XRP2525 Datasheet, PDF (9/11 Pages) Exar Corporation – Single/Dual Channel USB 3.0 Power Distribution Switch

XRP2525 - XRP2526
Single/Dual Channel USB 3.0 Power Distribution Switch
THEORY OF OPERATION
The XRP2525 and XRP2526 devices are
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.
INPUT & OUTPUT
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.
ERROR FLAG
The error flag signal (FLG_X output pin) is an
open-drain output and is pulled low (active
low) upon detection of the following
conditions:
 Over-current condition
 Over-temperature condition
 Under voltage lockout condition
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 until all fault conditions have been
removed and is independent for each
individual channel.
CURRENT LIMIT
The current limit threshold is preset internally.
It protects the output MOSFET switches from
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.
UNDER-VOLTAGE LOCKOUT
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 of an input voltage below
approximately 1.68V, the power switch is
turned off while a fault condition is reported by
the error flag signal.
THERMAL PROTECTION
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.
TEST CIRCUIT
© 2011 Exar Corporation
9/11
Rev. 1.1.0