LM73CIMK-0/NOPB National Semiconductor, LM73CIMK-0/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM73CIMK-0/NOPB
• Description: DIGITAL TS W/SMBUS INTERFACE
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM73CIMK-0/NOPB

• Function: Temp Monitoring System (Sensor)
• Topology: ADC (Sigma Delta), Comparator, Register Bank
• Sensor Type: Internal
• Sensing Temperature: -40°C ~ 150°C
• Output Type: I²C™/SMBus™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: TSOT-23-6, TSOT-6
• For Use With: LM73EVAL - BOARD EVALUATION FOR LM73
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM73CIMK-0; LM73CIMK-0TR

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1.0 Functional Description
The LM73 is a digital temperature sensor that senses the
temperature of its die using a sigma-delta analog-to-digital
converter and stores the temperature in the Temperature
Register. The LM73's 2-wire serial interface is compatible with
SMBus 2.0 and I
for a detailed description of the differences between the I
bus and SMBus.
The temperature resolution is programmable, allowing the
host system to select the optimal configuration between sen-
sitivity and conversion time. The LM73 can be placed in
shutdown to minimize power consumption when temperature
data is not required. While in shutdown, a 1-shot conversion
mode allows system control of the conversion rate for ultimate
flexibility.
The LM73 features the following registers. See Section 2.0
for a complete list of the pointer address, content, and reset
state of each register.
1.
2.
3.
4.
5.
6.
7.
1.1 POWER-ON RESET
The power-on reset (POR) state is the point at which the sup-
ply voltage rises above the power-on reset threshold (speci-
fied in the electrical specifications table), generating an
internal reset. Each of the registers contains a defined value
upon POR and this data remains there until any of the follow-
ing occurs:
1. The first temperature conversion is completed, causing the
Temperature Register and various status bits to be updated
internally, depending on the value of the measured tempera-
ture.
2. The master writes different data to any Read/Write (R/W)
bits, or
3. The LM73 is powered down.
1.2 ONE-SHOT CONVERSION
The LM73 features a one-shot conversion bit, which is used
to initiate a single conversion and comparison cycle when the
LM73 is in shutdown mode. While the LM73 is in shutdown
mode, writing a "1" to the One-Shot bit in the Configuration
Register will cause the LM73 to perform a single temperature
conversion and update the Temperature Register and the af-
fected status bits. Operating the LM73 in this one-shot mode
allows for extremely low average-power consumption, mak-
ing it ideal for low-power applications.
When the One-Shot bit is set, the LM73 initiates a tempera-
ture conversion. After this initiation, but before the completion
of the conversion and resultant register updates, the LM73 is
in a "one-shot" state. During this state, the Data Available
(DAV) flag in the Control/Status register is "0" and the Tem-
Pointer Register
Temperature Register
Configuration Register
T
T
Control/Status Register
Identification Register
HIGH
LOW
Register
Register
2
C. Please see the SMBus 2.0 specification
2
C
8
perature Register contains the value 8000h (-256°C). All other
registers contain the data that was present before initiating
the one-shot conversion. After the temperature measurement
is complete, the DAV flag will be set to "1" and the temperature
register will contain the resultant measured temperature.
1.3 TEMPERATURE DATA FORMAT
The resolution of the temperature data and the size of the data
word are user-selectable through bits RES1 and RES0 in the
Control/Status Register. By default, the LM73 temperature
stores the measured temperature in an 11-bit (10 bits plus
sign) word with one least significant bit (LSB) equal to 0.25°
C. The maximum word size is 14 bits (13-bits plus sign) with
a resolution of 0.03125 °C/LSB.
The temperature data is reported in 2's complement format.
The word is stored in the 16-bit Temperature Register and is
left justified in this register. Unused temperature-data bits are
always reported as "0".
Temperature
Temperature
RES1
CONTROL BIT
+0.125°C
−0.125°C
0
0
1
1
+0.25°C
−0.25°C
+150°C
+150°C
+25°C
−25°C
−40°C
+25°C
−25°C
−40°C
+1°C
−1°C
+1°C
−1°C
0°C
0°C
RES0
0
1
0
1
11-bit (10-bit plus Sign)
12-bit (11-bit plus Sign)
0100 1011 0000 0000
0000 1100 1000 0000
0000 0000 1000 0000
0000 0000 0010 0000
0000 0000 0000 0000
1111 1111 1110 0000
1111 1111 1000 0000
1111 0011 1000 0000
1110 1100 0000 0000
0100 1011 0000 0000
0000 1100 1000 0000
0000 0000 1000 0000
0000 0000 0001 0000
0000 0000 0000 0000
1111 1111 1111 0000
1111 1111 1000 0000
1111 0011 1000 0000
1110 1100 0000 0000
WORD SIZE
11 bits
12 bits
13 bits
14 bits
Binary
Binary
Digital Output
Digital Output
DATA FORMAT
0.03125 °C/LSB
0.0625 °C/LSB
RESOLUTION
0.125 °C/LSB
0.25 °C/LSB
0C80h
FFE0h
EC00h
0C80h
EC00h
4B00h
FF80h
F380h
4B00h
FFF0h
FF80h
F380h
0080h
0020h
0000h
0080h
0010h
0000h
Hex
Hex