MCP3422A1-E/MS Microchip Technology, MCP3422A1-E/MS Datasheet - Page 34

• Manufacturer Part Number: MCP3422A1-E/MS
• Description: 18-Bit, Multi-Channel Delta-Sigma ADC w/ I2C Interface and On-Board Reference ; 8L MSOP 3x3mm
• Manufacturer: Microchip Technology

MCP3422/3/4
Figure
for four-channel thermocouple temperature measure-
ment applications.
FIGURE 6-6:
With Type K thermocouple, it can measure tempera-
ture from 0°C to 1250°C degrees. The full scale output
range of the Type K thermocouple is about 50 mV. This
provides 40 µV/°C (= 50 mV/1250°C) of measurement
resolution.
get for sensor signal using the MCP3422/3/4 device
with 18 bits and PGA = 8 settings. With this configura-
tion, the MCP3424 can detect the input signal level as
low as approximately 2 µV. The internal PGA boosts
the input signal level eight times. The 40 µV/°C input
from the thermocouple is amplified internally to
320 µV/°C before the conversion takes place. This
results in 20.48 LSB/°C output codes. This means
there are about 20 LSB output codes (or about 4.32
bits) per 1°C of change in temperature.
DS22088B-page 34
Thermocouple Sensor
Heat
6-6, shows an example of using the MCP3424
Equation 6-1
MCP9800
MCP9800
Four-Channel Thermocouple Applications.
shows the measurement bud-
Isothermal Block
SDA
SCL
SDA
SCL
0.1 µF
10 µF
1
2
3
4
5
6
7
SDA
CH1+
CH2+
5 kΩ
CH1-
SDA
CH2-
V
V
SS
DD
MCP3424
CH4+
CH3+
CH4-
CH3-
Adr1
Adr0
SCL
EQUATION 6-1:
Where:
Detectable Input Signal Level
Input Signal Level after gain of 8:
14
13
12
11
10
1 LSB
9
8
No. of LSB/°C
SCL
5 kΩ
(MASTER)
T
O
MCU
V
V
=
DD
DD
15.625 µV with 18 bit configuration
SDA
=
SDA
Isothermal Block
320
------------------------ -
=
15.625
SCL
MCP9800
MCP9800
=
© 2008 Microchip Technology Inc.
(
μ
40
SCL
1.953125μV for PGA
V/°C
μ
μ
V/°C
V
=
=
15.625
) 8
20.48 Codes/°C
•
=
μ
V/PGA
320
μ
V/°C
=
8