SP2526 datasheet(8/18 Pages) SIPEX

8 / 18 page

Rev. 8/21/01

SP2526 +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.

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