X60008B-25 Datasheet, PDF (8/10 Pages) Intersil Corporation – Precision 2.5V FGA Voltage Reference

X60008B-25
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 2kΩ resistor in series with a 10µF
capacitor.
Figure 2.
400
350
300
250
200
150
100
50
0
1
X60008-25 NOISE REDUCTION
CL = 0
CL = .001µF
CL = .1µF
CL = .01µF & 10µF + 2kΩ
10
100
1000 10000 100000
Figure 3.
V_IN = 6.5V
.1µF
10µF
V_IN
V_O
X60008-25
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.
X60008 TURN-ON TIME (25°C)
6
V_IN
5
4
690 nA
3
V_OUT
2
520 nA
1
320 nA
0
-1
1
3
5
7
9
TIME (mSec)
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.
8
FN8140.0
March 15, 2005