SP2526A Datasheet, PDF (4/10 Pages) Sipex Corporation – Dual USB High-Side Power Switch

Error Flag
An open-drained output of an N-channel
MOSFET, the FLG output is pulled low to
signal the following fault conditions: input
undervoltage, output current limit, and thermal
shutdown.
Current Limit
The current limit threshold is preset internally.
It protects the output MOSFET switches from
damage 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
SP2526A allows a minimum current of 0.6A
through the MOSFET switches. A current limit
condition will signal the error flag.
Thermal Shutdown
When the chip temperature exceeds 135ºC for
any reason other than overcurrent fault of either
one of the two MOSFETs, the thermal shut-
down function turns off both MOSFET switches
and signals the error flag. A hysteresis of 10ºC
prevents the MOSFETs from turning back on
until the chip temperature drops below 125ºC.
However, if thermal shutdown is triggered by
chip temperature rise resulting from overcurrent
fault condition of either one of the MOSFET
switches, the thermal shutdown function will
only turn off the switch that is in overcurrent
condition and the other switch can still remain
its normal operation. In other words, the ther-
mal shutdown function of the two switches is
independent of each other in the case of
overcurrent fault.
APPLICATION INFORMATION
Supply Filtering
A 0.1µF to 1µF bypass capacitor from IN to
GND, located near the device, is strongly recom-
mended to control supply transients. Without a
bypass capacitor, an output short may cause
sufficient ringing on the input (from supply lead
inductance) to damage internal control circuitry.
Transient Requirements
USB supports dynamic attachment (hot plug-in)
of peripherals. A current surge is caused by the
input capacitance of downstream device. Ferrite
beads are recommended in series with all power
and ground connector pins. Ferrite beads reduce
EMI and limit the inrush current during hot-
attachment by filtering high-frequency signals.
Short Circuit Transient
Bulk capacitance provides the short-term tran-
sient current needed during a hot-attachment event.
A 33 µF,16V tantalum or a 100µF,10V electro-
lytic capacitor mounted close to downstream con-
nector each port should provide transient drop
protection
Printed Circuit Layout
The Power circuitry of USB printed circuit boards
requires a customized layout to maximize ther-
mal dissipation and to minimize voltage drop and
EMI.
Date: 12/06/04
SP2526A Dual USB High-Side Power Switch
4
© Copyright 2004 Sipex Corporation