LM32 National Semiconductor Corporation, LM32 Datasheet - Page 17

• Manufacturer Part Number: LM32
• Description: Dual Thermal Diode Temperature Sensor With SensorPath™ Bus
• Manufacturer: National Semiconductor Corporation

000 101
2.0 Register Set
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.
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 LM32. The
FuncDescriptor value of this function is ‘0001’.
2.9.1 Operation
The Temperature Measurement function as implemented in the LM32 supports 3 temperature zones, the LM32’s internal
temperature (LM32’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.
The minimum scan rate is recommended to be 4Hz (i.e. the measurement data is updated at least once in 250 ms), see Section
2.10 for further details. In Low-Power Mode, the scan rate is four times lower than the scan rate in Active Mode. The scan rate
effects the bus bandwidth required to read the results. The sampling rate of the temperature measurements can also be controlled
via the Conversion Rate register, see Section 2.10 for further details.
Data Readout
register clears the Status Function 1 flag (SF1). The result is available in the Readout register waiting for the master to read it
during the master sensor read sequence. If a new result is ready before the previous result has been read, the new result
overwrites the previous result and the Error Function 1 flag (ERF1) is set (indicating an overrun event). Reading the Readout
Reg
Add
15-5
Bit
0
1
2
3
4
Register
Name
Device
Control
Type
R/W Reset (Device Reset). When set to "1" this bit initiates a Device Reset operation ( See Section 2.2). This bit
R/W Shutdown (Shutdown Mode). When set to "1" this bit stops the operation of all functions and places the
R/W LowPwr (Low-Power Mode). When set to "1" this bit slows the operation of all functions and places the
R/W EnF1 (Enable Function 1). When bit is set to "1" this bit Function 1 is enabled for operation. A function may
RO
RO
self-clears after the Device Reset operation is completed.
0: Normal device operation. (default)
1: Device Reset
The LM32 does not require a Device Reset command after power.
device in the lowest power consumption mode.
0: Device in Active Mode. (default)
1: Device in Shutdown Mode.
device in a low power consumption mode. In Low-Power Mode, the conversion rate of the LM32 is effected
see Section 2.10 for further details.
0: Device in Active Mode. (default)
1: Device in Low-Power Mode.
Not supported. Will always read "0".
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.
Not supported. Will always read "0".
When a new result is stored in the Readout register a Function Event is generated. Reading the Readout
R/
R/
W
W
Val
(Continued)
0h
O
P
R
MSb
Bit
15
0
Bit
14
0
Bit
13
0
Bit
12
0
Bit
11
0
Reserved
17
Description
Bit
10
0
Bit9
0
Bit
8
0
Bit
7
0
Bit
6
0
Bit
5
0
EnF1 Res
Bit
4
Bit
3
Low
Pwr
Bit
2
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down
Shut
Bit
1
LSb
Bit
Re
set
0