SI8513-C-IS Datasheet, PDF (12/37 Pages) List of Unclassifed Manufacturers – Si85XX UNIDIRECTIONAL AC CURRENT SENSORS

Si85xx
1.0%
0.5%
0.0%
-0.5%
-1.0%
-1.5%
-2.0%
-2.5%
-3.0%
-3.5%
0
25
50
75
100
125
Temperature (Celcius)
Current Sense
Transformer
Si8502
Figure 6. Differential Temperature
Calibration Error
Figure 7 shows the Si85xx thermal characteristics of the
on-chip sense resistance over the temperature range of
–40 to +125 °C. Series inductance is constant at 2 nH
(max) across this same temperature range.
Figure 8. Leading-Edge Noise Suppression
Waveforms (200 kHz, 9.3 A Load)
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-20
0
20
40
60
80
Temperature (°C)
100 120
Figure 7. Series Resistance Thermal
Characteristics
2.6. Leading Edge Noise Suppression
High-amplitude spikes on the leading edge of the
primary switching waveforms can cause the PWM latch
to be erroneously reset at the start of the switching cycle
when operating in current mode control. To prevent this
problem, leading edge blanking is commonly used to
disable the current comparator during the early portion
of the primary-side switching cycle. The Si85xx
eliminates leading-edge noise spikes by including them
in the signal integration. As shown in the output
waveform of Figure 8 (Si8502 waveform measured
directly on OUT pin with no external filter), noise present
in the input waveform is eliminated without the use of
blanking.
2.7. FAULT Output
The FAULT output (Si8517/8/9) guards against Si85xx
output signal errors caused by missing reset cycles.
FAULT is asserted when a measurement cycle exceeds
the internal watchdog timer times limit of t_WD. FAULT
can be used to alert a local microcontroller or digital
power controller of a current sense failure or to initiate a
system shutdown. To detect faults, tie a 200 k resistor
from TRST/FAULT to VDD.
2.8. Safe Operating Limits
The Si85xx is a very robust current sensor. Its maximum
input current rate of change is limited to 1000 A/µs. The
maximum peak ac input current limit is 200 A. The
thermal limit or continuous dc current flow limit is 30 A.
Exceeding these limits may cause long-term reliability
issues. Refer to “AN329: Extending the Full-Scale
Range of the Si85xx” for more information.
12
Preliminary Rev. 0.4