MIC29311 Datasheet, PDF (1/12 Pages) Micrel Semiconductor – 3A Fast-Response LDO Regulator for USB Preliminary Information

MIC29311
Micrel
MIC29311
3A Fast-Response LDO Regulator for USB
Preliminary Information
General Description
The MIC29311 is a 3A, fast response, low-dropout (LDO)
voltage regulator. Using Micrel’s proprietary Super βeta
PNP™ process, the MIC29311 offers exceptional dropout
(600mV at 3A) and low ground current (60mA at 3A). Fast
transient response allows it to recover quickly from large load
changes while maintaining a steady output. The device can
be sent into a “zero-current” off mode when the TTL compat-
ible enable is brought low.
Designed specifically for Universal Serial Bus (USB) applica-
tions, the MIC29311 works with USB power switches to
provide an economical solution for self-powered hubs. The
5.1V output voltage is optimized to work with lower-cost high
on-resistance USB power switches (300mΩ) to provide a
minimum of 4.75V at 500mA to downstream ports. Used with
MIC2527 quad USB power switches, the MIC29311 can
power up to 6 downstream ports.
Features of the MIC29311 include thermal shutdown, current
limit, reversed-battery and reversed-lead insertion protec-
tion. An overvoltage clamp is available to maintain a safe
output when the input voltage exceeds 8V. An error flag is
also available to indicate of the output falls out of regulation,
or when an overcurrent condition occurs.
The MIC29311 is available in a 5-pin TO-220 or TO-263
package with a fixed 5.1V output voltage.
For other high current, low-dropout voltage regulators, please
see the MIC29150/300/500/750 and the MIC29310,
MIC29510, MIC29710.
Features
• Fast transient response
• 3A output current over full temperature range
• 600mV dropout voltage at full load
• Low ground current
• 3% total accuracy
• “Zero” off-mode current
• Thermal Shutdown
• Current Limiting
• Reversed battery protection
• Fixed 5.1V Output
Applications
• Self-powered USB hubs
• USB power switching
• High-efficiency linear power supplies
• High-efficiency switching supply post-regulator
Typical Application
AC
6.3Vac
Line
3A
V_BUS
100mA
max.
MIC5207-3.3
LDO Regulator
IN
OUT
D+
D–
GND
GND
4.7
µF
Upstream
USB Port
47µF
MIC29311-5.1
LDO Regulator
5.8V @ 3A
IN
5.1V
OUT
EN FLAG
10k
GND
3.3V USB Controller
33µF
V+
ON/OFF
1.0 _OVERCURRENT
µF
D+
D– _GND
Bold lines indicate
10k
0.1" wide, 1-oz. copper
high-current traces.
33µF
33µF
Ferrite
Bead
0.01µF
V_BUS
D+
D–
GND
Downstream
USB
Port 1
4.75V min
500mA max.
0.01µF
V_BUS
D+
D–
GND
Downstream
USB
Port 2
4.75V min
500mA max.
33µF
0.01µF
V_BUS
D+
D–
GND
Downstream
USB
Port 6
4.75V min
500mA max.
Simple USB Stand-Alone 6-Port Self-Powered Hub
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
December 1998
1
MIC29311