June 2000

1

MIC2544/2548

MIC2544/2548

Micrel

MIC2544/2548

Programmable Current Limit High-Side Switch

Preliminary Information

General Description

The MIC2544 and MIC2548 are integrated high-side power

switches optimized for low loss dc power switching and other

power management applications, including Advanced Con-

figuration and Power Interface (ACPI). The MIC2544/48 is a

cost-effective, highly integrated solution that requires few

external components to satisfy USB and ACPI requirements.

Load current management features include a precision resis-

tor-programmable output current-limit and a soft-start circuit

which minimizes inrush current when the switch is enabled.

Thermal shutdown, along with current-limit, protects the

switch and the attached device.

The MIC2544/48’s open-drain flag output is used to indicate

current-limiting or thermal shutdown to a local controller. The

MIC2548 has an additional internal latch which turns the

output off upon thermal shutdown providing robust fault

control. The enable signal is compatible with both 3V and 5V

logic, and is also used as the thermal shutdown latch reset for

the MIC2548.

The MIC2544 and MIC2548 are available in active-high and

active-low enable versions in the 8-pin SOP (small-outline

package) and 8-pin MSOP (micro-small-outline package).

Typical Application

EN

FLG

GND

ILIM

OUT

IN

OUT

NC

MIC2544-xBM

On/Off

Peripheral

0.1µF

+5V

33µF

SOP pinout shown

Typical Advanced Configuration and Power Interface (ACPI) Application

Features

• 2.7V to 5.5V input

• Adjustable current-limit up to 1.5A

• Reverse current flow blocking (no “body diode”)

• 75

µA typical on-state supply current

• 1

µA typical off-state supply current

• 120m

Ω maximum on-resistance

• Open-drain fault flag

• Thermal shutdown

• Thermal shutdown output latch (MIC2548)

• 2ms (slow) turn-on and fast turnoff

• Available with active-high or active-low enable

Applications

• USB power distribution

• PCI Bus Power Switching

• Notebook PC

• ACPI power distribution

• PC card hot swap applications

• 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