LM76CNMX-3 National Semiconductor, LM76CNMX-3 Datasheet - Page 6

• Manufacturer Part Number: LM76CNMX-3
• Description: 0.5C/ 1C/ 12-Bit Sign Digital Temperature Sensor and Thermal Window Comparator with Two-Wire Interface
• Manufacturer: National Semiconductor

www.national.com
Logic Electrical Characteristics
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 2: When the input voltage (V
maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5 mA to four.
Note 3: See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National Semicon-
ductor Linear Data Book for other methods of soldering surface mount devices.
Note 4: Human body model, 100 pF discharged through a 1.5 k
Note 5: LM76
Note 6: While the LM76 has a full-scale-range in excess of 128˚C, prolonged operation at temperatures above 125˚C is not recommended.
Note 7: The LM76 will operate properly over the +V
specified for rated accuracy at the nominal supply voltage of 3.3V. Accuracy of the LM76CNM-3 will degrade 0.2˚C for a
The LM76CHM-5 is tested and specified for a rated accuracy at the nominal supply voltage of 5.0V. Accuracy of the LM76CHM-5 will degrade 0.08˚C for a
variation in +V
Note 8: Typicals are at T
Note 9: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 10: 12 bits + sign, two’s complement
Note 11: This specification is provided only to indicate how often temperature data is updated. The LM76 can be read at any time without regard to conversion state
(and will yield last conversion result). If a conversion is in process it will be interrupted and restarted after the end of the read.
Note 12: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy with internal heating. This can cause an error of 0.64˚C at full
rated sink current and saturation voltage based on junction-to-ambient thermal resistance.
Note 13: Hysteresis value adds to the T
subtracts from the T
discussion of the function of hysteresis refer to Section 1.1 , TEMPERATURE COMPARISON, and Figure 3 .
Note 14: Default values set at power up.
Electrical Characteristics
Continued
1.0 Functional Description
The LM76 temperature sensor incorporates a band-gap type
temperature sensor, 13-bit ADC, and a digital comparator
with user-programmable upper and lower limit values. The
comparator activates either the INT line for temperatures
outside the T
for temperatures which exceed T_CRIT. The lines are pro-
grammable for mode and polarity.
S
JA
from the nominal value.
LOW
(thermal resistance, junction-to-ambient) when attached to a printed circuit board with 2 oz. foil is 200˚C/W.
HIGH
and T
and T_CRIT setpoints (e.g.: if T
A
FIGURE 2. Temperature-to-Digital Transfer Function (Non-linear scale for clarity)
= 25˚C and represent most likely parametric norm.
HIGH
I
) at any pin exceeds the power supplies (V
window, or the T_CRIT_A line
LOW
setpoint value (e.g.: if T
S
supply voltage range of 3V to 5.5V for the LM76CNM-3 and the LM76CHM-5. The LM76CNM-3 is tested and
HIGH
setpoint = 64˚C, and hysteresis = 2˚C, then actual hysteresis point is 64−2 = 62˚C). For a detailed
resistor. Machine model, 200 pF discharged directly into each pin.
(Continued)
LOW
setpoint = 10˚C, and hysteresis = 2˚C, then actual hysteresis point is 10+2 = 12˚C); and
I
<
6
GND or V
1.1 TEMPERATURE COMPARISON
LM76 provides a window comparison against a lower (T
and upper (T
(T_CRIT) functions as a critical alarm shutdown. Figure 3
depicts the comparison function as well as the modes of op-
eration.
1.1.1 STATUS BITS
The internal Status bits operate as follows:
I
>
+V
S
) the current at that pin should be limited to 5 mA. The 20 mA
HIGH
) trip point. A second upper trip point
±
DS101015-5
1% variation in +V
S
from the nominal value.
LOW
±
1%
)