7237

NTE7237
Integrated Circuit
3−Terminal Adjustable Current Source
TO−92 Type Package
Description:
The NTE7237 is a 3−terminal adjustable current source in a TO−92 type package featuring 10,000:1
range in operating current, excellent current regulation and a wide dynamic voltage range of 1V to
40V. Current is established with one external resistor and no other parts are required. Initial current
accuracy is 3%. This device is a true floating current source with no separate power supply connections. In addition, reverse applied voltages of up to 20V will draw only a few dozen microamperes of
current, allowing the device to act as both a rectifier and current source in AC applications.
The sense voltage used to establish operating current in the NTE7237 is 64mV at +25C and is directly
proportional to absolute temperature (K). The simplest one external resistor connection, then, generates
a current with [ +0.33%/C temperature dependence. Zero drift operation can be obtained by adding
one extra resistor and a diode.
Applications for the current sources include bias networks, surge protection, low power reference,
ramp generation, LED driver, and temperature sensing.
The NTE7237 is guaranteed over a temperature range of 0 to +70C.
Features:
D Operates From 1V to 40V
D 0.02%/V Current Regulation
D Programmable from 1A to 10mA
D True 2−Terminal Operation
D 3% Initial Accuracy
Absolute Maximum Ratings:
V+ to V− Forward Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V
V+ to V− Reverse Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V
R Pin to V− Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5V
Set Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10mA
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400mW
ESD Susceptibility (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000V
Operating Temperature Range (Note 2), Topr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to +70C
Thermal Resistance, Junction−to−Ambient, RthJA
0.4” Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180C/W
0.125” Leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160C/W
Lead Temperature (During Soldering, 10sec), TL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +260C
Note 1. Human body model, 100pF discharge through a 1.5k resistor.
Note 2. For elevated temperature operation, TJmax is +100C.
Electrical Characteristics: (Note 3)
Parameter
Test Conditions
Set Current Error
Min
Typ
Max
Unit
10A  ISET  1mA
−
−
6
%
1mA  ISET  5mA
−
−
8
%
2A  ISET  10A
−
−
12
%
100A  ISET  1mA
14
18
26
1mA  ISET  5mA
−
14
−
2A  ISET  100A
−
18
26
2A  ISET  100A
−
0.8
−
V
100A  ISET  1mA
−
0.9
−
V
1mA  ISET  5mA
−
1.0
−
V
1.5V  V+  5V
−
0.02
0.1
%/V
5V  V+  40V
−
0.01
0.05
%/V
1mA  ISET  5mA 1.5V  V+  5V
−
0.03
−
%/V
5V  V+  40V
−
0.02
−
%/V
0.96T
T
1.04T
−
15
−
V+ = 2.5V, Note 4
Ratio of Set Current to Bias Current
Minimum Operating Voltage
2A  ISET  1mA
Average Change in Set Current
with Input Voltage
Temperature Dependence of Set Current
25A  ISET  1mA, Note 5
Effective Shunt Capacitance
pF
Note 3. Unless otherwise specified, tests are performed at TJ = +25C with pulse testing so that junction
temperature does not change during test.
Note 4. Set current is the current flowing into the V+ pin. For the Basic 2−Terminal Current Source
circuit, ISET is determined by the following formula: ISET = 67.7mV/RSET (@ +25C). Set current error is expressed as a percent deviation from this amount. ISET increases at 0.336%/C at
TJ = +25C (227V/C)
Note 5. 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).
Basic 2−Terminal Current Source
+VIN
ISET
V+
R
V−
IBIAS
ISET
−VIN
VR
RSET
.135 (3.45) Min
.210
(5.33)
Max
Seating Plane
.021 (.445) Dia Max
.500
(12.7)
Min
V−
V+
R
.100 (2.54)
.050 (1.27)
.165
(4.2)
Max
.105 (2.67) Max
.205 (5.2) Max
.105 (2.67) Max