MCP9800 View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

MCP9800

2-Wire High-Accuracy Temperature Sensor

Microchip Technology 

MCP9800/1/2/3

5.3 Registers

The MCP9800/1/2/3 has four registers that are

user-accessible. These registers are specified as the

Ambient Temperature (TA) register, the Temperature

Limit-set (TSET) register, the Temperature Hysteresis

(THYST) register and device Configuration (CONFIG)

register.

The Ambient Temperature register is a read-only

register and is used to access the ambient temperature

data. The data from the ADC is loaded in parallel in the

register. The Temperature Limit-set and Temperature

Hysteresis registers are read/write registers that

provide user-programmable temperature limits. If the

ambient temperature drifts beyond the programmed

limits, the MCP9800/1/2/3 outputs an alert signal using

the ALERT pin (refer to Section 5.3.4.3 “ALERT

Output Configuration”). The device Configuration

register provides access for the user to configure the

MCP9800/1/2/3’s various features. These registers are

described in further detail in the following sections.

The registers are accessed by sending Register Point-

ers to the MCP9800/1/2/3 using the serial interface.

This is an 8-bit pointer. However, the two Least

Significant bits (LSbs) are used as pointers and all

other bits need to be cleared <0>. This device has addi-

tional registers that are reserved for test and

calibration. If these registers are accessed, the device

may not perform according to the specification. The

pointer description is shown below.

Resolution

One-Shot

Shutdown

Fault Queue

Alert Polarity

Alert Comp/Int

Configuration

Register

Temperature

Register

THYST

Register

TSET

Register

ALERT Output

Control Logic

ALERT

Output

FIGURE 5-2:

Register Block Diagram.

REGISTER 5-1: REGISTER POINTER

U-0

U-0

U-0

U-0

U-0

0

0

0

0

0

bit 7

U-0

R/W-0

R/W-0

0

P1

P0

bit 0

Legend:

R = Readable bit

-n = Value at POR

W = Writable bit

‘1’ = Bit is set

U = Unimplemented bit, read as ‘0’

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-2

bit 1-0

.

Unimplemented: Read as ‘0’

Px<1:0>: Pointer bits

00 = Temperature register (TA)

01 = Configuration register (CONFIG)

10 = Temperature Hysteresis register (THYST)

11 = Temperature Limit-set register (TSET)

DS21909D-page 14

 2010 Microchip Technology Inc.

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