4

Rev. 8/21/01

SP2525 +3.0 to +5.5 Power Control Switch

© Copyright 2001 Sipex Corporation

FEATURES

The SP2525 device is a single +3.0V to +5.5V

USB Supervisory Power Control Switch ideal

for self-powered and bus-powered Universal

Serial Bus (USB) applications. USB provides

a +5.0V bus and ground return line in addition

to a twisted pair line for data.

Features of the SP2525 device include current

limiting, a +2.7V undervoltage lockout, over-

temperature shutdown, error flag output, soft

start power up, a switch-on resistance of 140m

Ω

over the entire supply range, and a supply

current of 80

µA. The SP2525-1 device has

active-high inputs. The SP2525-2 device has

active-low inputs.

THEORY OF OPERATION

There are operational conditions that will en-

able or disable one or more of the output

transistors, depending on the type of hazard.

Certain conditions will activate the open-drain

error flag transistors forcing the flag output to

ground. The SP2525 device is a single inte-

grated high-side power switch optimized for

self-powered and bus-powered Universal Se-

rial Bus (USB) applications. The SP2525 de-

vice provides the following functions:

1) Solid State Switch : MOSFET M1 connects

the IN pin to the OUT pins when enabled by a

logic signal at the EN pin.

2) Fault Flag Conditions : The FLG pin is an

N-channel, open-drain MOSFET output ca-

pable of sinking a 10mA load to typically

100mV above ground.

3) Undervoltage Lockout : The lockout mecha-

nism monitors the input voltage and will enable

the MOSFET switch only when the input sig-

nal is >2.7V.

4) Current Limiting Threshold : A current

limiting threshold is set internally to prevent

any damage to the device and external load.

5) Thermal Shutdown : This mechanism pro-

tects the device switch and signals a fault condi-

MOSFET switches from turning on until the die

Input and Output

The independent solid state switch connects the

IN pin to the OUT pin when enabled by a logic

signal at EN. The IN pin is the power supply

connection to the internal circuitry and the drain

of the output MOSFET. The OUT pin is the

source of the MOSFET.

Typically, the current in USB application will

flow through the switch from IN to OUT towards

the load. If V

is enabled, the current will flow from OUT to the

IN pin because the MOSFET channels are bidi-

rectional when switched on.

Under normal operating conditions, the MOSFET

switch will present 140m

Ω maximum resistance

when closed. The device is designed to allow

out pin to be externally forced to a higher voltage

than the IN pin when the switch is off.

Fault Flag Conditions

The fault flag is an N-channel, open drain

MOSFET output. The active low fault flag is

asserted when one of the following conditions

exist:

1. Undervoltage

2. Soft Start

3. Overcurrent

4. Overtemperature

Undervoltage Lockout

This voltage lockout mechanism prevents the

output MOSFET switches from turning on until

V

After the switch turns on, if the voltage at V

IN

drops below +2.5V, the lockout circuitry shuts

off the output MOSFET switch and signals the

FLG fault flag. In the undervoltage lockout

state, the FLG pin will be at a logic low. This

detection functions only when the MOSFET

switch is enabled.