X60008A-50 Datasheet, PDF (8/11 Pages) Intersil Corporation – 1ppm/C, 5.0V, Precision Low-Power FGA Voltage Reference

X60008A-50
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
X60008-50 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
X60008-50
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.
X60008-50 TURN-ON TIME (25°C)
7
6
5
4
I_IN = 730nA
I_IN = 500nA
3
I_IN = 320nA
2
1
0
-1 1 3 5 7 9 11 13 15
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
multiplied by 10⁶ to yield ppm/°C. This is the “Box”
method for determining temperature coefficient.
8
FN8139.0
March 15, 2005