X60008E-41 Datasheet, PDF (8/10 Pages) Intersil Corporation – Precision 4.096V FGA Voltage Reference

X60008E-41
be reduced to about 50µVp-p using a .001µF capacitor
on the output. Noise in the 1KHz to 100KHz band can
be further reduced using a 0.1µF capacitor on the
output, but noise in the 1Hz to 100Hz band increases
due to instability of the very low power amplifier with a
0.1µF capacitance load. For load capacitances above
.001µF the noise reduction network shown in Fig. 3 is
recommended. This network reduces noise sig-
nificantly over the full bandwidth. As shown in Fig. 2,
noise is reduced to less than 40µVp-p from 1Hz to
1MHz using this network with a .01µF capacitor and a
2Kohm resistor in series with a 10µF capacitor.
Figure 2.
400
350
300
250
200
150
100
50
0
1
X60008-41 NOISE REDUCTION
CL = 0
CL = .001µF
CL = .1µF
CL = .01µF & 10µF + 2kohm
10
100
1000 10000 100000
Figure 3.
V_IN = 5.0V
.1µF
10µF
V_IN
V_O
X60008-41
GND
.01µF
2KΩ
10µF
Turn-On Time
The X60008 devices have ultra-low supply current and
thus the time to bias up internal circuitry to final values
will be longer than with higher power references. Nor-
mal turn-on time is typically 7ms. This is shown in the
graph, Figure 4. Since devices can vary in supply cur-
rent down to 300nA, turn-on time can last up to about
12ms. Care should be taken in system design to
include this delay before measurements or conver-
sions are started.
Figure 4.
6
X60008 TURN-ON TIME (25°C)
(3 Representative Units)
5
V_IN
I_IN = 700nA
4
3
I_IN = 520nA
2
I_IN = 360nA
1
0
-1
1
3
5
7
TIME (mSec)
9
11
Temperature Coefficient
The limits stated for temperature coefficient (tempco)
are governed by the method of measurement. The
overwhelming standard for specifying the temperature
drift of a reference is to measure the reference voltage
at two temperatures, take the total variation, (V_HIGH –
V_LOW), and divide by the temperature extremes of
measurement (T_HIGH – T_LOW). The result is divided by
the nominal reference voltage (at T=25°C) and multi-
plied by 10⁶ to yield ppm/°C. This is the “Box” method
for determining temperature coefficient.
REV 1.3 6/9/04
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