June 1999
LM61
2.7V, SOT-23 or TO-92 Temperature Sensor
General Description
Applications
n Cellular Phones
n Computers
n Power Supply Modules
n Battery Management
n FAX Machines
n Printers
n HVAC
n Disk Drives
n Appliances
The LM61 is a precision integrated-circuit temperature sen-
sor that can sense a −30˚C to +100˚C temperature range
while operating from a single +2.7V supply. The LM61’s out-
put voltage is linearly proportional to Celsius (Centigrade)
temperature (+10 mV/˚C) and has a DC offset of +600 mV.
The offset allows reading negative temperatures without the
need for a negative supply. The nominal output voltage of the
LM61 ranges from +300 mV to +1600 mV for a −30˚C to
+100˚C temperature range. The LM61 is calibrated to pro-
±
±
vide accuracies of 2.0˚C at room temperature and 3˚C
over the full −25˚C to +85˚C temperature range.
Key Specifications
The LM61’s linear output, +600 mV offset, and factory cali-
bration simplify external circuitry required in a single supply
environment where reading negative temperatures is re-
quired. Because the LM61’s quiescent current is less than
125 µA, self-heating is limited to a very low 0.2˚C in still air.
Shutdown capability for the LM61 is intrinsic because its in-
herent low power consumption allows it to be powered di-
rectly from the output of many logic gates.
±
±
n Accuracy at 25˚C
2.0 or 3.0˚C
(max)
±
±
n Accuracy for −30˚C to +100˚C
n Accuracy for −25˚C to +85˚C
n Temperature Slope
4.0˚C (max)
3.0˚C (max)
+10 mV/˚C
n Power Supply Voltage Range
+2.7V to +10V
125 µA (max)
@
n Current Drain 25˚C
Features
n Calibrated linear scale factor of +10 mV/˚C
n Rated for full −30˚ to +100˚C range
n Suitable for remote applications
±
n Nonlinearity
0.8˚C (max)
n Output Impedance
800 Ω (max)
Typical Application
DS012897-2
=
VO (+10 mV/˚C x T ˚C) + 600 mV
Temperature (T)
+100˚C
+85˚C
Typical VO
+1600 mV
+1450 mV
+850 mV
+600 mV
+350 mV
+300 mV
+25˚C
0˚C
−25˚C
−30˚C
FIGURE 1. Full-Range Centigrade Temperature Sensor (−30˚C to +100˚C)
Operating from a Single Li-Ion Battery Cell
© 1999 National Semiconductor Corporation
DS012897
www.national.com