lm75b-5.0-mdc National Semiconductor Corporation, lm75b-5.0-mdc Datasheet - Page 7

• Manufacturer Part Number: lm75b-5.0-mdc
• Description: Digital Temperature Sensor And Thermal Watchdog With Two-wire Interface
• Manufacturer: National Semiconductor Corporation

Typical Performance Characteristics
1.0 Functional Description
The LM75 temperature sensor incorporates a band-gap type
temperature sensor and 9-bit ADC (Delta-Sigma Analog-to-
Digital Converter). The temperature data output of the LM75
is available at all times via the I
progress, it will be stopped and restarted after the read. A
digital comparator is also incorporated that compares a se-
ries of readings, the number of which is user-selectable, to
user-programmable setpoint and hysteresis values. The
comparator trips the O.S. output line, which is programmable
for mode and polarity.
The LM75B contains all the functionality of the LM75C, plus
two additional features:
1. The LM75B has an integrated low-pass filter on both the
2. The LM75B also has a bus fault timeout feature. If the
1.1 O.S. OUTPUT, T
In Comparator mode the O.S. Output behaves like a ther-
mostat. The output becomes active when temperature ex-
ceeds the T
temperature drops below the T
SDA and the SCL line. These filters increase communi-
cations reliability in noisy environments.
SDA line is held low for longer than t
minimum to 325 ms maximum) the LM75B will reset to
the IDLE state (SDA set to high impedance) and wait for
a new start condition.
Static Quiescent Current vs Temperature
OS
limit, and leaves the active state when the
Accuracy vs Temperature
OS
AND T
HYST
2
HYST
C bus. If a conversion is in
LIMITS
limit. In this mode the
TIMEOUT
01265816
01265818
(75 ms
7
O.S. output can be used to turn a cooling fan on, initiate an
emergency system shutdown, or reduce system clock
speed. Shutdown mode does not reset O.S. state in a com-
parator mode.
In Interrupt mode exceeding T
O.S. will remain active indefinitely until reset by reading any
register via the I
by crossing T
Temperature going below T
indefinitely until being reset by a read. Placing the LM75 in
shutdown mode also resets the O.S. Output.
1.2 POWER UP AND POWER DOWN
The LM75 always powers up in a known state. The power up
default conditions are:
1. Comparator mode
2. T
3. T
4. O.S. active low
5. Pointer = “00”
If the LM75 is not connected to the I
will act as a stand-alone thermostat with the above tempera-
ture settings.
When the supply voltage is less than about 1.7V, the LM75 is
considered powered down. As the supply voltage rises
Dynamic Quiescent Current vs Temperature
OS
HYST
= 80˚C
= 75˚C
OS
, then reset, it can be activated again only by
2
C interface. Once O.S. has been activated
HYST
OS
. Again, it will remain active
also makes O.S. active but
2
C bus on power up, it
01265817
www.national.com