MIC2537 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – Quad Power Distribution Switch Preliminary Information

MIC2537
Micrel
MIC2537
Quad Power Distribution Switch
Preliminary Information
General Description
The MIC2537 is a cost-effective high-side power switch with
four independently controlled channels, optimized for bus-
powered Universal Serial Bus (USB) applications. Few exter-
nal components are necessary to satisfy USB requirements.
The MIC2537 satisfies the following USB requirements: each
switch channel supplies up to 100mA as required by USB
bus-powered downstream devices; fault current is limited to
typically 250mA, well below the UL 25VA safety require-
ments; and a flag output is available to indicate fault condi-
tions to the local USB controller. Soft start eliminates the
momentary voltage drop on the upstream port 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 MIC2537 is available in active-high and active-low ver-
sions in a 16-lead SOP package.
Features
• Compliant to USB specifications
• 3V to 5.5V input
• 100mA minimum continuous load current per port
• 425mΩ typical on-resistance
• < 400mA current limit
• Individual open-drain fault flag leads
• 3V/5V-compatible enable inputs
• Active-high (-1) and active-low (-2) versions
• 100µA max. on-state supply current
• <1µA typical off-state supply current
• 16-lead SOP package
• –40°C to 85°C operation
Applications
• USB keyboards
• USB bus-powered docking stations
• Notebook docking stations
• Notebook PCs
• PDA
• General power distribution
Typical Application
Upstream V_BUS
4.75V to 5.25V
500mA max.
MIC5207-3.3
LDO Regulator
10k
3.3V USB Controller
IN
OUT
V+
4.7
1µF
µF
GND
D+
D–
Bold lines indicate
0.1" wide, 1-oz. copper
high-current traces.
EN
OC
EN
OC
EN
OC
EN
GND ^OC
10k 10k 10k
* 33µF, 16V tantalum or 100µF, 10V electrolytic per port
MIC2537
ENA
IN
FLGA
NC
ENB OUTA
FLGB OUTB
ENC OUTC
FLGC OUTD
END
NC
FLGD GND
33µF*
0.1
µF
33µF*
33µF*
33µF*
Ferrite
Bead
0.01µF
V_BUS
D+
D–
GND
0.01µF
V_BUS
D+
D–
GND
0.01µF
V_BUS
D+
D–
GND
0.01µF
V_BUS
D+
D–
GND
Downstream
USB
Port 1
100mA max.
Downstream
USB
Port 2
100mA max.
Downstream
USB
Port 3
100mA max.
Downstream
USB
Port 4
100mA max.
Typical Bus-Powered Hub
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
December 1999
1
MIC2537