XRP2526 Exar Corporation, XRP2526 Datasheet - Page 9

• Manufacturer Part Number: XRP2526
• Description: Respectively Single And Dual Channel Integrated High-side Power Distribution Switches
• Manufacturer: Exar Corporation

THEORY OF OPERATION
The
respectively single and dual channel integrated
high-side power distribution switches that can
be used in any self or bus powered USB
applications. They are compliant with the
latest USB 3.0 specifications. The reverse
current protection feature prevents current to
flow from OUT to IN when the device is
disabled.
I
Placing bulk capacitances of at least 47μF and
10μF at the input and output pins respectively
reduces power supply transients under heavy
current load conditions.
It is important to place a 1μF ceramic bypass
capacitor from IN to GND as close as possible
to the device in order to control supply
transients.
Furthermore, bypassing the output pin with a
0.1μF to 1μF ceramic capacitor improves the
device response to short-circuit transients.
E
The error flag signal (FLG
open-drain output and is pulled low (active
low)
conditions:
Over-temperature and under voltage lockout
conditions are flagged immediately while the
over – current condition is reported only if this
condition persists continuously for longer than
the blanking time of 10ms. The blanking time
prevents erroneous reporting of current faults
due to brief output current spikes.
Once activated, the error flag signal remains
low
removed
individual channel.
C
The current limit threshold is preset internally.
It protects the output MOSFET switches from
© 2011 Exar Corporation
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XRP2525
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damages resulting from undesirable short
circuit conditions or excess inrush current,
which is often encountered during hot plug-in.
The low limit of the current limit threshold of
the XRP2525 and XRP2526 allows a minimum
current of 0.9A through the MOSFET switches.
When an overcurrent condition is detected, the
output current is limited to a constant current
limit threshold value and output voltage is
reduced accordingly. Triggering the current
limit function is signaled by the Error Flag
after 10ms of blanking time period.
U
Under-voltage lockout function (UVLO) keeps
the internal power switch from being turned
on until the power supply has reached at least
1.68V, even if the switch is enabled. Upon
detection
approximately 1.68V, the power switch is
turned off while a fault condition is reported by
the error flag signal.
T
Internal thermal sensing circuitry monitors the
operating temperature of the device for each
channel independently. Upon detection of a
temperature in excess of 135°C, the power
switch for the given channel is disabled
preventing any damages to the device while a
fault condition is reported by the error flag
signal. A built-in 10°C hysteresis allows the
device to cool down to 125°C before resuming
normal operations on the faulty channel at
which point the error flag signal is cleared.
T
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