Datasheet

REF102
7
SBVS022B
www.ti.com
OPTIONAL NOISE REDUCTION
The high-frequency noise of the REF102 is dominated by the
zener diode noise. This noise can be greatly reduced by
connecting a capacitor between the Noise Reduction pin and
ground. The capacitor forms a low-pass filter with R
6
(refer to
the figure on page 1) and attenuates the high-frequency
noise generated by the zener. Figure 5 shows the effect of a
1µF noise reduction capacitor on the high-frequency noise of
the REF102. R
6
is typically 7kΩ so the filter has a –3dB
frequency of about 22Hz. The result is a reduction in noise
from about 800µV
PP
to under 200µV
PP
. If further noise
reduction is required, use the circuit in Figure 14.
APPLICATIONS INFORMATION
High accuracy, extremely low drift, outstanding stability, and
low cost make the REF102 an ideal choice for all instrumen-
tation and system reference applications. Figures 6 through
14 show a variety of useful application circuits.
6
b) Precision –10V Reference.
a) Resistor Biased –10V Reference
R
S
I
L
4
REF102
2
−10V Out
See SBVA008 for more detail.
V+ (1.4V to 26V)
1.4mA < < 5.4mA
(5V −I
L
)
R
S
2
6
4
10V
OPA227
R
1
2kΩ
C
1000pF
1
−10V Out
−15V
REF102
V+ (1.4V to 26V)
FIGURE 6. –10V Reference Using a) Resistor or b) OPA227.
NO C
N
C
N
= 1µF
FIGURE 5. Effect of 1µF Noise Reduction Capacitor on
Broadband Noise (f
–3dB
= 1MHz)