SP2526 Datasheet, PDF (8/18 Pages) Sipex Corporation – +3.0V to +5.5V USB Power Control Switch

tively, a 1ms debounce routine may be pro-
grammed into the USB logic controller, elimi-
nating the need for the RC filter.
Soft Start Condition
The soft start feature of the SP2526 is imple-
mented by holding the output turn-on rise time
to 1ms. When off, the device has high imped-
ance MOSFET channels that slowly become
low impedance as the device powers on. This
prevents an inrush current from causing voltage
drops that result from charging a capacitive
load and can pull the USB voltage bus below
specified levels. This satisfies the USB voltage
droop requirements for bus-powered applica-
tions. Refer to the circuit in Figure 6.
The SP2526 can provide inrush current limiting
for applications with large load capacitances
where C_BULK > 10µF. Refer to the circuit in
Figure 7 for a configuration that will meet USB
transient regulation specifications with large
load capacitances.
Enable Input
The ENA and ENB control pins must be driven
to a logic high or logic low for a clearly defined
signal input. Floating these control lines may
cause unpredictable operation.
USB Compliance
The SP2526 is ideal for self-powered and bus-
powered Universal Serial Bus (USB) applica-
tions. A USB port provides a +5.0V bus and
ground return line in addition to a twisted pair
for data.
The SP2526 will comply with the following
USB requirements:
1) The fault current is well below the UL 25VA
safety requirements;
2) The Flag Outputs are available to indicate
fault conditions to USB controllers;
3) The MOSFET switches' low on-resistance
meets USB voltage drop requirements;
4) Each MOSFET switch channel can supply
500mA as required by USB downstream devices;
5) Soft start eliminates any momentary voltage
drops on the upstream port that may occur when
the switches are enabled in bus-powered applica-
tions.
Refer to Table 1 for a USB compliance summary
of the SP2526. Additional features include the
following:
6) An Undervoltage Lockout ensures that the
device remains off unless there is a valid input
supply voltage present;
7) +3.3V and +5.0V logic compatible enable
inputs;
8) Thermal Shutdown prevents the possiblity of
catastrophic switch failure from high-current
loads;
8) The device is available in both active-high and
active-low versions.
Refer to Figures 8 to 26 for typical performance
characteristics of the SP2526.
Rev. 8/21/01
SP2526 +3.0V to +5.5V USB Power Control Switch
8
© Copyright 2001 Sipex Corporation