NSC LM77CIM-5, LM77CIM-3 Datasheet
LM77
9-Bit + Sign Digital Temperature Sensor and Thermal
Window Comparator with Two-Wire Interface
June 1999
LM77 9-Bit + Sign Digital Temperature Sensor and Thermal Window Comparator with Two-Wire
Interface
General Description
The LM77 is a digital temperature sensor and thermal window comparator with an I
window-comparator architecture of the LM77 eases the design of temperature control systems conforming to the ACPI
(Advanced Configuration and Power Interface) specification
for personal computers. The open-drain Interrupt (INT) output becomes active whenever temperature goes outside a
programmable window, while a separate Critical Temperature Alarm (T_CRIT_A) output becomes active when the
temperature exceeds a programmable critical limit. The INT
output can operate in either a comparator or event mode,
while the T_CRIT_A output operates in comparator mode
only.
The host can program both the upper and lower limits of the
window as well as the critical temperature limit. Programmable hysterisis as well as a fault queue are available to
minimize false tripping. Two pins (A0, A1) are available for
address selection.Thesensor powers up with default thresholds of 2˚C T
T_CRIT.
The LM77’s 3.0V to 5.5V supply voltage range, Serial Bus interface, 9-bit + sign output, and full-scale range of over
128˚C make it ideal for a wide range of applications. These
include thermal management and protection applications in
personal computers, electronic test equipment, office electronics, automotive, and HVAC applications.
HYST
2
C™Serial Bus interface. The
, 10˚C T
LOW
, 64˚C T
, and 80˚C
HIGH
Simplified Block Diagram
Features
n Window comparison simplifies design of ACPI
compatible temperature monitoring and control.
n Serial Bus interface
n Separate open-drain outputs for Interrupt and Critical
Temperature shutdown
n Shutdown mode to minimize power consumption
n Up to 4 LM77s can be connected to a single bus
n 9-bit + sign output; full-scale reading of over 128˚C
Key Specifications
n Supply Voltage 3.0V to 5.5V
n Supply Current operating 250 µA (typ)
500 µA (max)
shutdown 5 µA (typ)
n Temperature
Accuracy
−10˚C to 65˚C
−25˚C to 100˚C
−55˚C to 125˚C
±
1.5˚C(max)
±
2˚C(max)
±
3˚C(max)
Applications
n System Thermal Management
n Personal Computers
n Office Electronics
n Electronic Test Equipment
n Automotive
n HVAC
DS100136-1
I2C®is a registered trademark of Philips Corporation.
© 1999 National Semiconductor Corporation DS100136 www.national.com
Connection Diagram
Ordering Information
Order Number Supply Voltage Supplied As
LM77CIM-3 3.3V
LM77CIMX-3 3.3V 2500 Units on Tape and Reel
LM77CIM-5 5V
LM77CIMX-5 5V 2500 Units on Tape and Reel
Pin Description
SO-8
DS100136-2
LM77 See NS Package Number M08A
Label Pin
SDA 1 Serial Bi-Directional Data Line. Open Drain Output From Controller
SCL 2 Serial Bus Clock Input From Controller
T_CRIT_A 3 Critical Temperature Alarm Open Drain Output Pull Up Resistor, Controller Interrupt Line
GND 4 Power Supply Ground Ground
INT 5 Interrupt Open Drain Output Pull Up Resistor, Controller Interrupt Line
+V
S
A0–A1 7,6 User-Set Address Inputs Ground (Low, “0”) or +V
#
8 Positive Supply Voltage Input DC Voltage from 3V to 5.5V
Function Typical Connection
or System Hardware Shutdown
S
DS100136-3
FIGURE 1. Typical Application
(High, “1”)
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Absolute Maximum Ratings (Note 1)
Supply Voltage −0.3V to 6.5V
Voltage at any Pin −0.3V to (+V
Input Current at any Pin 5 mA
Package Input Current (Note 2) 20 mA
T_CRIT_A and INT Output Sink
Current 10 mA
T_CRIT_A and INT Output
Voltage 6.5V
Storage Temperature −65˚C to +125˚C
+ 0.3V )
S
Soldering Information, Lead
Temperature
SOP and MSOP Package (Note 3)
Vapor Phase (60 seconds) 215˚C
Infrared (15 seconds) 220˚C
ESD Susceptibility (Note 4)
Human Body Model 2500V
Machine Model 250V
Operating Ratings (Notes 1, 5)
Specified Temperature Range T
(Note 6) −55˚C to +125˚C
Supply Voltage Range (+V
)(Note 7) +3.0V to +5.5V
S
Temperature-to-Digital Converter Characteristics
=
Unless otherwise noted, these specifications apply for +V
LM77CIM-3 (Note 7). Boldface limits apply for T
noted.
A
Parameter Conditions
=
Accuracy T
−10˚C to +65˚C
A
=
−25˚C to +100˚C
A
=
T
−55˚C to +125˚C
A
S
=
=
T
J
±
10%for LM77CIM-5 and +V
+5 Vdc
to T
T
MIN
; all other limits T
MAX
Typical
(Note 8)
Resolution (Note 10) 10
0.5
Temperature Conversion Time (Note 11) 70 125 ms
Quiescent Current I
2
C Inactive 0.25 mA
2
I
C Active 0.25 0.5 mA (max)
Shutdown Mode 5 10 µA
T
Default Temperature (Notes 13, 14) 2 ˚C
HYST
T
Default Temperature (Note 14) 10 ˚C
LOW
T
Default Temperature (Note 14) 64 ˚C
HIGH
T
Default Temperature (Note 14) 80 ˚C
C
=
+3.3 Vdc
S
=
=
T
+25˚C, unless otherwise
A
J
Limits
(Note 9)
±
1.5
±
2.0
±
3.0
±
10%for
Units
(Limit)
˚C (max)T
Bits
˚C
MIN
to T
MAX
Logic Electrical Characteristics
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
=
and +V
unless otherwise noted.
+3.3 Vdc
S
±
10%for LM77CIM-3. Boldface limits apply for T
Symbol Parameter Conditions
V
V
V
V
I
I
C
IN(1)
IN(0)
IN(1)
IN(0)
IN(1)
IN(0)
IN
SDA and SCL Logical “1” Input
Voltage
SDA and SCL Logical “0” Input
Voltage
A0 and A1 Logical “1” Input
Voltage
A0 and A1 Logical “0” Input
Voltage
Logical “1” Input Current V
Logical “0” Input Current V
=
+V
IN
=
0V −0.005 −1.0 µA (max)
IN
Capacitance of All Digital Inputs 20 pF
S
=
=
T
J
Typical
(Note 8)
MIN
to T
T
A
0.005 1.0 µA (max)
=
±
10%for LM77CIM-5
+5 Vdc
S
; all other limits T
MAX
Limits
(Note 9)
+VSx 0.7 V (min)
+V
+0.3 V (max)
S
−0.3 V (min)
+V
x 0.3 V (max)
S
2.0 V (min)
+V
+0.3 V (max)
S
−0.3 V (min)
0.8 V (max)
=
=
T
+25˚C,
A
J
Units
(Limit)
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Logic Electrical Characteristics (Continued)
DIGITAL DC CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
=
and +V
unless otherwise noted.
+3.3 Vdc
S
±
10%for LM77CIM-3. Boldface limits apply for T
Symbol Parameter Conditions
I
OH
V
OL
High Level Output Current V
Low Level Output Voltage I
T_CRIT_A Output Saturation
Voltage
=
+V
OH
=
3mA 0.4 V (max)
OL
=
I
4.0 mA
OUT
(Note 12)
T_CRIT_A Delay 1 Conversions
t
OF
Output Fall Time C
=
400 pF 250 ns (max)
L
=
I
3mA
O
S
=
=
T
J
Typical
(Note 8)
MIN
to T
T
A
=
+5 Vdc
S
; all other limits T
MAX
Limits
(Note 9)
10 µA (max)
0.8 V (max)
±
10%for LM77CIM-5
=
=
T
+25˚C,
A
J
Units
(Limit)
(max)
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Logic Electrical Characteristics (Continued)
SERIAL BUS DIGITAL SWITCHING CHARACTERISTICS Unless otherwise noted, these specifications apply for +V
±
10%for LM77CIM-5, +V
Vdc
wise specified. Boldface limits apply for T
The switching characteristics of the LM77 fully meet or exceed the published specifications of the I
rameters are the timing relationship between SCL and SDA signal related to the LM77. They are not the I2C bus specifications.
Symbol Parameter Conditions
t
1
t
2
t
3
t
4
t
5
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: SeeAN-450 “Surface Mounting Methods and Their Effect on Product Reliability” or the section titled “Surface Mount” found in a current National Semiconductor Linear Data Book for other methods of soldering surface mount devices.
Note 4: Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine model, 200 pF discharged directly into each pin.
Note 5: LM77 θ
Note 6: While the LM77 has a full-scale-range in excess of 128˚C, prolonged operation at temperatures above 125˚C is not recommended.
Note 7: Both part numbers of the LM77 will operate properly over the +V
curacy at their nominal supply voltage. Accuracy will typically degrade 1˚C/V of variation in +V
Note 8: Typicals are at T
Note 9: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).
Note 10: 9 bits + sign, two’s complement
Note 11: Thisspecification is provided only to indicate how often temperature data is updated. The LM77 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
Note 14: Default values set at power up.
SCL (Clock) Period 2.5 µs(min)
Data in Set-Up Time to SCL High 100 ns(min)
Data Out Stable after SCL Low 0 ns(min)
SDA Low Set-Up Time to SCL Low (Start Condition) 100 ns(min)
SDA High Hold Time after SCL High (Stop Condition) 100 ns(min)
(thermal resistance, junction-to-ambient) when attached to a printed circuit board with 2 oz. foil is 200˚C/W.
JA
A
and T_CRIT setpoints (e.g.: if T
HIGH
=
+3.3 Vdc
S
) at any pin exceeds the power supplies (V
I
=
25˚C and represent most likely parametric norm.
LOW
±
10%for LM77CIM-3, CL (load capacitance) on output lines=80 pF unless other-
=
=
T
A
setpoint value (e.g.: if T
HIGH
Section 1.1
, TEMPERATURE COMPARISON, and
to T
T
J
MIN
LOW
setpoint=64˚C, and hysteresis=2˚C, then actual hysteresis point is 64−2=62˚C). For a detailed
=
; all other limits T
MAX
<
I
supply voltage range of 3V to 5.5V . The devices are tested and specified for rated ac-
S
setpoint=10˚C, and hysteresis=2˚C, then actual hysteresis point is 10+2=12˚C); and
GND or V
>
+VS) the current at that pin should be limited to 5 mA. The 20 mA
I
as it varies from the nominal value.
S
Figure 3
=
T
+25˚C, unless otherwise noted.
A
J
.
2
C bus. The following pa-
Typical
(Note 8)
DS100136-4
Limits
(Note 9)
S
=
+5
Units
(Limit)
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