ISL21080-EVALZ Intersil, ISL21080-EVALZ Datasheet - Page 16

• Manufacturer Part Number: ISL21080-EVALZ
• Description: EVAL BOARD FOR ISL21080
• Manufacturer: Intersil

Specifications of ISL21080-EVALZ

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Noise Performance and Reduction
The output noise voltage in a 0.1Hz to 10Hz bandwidth is
typically 30µV
Performance Characteristics Curves” which begin on
page 10. The noise measurement is made with a
bandpass filter made of a 1 pole high-pass filter with a
corner frequency at 0.1Hz and a 2-pole low-pass filter
with a corner frequency at 12.6Hz to create a filter with a
9.9Hz bandwidth. Noise in the 10kHz to 1MHz bandwidth
is approximately 400µV
output, as shown in Figure 39. These noise
measurements are made with a 2 decade bandpass filter
made of a 1-pole high-pass filter with a corner frequency
at 1/10 of the center frequency and 1-pole low-pass filter
with a corner frequency at 10 times the center frequency.
Figure 39 also shows the noise in the 10kHz to 1MHz
band can be reduced to about 50µV
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
0.001µF, the noise reduction network shown in Figure 40
is recommended. This network reduces noise
significantly over the full bandwidth. As shown in
Figure 39, noise is reduced to less than 40µV
1Hz to 1MHz using this network with a 0.01µF capacitor
and a 2kΩ resistor in series with a 10µF capacitor.
FIGURE 38. ISL21080 USED AS A LOW COST
0.01µF
PRECISION CURRENT SOURCE
P-P
V
ISL21080-1.5
OUT
. This is shown in the plot in the “Typical
GND
V
+8V TO 28V
IN
= 1.5V
V
~150.3µA
I
IL AT 0.1% ACCURACY
SY
OUT
P-P
~ 0.31µA
16
Z
with no capacitance on the
OUT
> 100MΩ
P-P
I
using a 0.001µF
I
SET =
L
I
= I
SET
R
10kΩ
0.1%
10ppm/°C
SET
V
R
SET +
P-P
OUT
SET
from
IR
SET
ISL21080
Turn-On Time
The ISL21080 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. Normal
turn-on time is typically 7ms. This is shown in Figure 38.
Since devices can vary in supply current 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 conversions are started.
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
V
measurement (T
the nominal reference voltage (at T = +25°C) and
multiplied by 10
method for specifying temperature coefficient.
V
LOW
IN
= 3.0V
400
350
300
250
200
150
100
0.1µF
), and divide by the temperature extremes of
50
FIGURE 40. NOISE REDUCTION NETWORK
0
1
FIGURE 39. NOISE REDUCTION
10µF
6
CL = 0
CL = 0.001µF
CL = 0.1µF
CL = 0.01µF AND 10µF + 2kΩ
HIGH
10
to yield ppm/°C. This is the “Box”
– T
ISL21080
100
LOW
GND
V
IN
). The result is divided by
V
O
1k
0.01µF
10k
May 25, 2010
HIGH
FN6934.4
100k
10µF
2kΩ
-