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.
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.
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.
Pin connections
TO-92
(Bottom view)
v+
2
ADJ
1
v-
3
SO-8
(Top view)
NC
8
NC
7
V-
6
NC
5
1
ADJ
2
NC
3
NC
4
V+
May 2007
Rev 3
1/16
www.st.com
16
LM134-LM234-LM334
Electrical characteristics
3
Electrical characteristics
T
j
= +25°C with pulse testing so that junction temperature does not change during testing
(unless otherwise specified)
Table 2.
Electrical characteristics
LM134 - LM234
Parameter
Min.
Typ.
Max.
Min.
Typ.
Max.
LM334
Unit
Set current error (V
+
= +2.5V) -
(1)
10µA
≤
I
set
≤
1mA
1mA
≤
I
set
≤
5mA
2µA
≤
I
set
≤
10µA
Ratio of set current to V
-
current
10µA
≤
I
set
≤
1mA
1mA
≤
I
set
≤
5mA
2µA
≤
I
set
≤
10µA
Minimum operating voltage
2µA
≤
I
set
≤
100µA
100µA
≤
I
set
≤
1mA
1mA
≤
I
set
≤
5mA
Average change in set current with input voltage
2µA
≤
I
set
≤
1mA
+1.5V
≤
V
+
≤
+5V
+5V
≤
V
+
≤
+40V
1mA
≤
I
set
≤
5mA
+1.5V
≤
V
+
≤
+5V
+5V
≤
V
+
≤
+40V
Temperature dependence of set current -
(2)
25µA
≤
I
set
≤
1mA
Effective shunt capacitance
0.96 T
14
18
14
14
0.8
0.9
1
3
5
8
23
14
18
14
14
0.8
0.9
1
6
8
12
26
%
V
0.02
0.01
0.03
0.02
T
15
0.05
0.03
0.02
0.01
0.03
0.02
0.1
0.05
%/V
1.04 T 0.96 T
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:
I
set
= 67.7mV/R
set
(T
j
= +25°C)
The set current error is expressed as a percent deviation from this amount.
2. I
set
is directly proportional to absolute temperature (°K). I
set
at any temperature can be calculated from
I
set
= I
o
(T/T
o
)
where I
o
is I
set
measured at To (°K).
3/16
Electrical characteristics
LM134-LM234-LM334
Figure 2.
Output impedance
Figure 3.
Maximum slew rate for linear
operation
Impedance (Ohm)
Frequency (Hz)
Figure 4.
Startup
Figure 5.
Slew rate (V/µs)
I
set
(µA)
Transient response
Time (scale changes at each current level)
Figure 6.
Voltage across R
set
Time (scale changes at each current level)
Figure 7.
Current noise
Current (pA/√
Hz)
Voltage (mV)
Temperature (°C)
Frequency (Hz)
4/16
PCB Design
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