STMicroelectronics LM234D Three terminal adjustable current source Datasheet

LM134-LM234-LM334
Three terminal adjustable current sources
Features
■
Operates from 1V to 40V
■
0.02%/V current regulation
■
Programmable from 1µA to 10mA
■
±3% initial accuracy
Z
TO-92
(Plastic package)
Description
The LM134/LM234/LM334 are 3-terminal
adjustable current sources characterized by:
■
an operating current range of 10000: 1
■
an excellent current regulation
■
a wide dynamic voltage range of 1V t 10V
D
SO-8
(Plastic micropackage)
The current is determined by an external resistor
without requiring other external components.
Pin connections
Reverse voltages of up to 20V will only draw a
current of several microamperes. This enables the
circuit to operate as a rectifier and as a source of
current in a.c. applications.
TO-92
(Bottom view)
For the LM134/LM234/LM334, the voltage on the
control pin is 64mV at +25°C and is directly
proportional to the absolute temperature (°K). The
simplest external resistor connection generates a
current with approximately 0.33%/°C temperature
dependence. Zero drift can be obtained by adding
an additional resistor and a diode to the external
circuit.
May 2007
v+
2
v-
ADJ
1
3
SO-8
(Top view)
Rev 3
NC
8
NC
7
V6
NC
5
1
ADJ
2
NC
3
NC
4
V+
1/16
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16
Schematic diagram
1
Schematic diagram
Figure 1.
2
LM134-LM234-LM334
Schematic diagram
Absolute maximum ratings
Table 1.
Absolute maximum ratings
Symbol
Parameter
LM134
Voltage V+ to VForward
Reverse
VADJ-
2/16
LM234
40
20
LM334
Unit
30
20
V
ADJ pin to V- voltage
5
V
Iset
Set current
10
mA
Ptot
Power dissipation
400
mW
Tstg
Storage temperature range
-65 to +150
°C
Toper
Operating free-air temperature range
-55 to +125
-25 to +100
0 to +70
°C
LM134-LM234-LM334
3
Electrical characteristics
Electrical characteristics
Tj = +25°C with pulse testing so that junction temperature does not change during testing
(unless otherwise specified)
Table 2.
Electrical characteristics
LM134 - LM234
LM334
Parameter
Unit
Min.
Typ.
Set current error (V+ = +2.5V) -(1)
10µA ≤ Iset ≤ 1mA
1mA ≤ Iset ≤ 5mA
2µA ≤ Iset ≤ 10µA
Ratio of set current to V- current
10µA ≤ Iset ≤ 1mA
1mA ≤ Iset ≤ 5mA
2µA ≤ Iset ≤ 10µA
14
Typ.
18
14
14
23
0.02
0.01
14
T
18
14
14
0.05
0.03
0.02
0.01
%
26
0.8
0.9
1
0.03
0.02
0.96 T
Max.
6
8
12
0.8
0.9
1
Average change in set current with input voltage
2µA ≤ Iset ≤ 1mA
+1.5V ≤ V+ ≤ +5V
+5V ≤ V+ ≤ +40V
1mA ≤ Iset ≤ 5mA
+1.5V ≤ V+ ≤ +5V
+5V ≤ V+ ≤ +40V
Effective shunt capacitance
Min.
3
5
8
Minimum operating voltage
2µA ≤ Iset ≤ 100µA
100µA ≤ Iset ≤ 1mA
1mA ≤ Iset ≤ 5mA
Temperature dependence of set current - (2)
25µA ≤ Iset ≤ 1mA
Max.
V
0.1
0.05
%/V
0.03
0.02
1.04 T 0.96 T
15
T
15
1.04 T
pF
1. The set current is the current flowing into the V+ pin. It is determined by the following formula:
Iset = 67.7mV/Rset (Tj = +25°C)
The set current error is expressed as a percent deviation from this amount.
2. Iset is directly proportional to absolute temperature (°K). Iset at any temperature can be calculated from
Iset = Io (T/To)
where Io is Iset measured at To (°K).
3/16
Electrical characteristics
Output impedance
Figure 3.
Frequency (Hz)
Figure 4.
Startup
Iset (µA)
Figure 5.
Time (scale changes at each current level)
Transient response
Time (scale changes at each current level)
Figure 7.
Current noise
Current (pA/√Hz)
Voltage across Rset
Voltage (mV)
Figure 6.
Temperature (°C)
4/16
Maximum slew rate for linear
operation
Slew rate (V/µs)
Impedance (Ohm)
Figure 2.
LM134-LM234-LM334
Frequency (Hz)
LM134-LM234-LM334
Turn-on voltage
Figure 9.
Ratio of Iset to V- current
Ratio
Iset (mA)
Figure 8.
Electrical characteristics
V+ to V- voltage (V)
Iset (mA)
5/16
Application information
4
Application information
4.1
Slew rate
LM134-LM234-LM334
At slew rates above a threshold (see Figure 4 and Figure 5), the LM134, LM234, LM334 can
have a non-linear current characteristic. The slew rate at which this takes place is directly
proportional to Iset. At Iset = 10µA, dv/dt max. = 0.01V/µs ; at Iset = 1mA, dv/dt max. = 1V/µs.
Slew rates of more than 1V/µs do not damage the circuit nor do they produce high currents.
4.2
Thermal effects
Internal heating can have a significant effect on current regulation for an Iset above 100µA.
For example, each increase of 1V in the voltage across the LM134 at Iset = 1mA will
increase the junction temperature by ≈ 0.4°C (in still air). The output current (Iset) has a
temperature coefficient of about 0.33%/°C. Thus the change in current due to the increase
in temperature will be (0.4) (0.33) = 0.132%. This is a degradation of 10 : 1 in regulation
versus the true electrical effects. Thermal effects should be taken into account when d.c.
regulation is critical and Iset is higher than 100µA.
4.3
Shunt capacitance
In certain applications, the 15pF value for the shunt capacitance should be reduced:
●
because of loading problems,
●
because of limitation of output impedance of the current source in a.c. applications.
You can easily reduce the capacitance by adding a FET as shown in Typical applications on
page 8.
The value of this capacitance can be reduced by at least 3pF and regulation can be
improved by an order of magnitude without any modifications of the d.c. characteristics
(except for the minimum input voltage).
4.4
Noise
The current noise produced by LM134, LM234, and LM334 is about 4 times that of a
transistor. If the LM134, LM234, LM334 is used as an active load for a transistor amplifier,
the noise at the input will increase by about 12dB. In most cases this is acceptable, and a
single amplifier can be built with a voltage gain higher than 2000.
4.5
Lead resistance
The sense voltage which determines the current of the LM134, LM234, LM334 is less than
100mV. At this level, the thermocouple effects and the connection resistance should be
reduced by locating the current setting resistor close to the device. Do not use sockets for
the ICs. A contact resistance of 0.7Ω is sufficient to decrease the output current by 1% at the
1mA level.
6/16
LM134-LM234-LM334
4.6
Application information
Sensing temperature
The LM134, LM234, LM334 are excellent remote controlled temperature sensors because
their operation as current sources preserves their accuracy even in the case of long
connecting wires. The output current is directly proportional to the absolute temperature in
Kelvin degrees according to the following equation.
( 227µV/°K) (T )
I set = ----------------------------------------R set
The calibration of the LM134, LM234, LM334 is simplified by the fact that most of the initial
accuracy is due to gain limitation (slope error) and not an offset. Gain adjustment is a one
point trim because the output of the device extrapolates to zero at 0°K.
Figure 10. Device calibration
This particularity of the LM134, LM234, LM334 is illustrated in the above diagram. Line abc
represents the sensor current before adjustment and line a’b’c’ represents the desired
output. A gain adjustment provided at T2 will move the output from b to b’ and will correct
the slope at the same time so that the output at T1 and T3 will be correct. This gain
adjustment can be carried out by means of Rset or the load resistor used in the circuit. After
adjustment, the slope error should be less than 1%. A low temperature coefficient for Rset is
necessary to keep this accuracy. A 33ppm/°C temperature drift of Rset will give an error of
1% on the slope because the resistance follows the same temperature variations as the
LM134, LM234, LM334.
Three wires are required to isolate Rset from the LM134, LM234, LM334. Since this solution
is not recommended, metal-film resistors with a drift of less than 20ppm/°C are now
available. Wirewound resistors can be used when very high stability is required.
7/16
Application information
LM134-LM234-LM334
Typical applications
Figure 11. Basic 2-terminal current source
Figure 12. Alternate trimming technique
Figure 13. Terminating remote sensor for
voltage output
Figure 14. Zero temperature coefficient
current source
8/16
LM134-LM234-LM334
Application information
Figure 15. Low output impedance
thermometer
Figure 16. Low output impedance
thermometer
Figure 17. Micropower bias
Figure 18. Low input voltage reference driver
9/16
Application information
Figure 19. In-line current limiter
10/16
LM134-LM234-LM334
Figure 20. Fet cascading for low capacitance
LM134-LM234-LM334
5
Package information
Package information
In order to meet environmental requirements, STMicroelectronics offers these devices in
ECOPACK® packages. These packages have a lead-free second level interconnect. The
category of second level interconnect is marked on the package and on the inner box label,
in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics
trademark. ECOPACK specifications are available at: www.st.com.
11/16
Package information
5.1
LM134-LM234-LM334
SO-8 package mechanical data
Dimensions
Ref.
Millimeters
Min.
Typ.
A
Max.
Min.
Typ.
1.75
0.25
Max.
0.069
A1
0.10
A2
1.25
b
0.28
0.48
0.011
0.019
c
0.17
0.23
0.007
0.010
D
4.80
4.90
5.00
0.189
0.193
0.197
H
5.80
6.00
6.20
0.228
0.236
0.244
E1
3.80
3.90
4.00
0.150
0.154
0.157
e
0.004
0.010
0.049
1.27
0.050
h
0.25
0.50
0.010
0.020
L
0.40
1.27
0.016
0.050
k
1°
8°
1°
8°
ccc
12/16
Inches
0.10
0.004
LM134-LM234-LM334
TO-92 ammopack and tape & reel package mechanical data
A1
P
T
P
A
H
W2
W0
W
L1
W1
H0
H
I1
d
H1
5.2
Package information
D0
F1 F2
P2
P0
Millimeters
Inches
Dim.
Min.
Typ.
Max.
Min.
Typ.
Max.
AL
5.0
0.197
A
5.0
0.197
T
4.0
0.157
d
0.45
0.018
I1
2.5
0.098
P
11.7
12.7
13.7
0.461
0.500
0.539
PO
12.4
12.7
13
0.488
0.500
0.512
P2
5.95
6.35
6.75
0.234
0.250
0.266
F1/F2
2.4
2.5
2.8
0.094
0.098
0.110
Δh
-1
0
1
-0.039
0
0.039
ΔP
-1
0
1
-0.039
0
0.039
W
17.5
18.0
19.0
0.689
0.709
0.748
W0
5.7
6
6.3
0.224
0.236
0.248
W1
8.5
9
9.75
0.335
0.354
0.384
W2
0.5
0.020
H
20
0.787
H0
15.5
16
H1
DO
L1
16.5
0.610
0.630
25
3.8
4.0
4.2
11
0.650
0.984
0.150
0.157
0.165
0.433
13/16
Package information
5.3
LM134-LM234-LM334
TO-92 bulk package mechanical data
Millimeters
Inches
Dim.
Min.
L
14/16
Typ.
Max.
Min.
1.27
Typ.
Max.
0.05
B
3.2
3.7
4.2
0.126
0.1457
0.1654
O1
4.45
5.00
5.2
0.1752
0.1969
0.2047
C
4.58
5.03
5.33
0.1803
0.198
0.2098
K
12.7
O2
0.407
0.0197
0.02
a
0.35
0.5
0.5
0.508
0.016
0.0138
LM134-LM234-LM334
6
Ordering information
Ordering information
Table 3.
Order codes
Temperature
range
Package
Packing
Marking
LM134D/DT
-55°C to +125°C
SO-8
Tube or
Tape & reel
LM134
LM134Z/ZT/AP
-55°C to +125°C
TO-92
Bulk or
Tape & reel or
Ammopack
LM134
LM234D/DT
-25°C to +100°C
SO-8
Tube or
Tape & reel
LM234
LM234Z/ZT/AP
-24°C to +100°C
TO-92
Bulk or
Tape & reel or
Ammopack
LM234
LM334D/DT
-0°C to +70°C
SO-8
Tube or
Tape & reel
LM334
LM334Z/ZT/AP
-0°C to +70°C
TO-92
Bulk or
Tape & reel or
Ammopack
LM334
LM334AD/ADT
-0°C to +70°C
SO-8
Tube or
Tape & reel
LM334A
LM334AZ/AZT/AAP
-0°C to +70°C
TO-92
Bulk or
Tape & reel or
Ammopack
LM334A
Part number
7
Revision history
Date
Revision
2-May-2003
1
Initial release.
28-Oct-2005
2
Internal revision.
3
Corrected error in pinout diagram for TO-92 package on cover page
(it is a bottom view, not a top view).
Updated Section 5: Package information and expanded Table 3:
Order codes.
29-May-2007
Changes
15/16
LM134-LM234-LM334
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