REF02
U1
15V
V
IN
V+
U2
27V TO 55V
2
V
IN
V
O
REF02
V
IN
TEMP
V
OUT
TRIM
00375-F-018
V
O
6
15V
V
TEMP
1.9mV/°C
OP1177
V–
GND
REF02
TRIM
GND
4
2
V
IN
V
O
6
10V
5
10kΩ
Figure 19. Temperature Monitoring
REF02
V+ (12V TO 32V)
2
TRIM
GND
V
O
6
4
5
10kΩ
5V
R7
27kΩ
2
V
IN
V
O
HEATING
ELEMENT
R1
(9.2kΩ)
R3
(1.3kΩ)
R2
1.5kΩ
R6
2
+
V
IN
REF02
CMP02
V–
4
1
8
V+
7
TRIM
GND
4
00375-F-020
6
3
5
REF02
TEMP
GND
(SEE NOTE 1) 4
10kΩ
R
B
6.8kΩ
3 –
Figure 21. Reference Stack
R5
2.2kΩ
R4
2.7kΩ
PRECISION CURRENT SOURCE
A current source with 35 V output compliance and excellent
output impedance can be obtained using this circuit. REF02
keeps the line voltage and power dissipation constant in device;
the only important error consideration at room temperature is
the negative supply rejection of the op amp. The typical 3 µV/V
PSRR of the OP02E will create a 20 ppm change (3 µV/V ×
35 V/5 V) in output current over a 25 V range. For example, a
5 mA current source can be built (R = 1 kΩ) with 350 MΩ
output impedance.
+50V
35V
R
O
=
20
×
10
–6
×
5mA
6
V
O
2
V
IN
Figure 20. Temperature Controller
REFERENCE STACK WITH EXCELLENT LINE
REGULATION
Two REF01s and one REF02 can be stacked to yield 5.000 V,
15.000 V, and 25.000 V outputs. An additional advantage is
near-perfect line regulation of the 5.0 V and 15.0 V output. A 27
V to 55 V input change produces an output change that is less
than the noise voltage of the devices. A load bypass resistor
(RB) provides a path for the supply current (I
SY
) of the 15.000 V
regulator.
In general, any number of REF01s and REF02s can be stacked
this way. For example, 10 devices will yield 10 outputs in 5 V or
10 V steps. The line voltage can change from 100 V to 130 V.
However, care must be taken to ensure that the total load
currents do not exceed the maximum usable current (typically
21 mA).
00375-F-019
NOTES
1. REF02 SHOULD BE THERMALLY CONNECTED
TO SUBSTANCE BEING HEATED.
2. NUMBERS IN PARENTHESES ARE FOR A
SETPOINT TEMPERATURE OF 60°C.
3. R3 = R1
||
R2
||
R6
REF02
2
2
V
IN
V
O
6
GND
4
REF02
1
GND
4
C
7
6
R
C
R
(TRIM FOR
CALIBRATION)
2
3
V
O
= 0V
TO 25V
OP02E
4
I
O
=
–5V
5V
R
Figure 22. Precision Current Source
Rev. F | Page 11 of 16
00375-F-021
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