Microchip Technology MCP3422EV Data Sheet
MCP3422/3/4
DS22088C-page 34
© 2009 Microchip Technology Inc.
, shows an example of using the
MCP3424 for four-channel thermocouple temperature
measurement applications.
measurement applications.
FIGURE 6-6:
Four-Channel Thermocouple Applications.
With Type K thermocouple, it can measure
temperature 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.
temperature 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.
shows the measurement budget for sensor signal using
the MCP3422/3/4 device with 18 bits and
PGA = 8 settings. With this configuration, 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.
the MCP3422/3/4 device with 18 bits and
PGA = 8 settings. With this configuration, 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.
EQUATION 6-1:
5 k
Ω
V
DD
4
5
6
9
CH2-
V
SS
CH3+
3
12
CH2+
CH3-
2
13
CH1-
CH4+
1
14
CH1+
CH4-
7
8
SDA
SCL
V
DD
11
10
0.1 µF
10 µF
T
O
MCU
(MASTER)
MCP9800
MCP9800
MCP9800
MCP9800
Isothermal Block
Isothermal Block
Thermocouple Sensor
Heat
SCL
SDA
SDA
SCL
SDA
SCL
V
DD
SDA
SCL
SDA
SCL
Adr1
Adr0
5 k
Ω
MCP3424
Input Signal Level after gain of 8:
Where:
1 LSB
=
15.625 µV with 18 bit configuration
Detectable Input Signal Level
15.625
μ
V/PGA
=
1.953125
μ
V for PGA
8
=
=
40
μ
V/°C
(
) 8
320
μ
V/°C
=
•
=
No. of LSB/°C
320
μ
V/°C
15.625
μ
V
-------------------------
20.48 Codes/°C
=
=