ISL60002BIH310Z-T7A Просмотр технического описания (PDF) - Renesas Electronics
Номер в каталоге
Компоненты Описание
производитель
ISL60002BIH310Z-T7A Datasheet PDF : 40 Pages
| |||
ISL60002
Board Assembly Considerations
FGA references provide high accuracy and low temperature drift
but some PC board assembly precautions are necessary. Normal
output voltage shifts of 100µV to 1mV can be expected with
Pb-free reflow profiles. Avoid excessive heat or extended
exposure to high reflow or wave solder temperatures. This may
reduce device initial accuracy.
Post-assembly X-ray inspection may also lead to permanent
changes in device output voltage and should be minimized or
avoided. If X-ray inspection is required, it is advisable to monitor
the reference output voltage to verify excessive shift has not
occurred. If large amounts of shift are observed, it is best to add
an X-ray shield consisting of thin zinc (300µm) sheeting to allow
clear imaging, yet block X-ray energy that affects the FGA
reference.
Special Applications Considerations
In addition to post-assembly examination, there are also other
X-ray sources that may affect the FGA reference long term
accuracy. Airport screening machines contain X-rays and will
have a cumulative effect on the voltage reference output
accuracy. Carry-on luggage screening uses low level X-rays and is
not a major source of output voltage shift, however, if a product is
expected to pass through that type of screening over 100 times,
it may need to consider shielding with copper or aluminum.
Checked luggage X-rays are higher intensity and can cause
output voltage shift in much fewer passes, thus devices expected
to go through those machines should definitely consider
shielding. Note that just two layers of 1/2 ounce copper planes
will reduce the received dose by over 90%. The leadframe for the
device which is on the bottom also provides similar shielding.
If a device is expected to pass through luggage X-ray machines
numerous times, it is advised to mount a 2-layer (minimum) PC
board on the top, and along with a ground plane underneath will
effectively shield it from 50 to 100 passes through the machine.
Since these machines vary in X-ray dose delivered, it is difficult to
produce an accurate maximum pass recommendation.
Noise Performance and Reduction
The output noise voltage in a 0.1Hz to 10Hz bandwidth is
typically 30µVP-P. Noise in the 10kHz to 1MHz bandwidth is
approximately 400µVP-P with no capacitance on the output, as
shown in Figure 117. 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 117 also shows the noise in the 10kHz to 1MHz
band can be reduced to about 50µVP-P using a 0.001µF
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 0.001µF the noise reduction network shown
in Figure 118 is recommended. This network reduces noise
significantly over the full bandwidth. As shown in Figure 117,
noise is reduced to less than 40µVP-P from 1Hz to 1MHz using
this network with a 0.01µF capacitor and a 2kΩ resistor in series
with a 10µF capacitor.
400
350
300
250
200
150
100
50
01
CL = 0
CL = 0.001µF
CL = 0.1µF
CL = 0.01µF AND 10µF + 2kΩ
10
100
1k
10k
NOISE FREQUENCY (Hz)
FIGURE 117. NOISE REDUCTION
100k
VIN = 3.0V
0.1µF
10µF
VIN
VO
ISL60002-25
VOUT = 2.50V
GND
0.01µF
2kΩ
10µF
FIGURE 118. NOISE REDUCTION NETWORK
FN8082 Rev 22.00
Mar 9, 2018
Page 35 of 40
Share Link: 