March 2000

1

MIC2536

MIC2536

Micrel

MIC2536

Dual USB Power Distribution Switch

Preliminary Information

General Description

The MIC2536 is a cost-effective high-side power switch, with

two independently controlled channels, optimized for bus-

powered Universal Serial Bus (USB) applications. Few exter-

nal components are necessary to satisfy USB requirements.

Each switch channel of the MIC2536 will supply up to 100mA

as required for USB bus-powered downstream devices. Fault

current is limited to typically 275mA by fast-acting current-

limit circuitry which minimizes voltage droop on the upstream

port during fault conditions. A flag output with transient filter

indicates fault conditions to the local USB controller but will

ignore short flag signals resulting from inrush current during

hot plug-in events.

Soft start eliminates the momentary voltage droop on other

ports that may occur when the switch is enabled in bus-

powered applications. Additional features include thermal

shutdown to prevent catastrophic switch failure from high-

current loads and 3.3V and 5V logic compatible enable

inputs.

The MIC2536 is available in active-high and active-low ver-

sions in 8-lead SOP and MSOP.

Typical Application

ENA

OUTA

FLGA

IN

FLGB

GND

ENB

OUTB

MIC2536-2

3.3V USB Controller

0.1µF

D+

D–

GND

Data

(Two Pair)

D+

D–

GND

USB

Port 2

USB

Port 1

MIC5207-3.3

63µF

63µF

Ferrite

Beads

4.50V to 5.25V

100mA max.

D+

D–

GND

Data

4.7µF

1µF

to USB

Controller

1.5k

ON/OFF

OVERCURRENT

OVERCURRENT

ON/OFF

VIN

10k

IN

OUT

GND

.01µF

.01µF

10k

Typical Two-Port Bus-Powered Hub

Features

• Compliant to USB specifications

• 2.7V to 5.5V operating range

• 150mA minimum continuous load current per channel

• 400m

Ω typical on-resistance

• Fast-acting short circuit protection with

thermal shutdown

• Integrated filter eliminates

false overcurrent flag assertions

• Individual open-drain fault flag pins with transient filter

• 3V/5V-compatible enable inputs

• Active-high (-1) and active-low (-2) versions

• Reverse-current blocking in off mode (no “body diode”)

• Soft-start circuit

• 100

µA maximum on-state supply current

• <1

µA typical off-state supply current

•–40

°C to 85°C operation

Applications

• USB keyboard bus-powered hubs

• USB bus-powered docking stations

• Note Book PCs

• PDAs

• General purpose power distribution applications

• PC board hot swap

• Inrush current-limiting

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com