Bit

Type

Description

7RO

BER (Bus Error) This bit is set when the device either generates, or receives an error indication in the ACK

bit of the transaction (i.e., no-acknowledge). BER is cleared by Device Reset or by reading the Device Status

register.

0: No transaction error occurred.

1: An ACK bit error (no-acknowledge) occurred during the last transaction.

2.8 DEVICE CONTROL (Addr: 000 101; 05h)

This register responds to a broadcast write command (Device Number 000). Write using broadcast address is ignored by bits

15-2. This register is set to the reset value by a Device Reset.

Reg

Add

Register

Name

R/

W

P

O

R

Val

Bit

15

MSb

Bit

14

Bit

13

Bit

12

Bit

11

Bit

10

Bit9

Bit

8

Bit

7

Bit

6

Bit

5

Bit

4

Bit

3

Bit

2

Bit

1

Bit

0

LSb

000 101

Device

Control

R/

W

0h

Reserved

EnF2 EnF1 Res

Low

Pwr

Shut

down

Re

set

0000000000

Bit

Type

Description

0

R/W

Reset (Device Reset). When set to "1" this bit initiates a Device Reset operation ( See Section 2.2). This bit

self-clears after the Device Reset operation is completed.

0: Normal device operation. (default)

1: Device Reset

The LM40 does not require a Device Reset command after power.

1

R/W

Shutdown (Shutdown Mode). When set to "1" this bit stops the operation of all functions and places the

device in the lowest power consumption mode.

0: Device in Active Mode. (default)

1: Device in Shutdown Mode.

2

R/W

LowPwr (Low-Power Mode). When set to "1" this bit slows the operation of all functions and places the

device in a low power consumption mode. In Low-Power Mode, the conversion rate of the LM40 is effected

see Section 2.11 for further details.

0: Device in Active Mode. (default)

1: Device in Low-Power Mode.

3RO

Not supported. Will always read "0".

4

R/W

EnF1 (Enable Function 1). When bit is set to "1" this bit Function 1 is enabled for operation. A function may

require setup before this bit is set. The function registers can be accessed even when the function is

disabled.

0: Function 1 is disabled. (default)

1: Function is enabled.

5

R/W

EnF2 (Enable Function 2). Same as EnF1 for Function 2.

15-6

RO

Not supported. Will always read "0".

2.9 TEMPERATURE MEASUREMENT FUNCTION (TYPE - 0001)

This section defines the register structure and operation of a Temperature Measurement function as it applies to the LM40. The

FuncDescriptor value of this function is ‘0001’.

2.9.1 Operation

The Temperature Measurement function as implemented in the LM40 supports 3 temperature zones, the LM40’s internal

temperature (LM40’s junction temperature) and the remote temperature of 2 thermal diodes (stand alone transistors or integrated

in chips). The function measures multiple temperature points and reports the readout to the master. The measurement of all the

enabled temperature sensors is cyclic and continuous.

Sensor Scan

The Control register of the function defines which temperature sensors are included in the scan. A sensor is

scanned only if it is enabled by the Sensor Enable bits (EN0, EN1, and EN2). The sensors are scanned in an ascending,

round-robin order, based on the sensor number. Disabled sensors are skipped and the next enabled sensor in ascending order

is scanned.

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