FEATURES

• Compatible with USB1.1 and USB 2.0

• 90mΩ (typ.) High-Side MOSFET Switch

• 500mA Continuous Current per Port

• 7 ms Fault Flag Delay Filters Hot-Plug Events

• Industry Standard Pin Order

• Short Circuit Protection with Power-Saving

Current Foldback

• Thermal Shutdown Protection

• Undervoltage Lockout

• Recognized by UL and Nemko CB

• Input Voltage Range: 2.7V to 5.5V

• 5μA Maximum Standby Supply Current

• 16-Pin SOIC Package

• Ambient Temperature Range: −40°C to 85°C

APPLICATIONS

• USB Root, Self-Powered, and Bus-Powered

Hubs fold•

USB Devices such as Monitors and Printers

• General Purpose High Side Switch

Applications

DESCRIPTION

The LM3544 is a quad high-side power switch that is

an excellent choice for use in Root, Self-Powered and

Bus- Powered USB (Universal Serial Bus) Hubs.

Independent port enables, flag signals to alert USB

controllers of error conditions, controlled start-up in

hot-plug events, and short circuit protection all satisfy USB requirements.

The LM3544 accepts input voltages between 2.7V

and 5.5V. The Enable logic inputs, available in active-

high and active-low versions, can be powered off any

voltage in the 2.7V to 5.5V range. The LM3544 limits

the continuous current through a single port to 1.25A

(max.) when it is shorted to ground.

The low on-state resistance of the LM3544 switches

ensures the LM3544 will satisfy USB voltage drop

requirements, even when current through a switch

reaches 500 mA. Thus, High-Powered USB

Functions, Low-Powered USB functions, and Bus-

Powered USB Hubs can all be powered off a Root or

Self-Powered USB Hub containing the LM3544.

Added features of the LM3544 include current fold•

back to reduce power consumption in current overload conditions, thermal shutdown to prevent

device failure caused by high current overheating,

and undervoltage lockout to keep switches from

operating if the input voltage is below acceptable

levels.