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PDF LM3911 Data sheet ( Hoja de datos )
| Número de pieza | LM3911 | |
| Descripción | LM3911 Temperature Controller | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
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June 1994
LM3911 Temperature Controller
General Description
The LM3911 is a highly accurate temperature measurement
and or control system for use over a b25 C to a85 C tem-
perature range Fabricated on a single monolithic chip it
includes a temperature sensor a stable voltage reference
and an operational amplifier
The output voltage of the LM3911 is directly proportional to
temperature in degrees Kelvin at 10 mV K Using the inter-
nal op amp with external resistors any temperature scale
factor is easily obtained By connecting the op amp as a
comparator the output will switch as the temperature trans-
verses the set-point making the device useful as an on-off
temperature controller
An active shunt regulator is connected across the power
leads of the LM3911 to provide a stable 6 8V voltage refer-
ence for the sensing system This allows the use of any
power supply voltage with suitable external resistors
The input bias current is low and relatively constant with
temperature ensuring high accuracy when high source im-
pedance is used Further the output collector can be re-
turned to a voltage higher than 6 8V allowing the LM3911 to
drive lamps and relays up to a 35V supply
The LM3911 uses the difference in emitter-base voltage of
transistors operating at different current densities as the ba-
sic temperature sensitive element Since this output de-
pends only on transistor matching the same reliability and
stability as present op amps can be expected
The LM3911 is available in two package styles a metal can
TO-46 and an 8-lead epoxy mini-DIP In the epoxy package
all electrical connections are made on one side of the de-
vice allowing the other 4 leads to be used for attaching the
LM3911 to the temperature souce The LM3911 is rated for
operation over a b25 C to a85 C temperature range
Features
Y Uncalibrated accuracy g10 C
Y Internal op amp with frequency compensation
Y Linear output of 10 mV K (10 mV C)
Y Can be calibrated in degrees Kelvin Celsius or
Fahrenheit
Y Output can drive loads up to 35V
Y Internal stable voltage reference
Y Low cost
Block Diagram
Typical Applications
Ground Referred
Centigrade Thermometer
Basic Temperature Controller
Proportioning Temperature
Controller
Trims out initial zener tolerance
Set output to read C
Output goes negative on
temperature increase
RSe(Vab6 8V) kX
C1995 National Semiconductor Corporation TL H 5701
Note 1 C1 determines proportioning frequency f
Note 2 R10 e lVal a lVbl b 7V
0 0015A
Note 3 Either Vb or Va can be ground
TL H 5701 – 1
1
2R4 C1
RRD-B30M115 Printed in U S A
1 page  
Typical Applications (Continued)
Thermometer With Meter Output
R1 e (VZ) 0 01DT
IM (VZ b 0 01 TO)
2V
Select IQ s R1
R2 e 0 01 TO b IQR1
IQ
R3 e VZ b R1 b R2
IQ
J2V
IQ s R1
Meter Thermometer With Trimmed Output
Vz e Shunt regulator voltage (use 6 85)
DT e Meter temperature span ( K)
IM e Meter full scale current (A)
TO e Meter zero temperature ( K)
IQ e Current through R1 R2 R3 at zero
meter current (10 mA to 1 0 mA) (A)
Values shown for
TO e 300 K DT e 100 K
IM e 1 0 mA IQ e 100 mA
The 0 01 in the above and following equations is in units of V K or V C
and is a result of the basic 0 01V K sensitivity of the transducer
Selected as for meter thermometer except TO should
be 5 K more than desired and IQ e 100 mA
Calibrates TO
Ground Referred Thermometer
R1 e (VZ)(10mV)(DT)
VO (VZ b 0 01 TO)
RL
R2 e 0 01 TO b IQ R1
IQ
R3 e VZ b R1 b R2
IQ
Vz e Shunt regulator voltage
DT e Temperature span ( K)
TO e Temperature for zero output ( K)
VO e Full scale output voltages10V
IQ e Current through R1 R2 R3
at zero output voltage
(typically 100 mA to 1 0 mA)
Ground Referred Centigrade Thermometer
Set zero
Two Terminal Temperature to Current Transducer
J J J JVZ b 0 01 TL
IH
b
0
01 TH
R1
a
VZ b 0 01 TH
0
01 TL
R1
b
IL
R2 (X) e
(0 01
R1 R3 TH(VZ b 0 01 TL) b TL(VZ b 0 01 TH)
JVZ
R3(X) t
TH b 1
TL
IH
b
IL TH
TL
1
e
1
J(R2)(0 01 TL) a
VZ
b 0 01
R2
TL
b
IL
1
b
R4 (VZ b 0 01 TL)(R2)
%
R1
11
a
R2 R3
R2
–
TL e Temperature for IL ( K)
TH e Temperature for IH ( K)
VZ e Zener voltage (V)
IL e Low temperature output current (A)
IH e High temperature output current (A)
Values shown for IOUTe1 mA to 10 mA for 10 F to 100 F
Set temperature
TL H 5701 – 4
The 0 01 in the above and following equations is in units of V K or V C and is a result of the basic 0 01V K sensitivity of the transducer
5
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet LM3911.PDF ] | |
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