MCP9800A0-M/MS MICROCHIP [Microchip Technology], MCP9800A0-M/MS Datasheet - Page 13

• Manufacturer Part Number: MCP9800A0-M/MS
• Description: 2-Wire High-Accuracy Temperature Sensor
• Manufacturer: MICROCHIP [Microchip Technology]

5.0
The MCP9800/1/2/3 temperature sensor consists of a
band-gap type temperature sensor, a  Analog-to-
Digital Converter (ADC), user-programmable registers
and a 2-wire I
FIGURE 5-1:
 2010 Microchip Technology Inc.
Register
Pointer
FUNCTIONAL DESCRIPTION
Configuration
Temperature
2
Register
Register
Register
Register
C protocol-compatible serial interface.
T
T
HYST
SET
Alert Comp/Int
Fault Queue
Alert Polarity
Resolution
Functional Block Diagram.
Shutdown
One-Shot
Interface
I
2
C™
Temperature
Band-Gap
0.0625°C
 ADC
0.125°C
Sensor
0.25°C
0.5°C
5.1
The MCP9800/1/2/3 uses the difference in the base-
emitter voltage of a transistor while its collector current
is changed from IC
depends only on the ratio of the two currents and the
ambient temperature, as shown in
EQUATION 5-1:
5.2
A Sigma-Delta ADC is used to convert V
word that corresponds to the transistor temperature.
The converter has an adjustable resolution from 0.5°C
(at 30 ms conversion time) to 0.0625°C (at 240 ms
conversion time). Thus, it allows the user to make
trade-offs between resolution and conversion time.
Refer
Register (CONFIG)”
Resolution”
Where:
IC
1
and IC
to
Temperature Sensor
 Analog-to-Digital Converter
V
Section 5.3.2 “Sensor
BE

for details.
T = temperature in kelvin
q = electron charge
k = Boltzmann's constant
2
V
MCP9800/1/2/3
BE
= change in diode base-emitter
= currents with n:1 ratio
1
=
voltage
to IC


and
kT
----- -
q
2


. With this method, the V

Section 5.3.4.7 “ ADC
ln IC

1
Equation

DS21909C-page 13
IC
2
Configuration

BE
5-1.
to a digital
BE