LM80CIMT-3 National Semiconductor, LM80CIMT-3 Datasheet - Page 15

• Manufacturer Part Number: LM80CIMT-3
• Manufacturer: National Semiconductor

Specifications of LM80CIMT-3

• Watchdog Timer: Yes
• Chip Enable Signals: No
• Package Type: TSSOP
• Operating Supply Voltage (min): 2.8V
• Operating Supply Voltage (max): 5.75V
• Operating Temp Range: -25C to 125C
• Operating Temperature Classification: Commercial
• Power Fail Detection: No
• Mounting: Surface Mount
• Pin Count: 24
• Battery Backup Switching: No
• Manual Reset: No
• Lead Free Status / RoHS Status: Not Compliant

Divide by 1
Divide by 2
Divide by 4
Divide by 8
Mode Select
Counts are based on 2 pulses per revolution tachometer out-
puts.
7.0 TEMPERATURE MEASUREMENT SYSTEM
The LM80 bandgap type temperature sensor and ADC per-
form 9-bit or a 12-bit two's-complement conversions of the
(Non-Linear Scale for Clarity)
RPM
4400
3080
2640
Nominal RPM
8800
4400
2200
1100
Time per Revolution
13.64 ms
19.48 ms
22.73 ms
FIGURE 8. 9-bit Temperature-to-Digital Transfer Function
Time per Revolution
13.64 ms
27.27 ms
54.54 ms
6.82 ms
Given Speed in Decimal
15
Counts for “Divide by 2”
Counts for the
temperature. An 8-bit digital comparator is also incorporated
that compares the readings to the user-programmable Hot
and Overtemperature setpoints, and Hysteresis values.
(Default) in Decimal
(maximum counts)
153
153
153
153
153 counts
219 counts
255 counts
70% RPM
10004020
6160
3080
1540
770
Time per Revolution
Typical RPM
for 70% RPM
Comments
70% RPM
60% RPM
19.48 ms
38.96 ms
77.92 ms
9.74 ms
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