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
R
SET
100W
Note:
All V
IN
pins (7, 11, 13, 16) must be externally tied together.
All V
OUT
pins (9, 12, 14) must be externally tied together.
I
LIMIT
= 4A.
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
294k
W
1%
R3
24.3k
W
1%
EN
IN
GND
OUT
C
LOAD
33m
F
V
OUT
3.3V@ 3.5A
R4
20kW
(OPEN)
+3.3V
Power
Supply
OUT1
OUT2
C3
4.7mF
C2
0.1mF
Features
• 30m
Ω
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
