REF02
OUTPUT ADJUSTMENT
The REF02 trim terminal can be used to adjust the output
voltage over a 5 V ±300 mV range. This feature lets the system
designer trim system errors by setting the reference to a voltage
other than 5 V. The output also can be set to exactly 5.000 V or
to 5.12 V for binary applications.
+5V
2
6
R1
5.6kΩ
V
REF
15V
2
V
IN
V
O
6
V
O
+
+2.5V
REF02
R2
5.6kΩ
6
7
2
3
00375-F-016
4
–
+
OP02
4
V
O
+ =
OUTPUT
R
1
R
2
), V
O
– =
)
(V
(V
R
1
+ R
2 REF
R
1
+ R
2 REF
+V
O
–2.5V
–9V
REF02
3
TEMP
TRIM
5
10kΩ
00375-F-013
Figure 17. ±2.5 V Reference
GND
4
TEMPERATURE MONITORING
As described previously, the REF02 provides a TEMP output
(Pin 3) that varies linearly with temperature. This output can be
used to monitor the temperature change in the system. The
voltage at V
TEMP
is approximately 550 mV at 25°C, and the
temperature coefficient is approximately 1.96 mV/°C (see
Figure 14. Output Adjustment Circuit
Adjustment of the output does not significantly
affect the
temperature performance of the device. The temperature
coefficient change is approximately 0.7 ppm/°C for 100 m
V of
output adjustment.
850
+18V
2
800
750
TEMP PIN OUTPUT (mV)
V
IN
= 9V
SAMPLE SIZE = 6
V
IN
Z PACKAGE AND 833 PRODUCT
700
650
600
550
J, S, AND P PACKAGES
500
450
00375-F-017
REF02
GND
4
–18V
00375-F-014
∆
V
TEMP
/
∆
T = 2.1mV/°C
∆
V
TEMP
/
∆
T = 1.96mV/°C
Figure 15. Burn-In Circuit
+15V
2
V
IN
V
O
6
10kΩ
5
10kΩ
+15V
–5V
5kΩ
+5V
400
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
Figure 18. Voltage at TEMP Pin vs. Temperature
REF02
3
TEMP TRIM
GND
4
0.1µF
A voltage change of 39.2 mV at the TEMP pin corresponds to a
20°C change in temperature.
The TEMP function is provided as a convenience rather than a
precise feature. Since the voltage at the TEMP node is acquired
from the band gap core, current pulling from this pin will have
a significant effect on V
OUT
. Care must be taken to buffer the
TEMP output with a suitable low bias current op amp, such as
the AD8601, AD820, or OP1177 (all of which would result in
less than a 100 V change in ΔV
OUT
) See Figure 19. Without
buffering, even tens of microamps drawn from the TEMP pin
can cause V
OUT
to fall out of specification.
OP02
00375-F-015
–15V
Figure 16. ±5 V Reference
Rev. F | Page 10 of 16
AD [ ANALOG DEVICES ]
