low level output voltage V — — 0.4 V I = 3mA
OL OL
Hysteresis of Schmidt Trigger V 0.05V — — V f = 100kHz
HYST DD SCL
for inputs (Note7)
Supply Current when I2C bus I — — 10 µA Device is in standby mode while
DDB
line is active I2C bus is active
Input Leakage Current I — — 1 µA V = 5.5V
ILH IH
I -1 — — µA V = GND
ILL IL
Logic Status of I2C Address Pins (Note8)
Adr0 and Adr1 Pins Addr_Low V — 0.2V V The device reads logic low.
SS DD
Adr0 and Adr1 Pins Addr_High 0.75V — V V The device reads logic high.
DD DD
Adr0 and Adr1 Pins Addr_Float 0.35V — 0.6V V Read pin voltage if voltage is
DD DD
applied to the address pin.
(Note9)
— V /2 — Device outputs float output
DD
voltage (V /2) on the address
DD
pin, if left “floating”. (Note10)
Pin Capacitance and I2C Bus Capacitance
Pin capacitance C — 4 10 pF
PIN
I2C Bus Capacitance C — — 400 pF
b
Note 1: Any input voltage below or greater than this voltage causes leakage current through the ESD diodes at the input pins.
This parameter is ensured by characterization and not 100% tested.
2: This input impedance is due to 3.2pF internal input sampling capacitor.
3: This parameter is ensured by design and not 100% tested.
4: The total conversion speed includes auto-calibration of offset and gain.
5: INL is the difference between the endpoints line and the measured code at the center of the quantization band.
6: Includes all errors from on-board PGA and V .
REF
7: This parameter is ensured by characterization and not 100% tested.
8: MCP3427 and MCP3428 only.
9: Addr_Float voltage is applied at address pin.
10: No voltage is applied at address pin (left “floating”).
DS22226A-page 6 © 2009 Microchip Technology Inc.
MCP3426/7/8
TEMPERATURE CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, T = -40°C to +125°C, V = +5.0V, V = 0V.
A DD SS
Parameters Sym Min Typ Max Units Conditions
Temperature Ranges
Specified Temperature Range T -40 — +85 °C
A
Operating Temperature Range T -40 — +125 °C
A
Storage Temperature Range T -65 — +150 °C
A
Thermal Package Resistances
Thermal Resistance, 8L-DFN (2x3) θ — 84.5 — °C/W
JA
Thermal Resistance, 8L-MSOP θ — 211 — °C/W
JA
Thermal Resistance, 8L-SOIC θ — 149.5 — °C/W
JA
Thermal Resistance, 10L-DFN (3x3) θ — 57 — °C/W
JA
Thermal Resistance, 10L-MSOP θ — 202 — °C/W
JA
Thermal Resistance, 14L-SOIC θ — 120 — °C/W
JA
Thermal Resistance, 14L-TSSOP θ — 100 — °C/W
JA
© 2009 Microchip Technology Inc. DS22226A-page 7
MCP3426/7/8
NOTES:
DS22226A-page 8 © 2009 Microchip Technology Inc.
MCP3426/7/8
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 indicated, T = -40°C to +85°C, V = +5.0V, V = 0V, CHn+ = CHn- = V /2,
A DD SS REF
V = V /2.
INCOM REF

0.005 12
R)
S
% F 0.004 ms) 10 PGA = 1
y ( V, r 8
nlinearit 00..000023 PGA = 4 PGA = 1 PGA = 8 Noise (µ 6 PGA = 2
egral No 0.001 PGA = 2 Output 24 PGA = 4
Int 0 0 PGA = 8
2.5 3 3.5 4 4.5 5 5.5 -100 -75 -50 -25 0 25 50 75 100
V (V) Input Signal (% of FSR)
DD
FIGURE 2-1: INL vs. Supply Voltage FIGURE 2-4: Output Noise vs. Input
(V ). Voltage.
DD
0.005
2
PGA = 1 TA= +25°C
1.5
0.004
PGA = 8
R) mV) 1
INL (% FS 000...000000123 2.7V Total Error (-00-..1505 PGA = 4 PGA = 2
-1.5
5V
0 -2
-60 -40 -20 0 20 40 60 80 100 120 140 -100 -75 -50 -25 0 25 50 75 100
Temperature (oC) Input Voltage (% of Full-Scale)
FIGURE 2-2: INL vs. Temperature. FIGURE 2-5: Total Error vs. Input Voltage.
0.2
20
15 VDD = 5V R) 0.1
et Error (µV) 1-0505 PGA = 4PGA = 8 rror (% of FS---000...3210 PGA = 8 PGA = 1
s-10 E
Off--2105 PGA = 1 PGA = 2 Gain --00..54 PGA = 2 PGA = 4
-25 -0.6
-40 -20 0 20 40 60 80 100 120 140 -60 -40 -20 0 20 40 60 80 100 120 140
Temperature (oC) Temperature (°C)
FIGURE 2-3: Offset Error vs. FIGURE 2-6: Gain Error vs. Temperature.
Temperature.
© 2009 Microchip Technology Inc. DS22226A-page 9
MCP3426/7/8
Note: Unless otherwise indicated, T = -40°C to +85°C, V = +5.0V, V = 0V, CHn+ = CHn- = V /2,
A DD SS REF
V = V /2.
INCOM REF
200 5
180 4
VDD = 5.5V %)
µA)114600 Drift ( 3
I(DDA 110200 VDD = 2.7V cillator 12 VDD = 2.7V
VDD = 5.0V Os
80 0
VDD = 5.0V
60 -1
-60 -40 -20 0 20 40 60 80 100 120 140
-60 -40 -20 0 20 40 60 80 100 120 140
Temperature (°C) Temperature (°C)
FIGURE 2-7: I vs. Temperature. FIGURE 2-10: Oscillator Drift vs.
DDA
Temperature.
1 0
-10 Data Rate = 15 SPS
0.9
-20
00..78 VDD = 5.5V dB) --4300
A) 0.6 e ( -50
I (µDDS 000...345 VDD = 5.0V Magnitud ----98760000
0.2 -100
0.1 VDD = 2.7V -110
0 -120
-60 -40 -20 0 20 40 60 80 100 120 140 0.1 1 10 100 110k00 11000k00
Temperature (°C) Input Signal Frequency (Hz)
FIGURE 2-8: I vs. Temperature. FIGURE 2-11: Frequency Response.
DDS
14
12 VDD = 5.0V VDD = 5.5V
10
A) 8
µ
(DB 6 VDD = 4.5V
D
I
4
2 V = 2.7V
DD
0
-60 -40 -20 0 20 40 60 80 100 120 140
Temperature (°C)
FIGURE 2-9: I vs. Temperature.
DDB
DS22226A-page 10 © 2009 Microchip Technology Inc.