January 2005

1

MIC2044/2045

MIC2044/2045

Micrel

MIC2044/2045

Single Channel, High Current, Low Voltage,

Protected Power Distribution Switch

General Description

The MIC2044 and MIC2045 are high-side MOSFET switches

optimized for general purpose power distribution applications

that require circuit protection. These devices switch up to

5.5V and as low as 0.8V while offering both programmable

current limiting and thermal shutdown to protect the device

and the load. A fault status output is provided to indicate

overcurrent and thermal shutdown fault conditions. Both

devices employ soft-start circuitry to minimize the inrush

current in applications that employ highly capacitive loads.

Additionally, for tighter control over inrush current during start

up, the output slew-rate may be adjusted by an external

capacitor.

The MIC2045 features a auto-reset circuit breaker that latches

the output OFF upon detecting an overcurrent condition

lasting more than 32ms. The output is reset by removing or

reducing the load.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Typical Application

7, 11,

13, 16

8

2

3

6

4

15

9,12,14

1

5

100W

Note:

Output Power-Good = 3.0V.

*C4 is optional. See "Applications Information."

C4*

0.022mF

C1

0.1mF

Logic

Controller

ON/OFF

OVERCURRENT

IN

10

MIC2044-1BTS

MIC39100-2.5BS

VBIAS

VIN

EN

/FAULT

ILIM

SLEW

2.5V

VOUT

PGREF

PWRGD

UVLOIN

GND

R1

20kW

R2

1%

R3

1%

EN

IN

GND

OUT

3.3V@ 3.5A

R4

20kW

(OPEN)

+3.3V

Power

Supply

OUT1

OUT2

C3

4.7mF

C2

0.1mF

Features

• 30mΩ maximum on-resistance

• 0.8V to 5.5V operating range

• Adjustable current limit

• Up to 6A continuous output current

• Short circuit protection

• Very fast reaction to short circuits

• Thermal shutdown

• Adjustable slew-rate control

• Circuit breaker mode (MIC2045)

• Fault status flag

• Power-Good detection

• Undervoltage lockout

• No reverse current flow through the switching MOSFET

when OFF or disabled

• Low quiescent current

Applications

• Docking stations

• LAN servers

• WAN switches

• Hot swap board insertions

• Notebook PCs

• PDAs

• Base stations

• RAID controllers

• USB hosts

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