December 1998
1
MIC29311
MIC29311
Micrel
MIC29311
3A Fast-Response LDO Regulator for USB
Final Information
General Description
The MIC29311 is a 3A, fast response, low-dropout (LDO)
voltage regulator. Using Micrel's proprietary Super
eta
PNPTM 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 (300m
) 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.
Typical Application
ON/OFF
OVERCURRENT
3.3V USB Controller
V
BUS
D+
D
GND
V
BUS
D+
D
GND
MIC5207-3.3
LDO Regulator
IN
OUT
GND
33F
Ferrite
Bead
V
BUS
D+
D
GND
D+
D
V+
Bold lines indicate
0.1" wide, 1-oz. copper
high-current traces.
Downstream
USB
Port 1
4.75V min
500mA max.
33F
V
BUS
D+
D
GND
33F
0.01F
0.01F
0.01F
4.7
F
1.0
F
GND
33F
6.3Vac
3A
IN
OUT
GND
MIC29311-5.1
LDO Regulator
5.8V @ 3A
5.1V
FLAG
EN
10k
47F
10k
Downstream
USB
Port 2
4.75V min
500mA max.
Downstream
USB
Port 6
4.75V min
500mA max.
100mA
max.
AC
Line
Upstream
USB Port
Simple USB Stand-Alone 6-Port Self-Powered Hub
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
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
MIC29311
Micrel
MIC29311
2
December 1998
Ordering Information
Part Number
Voltage
Temperature Range
Package
MIC29311-5.1BT
5.1V
0
C to +125
C
TO-220-5
MIC29311-5.1BU
5.1V
0
C to +125
C
TO-263-5
Pin Description
Pin Number
Pin Name
Pin Function
1
EN
Enable (Input): Logic-level high enable/logic-level low shutdown control.
2
IN
Unregulated Input: +16V maximum supply.
3,
TAB
GND
Ground: Ground pin and
TAB
are internally connected.
4
OUT
Regulator Output
5
ERR
Error Flag (Output): Open-collector (active-low) output. Active low indicates
overcurrent or undervoltage output conditions.
Pin Configuration
TAB
5
ERR
4
OUT
3
GND
2
IN
1
EN
TO-220-5 (T)
TAB
5
ERR
4
OUT
3
GND
2
IN
1
EN
TO-263-5 (U)
December 1998
3
MIC29311
MIC29311
Micrel
Electrical Characteristics
T
A
= 25
C, bold values indicate 0
C
T
J
+125
C; unless noted.
Parameter
Condition
Min
Typ
Max
Units
Output Tolerange
10mA
I
OUT
< 3A, (V
OUT
+ 1V)
V
IN
8V
3
+3
%
Line Regulation
I
OUT
= 10mA, (V
OUT
+ 1V)
V
IN
8V
0.06
0.5
%
Load Regulation
V
IN
= V
OUT
+ 1V, 10mA
I
OUT
3A
0.2
1
%
Output Voltage Temperature
Note 5
20
100
ppm/
C
Coefficient
Dropout Voltage, Note 6
I
OUT
= 100mA
80
200
mV
I
OUT
= 750mA
220
mV
I
OUT
= 1.5A
330
mV
I
OUT
= 3A
600
1000
mV
Ground Current, Note 7
V
IN
= 6.1V, I
OUT
= 750mA
5
20
mA
V
IN
= 6.1V, I
OUT
= 1.5A
15
mA
V
IN
= 6.1V, I
OUT
= 3A
60
150
mA
Dropout Ground Current
V
IN
= 4.6V, I
OUT
= 10mA
2
3
mA
Current Limit
V
IN
= 3V, V
OUT
= 0V
3.0
3.8
A
Minimum Load Current
7
10
mA
Output Noise Voltage
C
LOAD
= 10
F
400
V(rms)
C
LOAD
= 33
F
260
V(rms)
Error Flag Output
Output Leakage Current
V
IN
= 6.1V, V
ERR
= 8V
0.1
1
A
2
A
Output Low Voltage
V
IN
= 4.1V, I
ERR
= 250
A
220
300
mV
400
mV
Absolute Maximum Ratings
(Note 1)
Input Voltage (V
IN
) ........................................ 20V to +12V
Enable Voltage (V
EN
) .................................... 20V to +12V
Error Output Voltage (V
ERR
) ............................. 0V to +12V
Lead Temperature (soldering, 5 sec.) ....................... 260
C
ESD Rating, Note 3
Operating Ratings
(Note 2)
Input Voltage (V
IN
) ........................................................ +8V
Maximum Power Dissipation (P
D(max)
) ..................... Note 4
Junction Temperature (T
J
) ........................... 0
C to +125
C
Package Thermal Resistance
TO-220-5
(
JA
) .................................................... 55
C/W
TO-220-5
(
JC
) ...................................................... 2
C/W
TO-263-5
(
JC
) ...................................................... 2
C/W
MIC29311
Micrel
MIC29311
4
December 1998
Parameter
Condition
Min
Typ
Max
Units
Enable Input
Logic Low Voltage
regulator shutdown
0.8
V
Logic High Voltage
regulator enabled
2.4
V
Enable Input Current
V
EN
= V
IN
15
30
A
75
A
V
EN
= 0.8V
2
A
4
A
Regulator Output Current
V
IN
=
8V, V
EN
0.8V (shutdown), V
OUT
= 0V, Note 8
10
20
A
Note 1.
Exceeding the absolute maximum rating may damage the device.
Note 2.
The device is not guaranteed to function outside its operating rating.
Note 3.
Devices are ESD sensitive. Handling precautions recommended.
Note 4.
P
D(max)
= (T
J(max)
T
A
)
JA
, where
JA
depends upon the printed curcuit board layout. See "Applications Information."
Note 5.
Output voltage temperature coefficient is defined as the
V
OUT(worst case)
(T
J(max)
T
J(min)
) where T
J(max)
is +125
C and T
J(min)
is 0
C.
Note 6.
V
DO
= V
IN
V
OUT
when V
OUT
decreases to 99% of its nominal output voltage with V
IN
= V
OUT
+ 1V.
Note 7.
I
GND
is the quiescent current. I
IN
= I
GND
+ I
OUT
.
Note 8.
V
EN
0.8V and V
IN
8V, V
OUT
= 0.
December 1998
5
MIC29311
MIC29311
Micrel
Typical Characteristics
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0
1
2
3
DROPOUT VOLTAGE (V)
OUTPUT CURRENT (A)
Dropout Voltage
vs. Output Current
0
0.2
0.4
0.6
0.8
1.0
0
30
60
90
120
150
DROPOUT VOLTAGE (mV)
TEMPERATURE (
C)
MIC2931x Dropout Voltage
vs. Temperature
I
LOAD
= 3A
0
1
2
3
4
5
6
7
0
2
4
6
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Dropout
Characteristics
I
LOAD
= 3A
I
LOAD
= 10mA
0.0
0.5
1.0
1.5
2.0
0
2
4
6
8
10
GROUND CURRENT (mA)
INPUT VOLTAGE (V)
Ground Current
vs. Input Voltage
I
OUT
= 10mA
0
50
100
150
200
0
2
4
6
8
10
GROUND CURRENT (mA)
INPUT VOLTAGE (V)
Ground Current
vs. Input Voltage
I
OUT
= 3A
-0.5
0.0
0.5
1.0
1.5
2.0
-20
-10
0
10
20
GROUND CURRENT (mA)
INPUT VOLTAGE (V)
Ground Current
vs. Input Voltage
R
LOAD
= 100
V
OUT
= 3.3V
0
1
2
3
4
5
6
0
30
60
90
120
150
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
OUT
= 750mA
0
5
10
15
20
0
30
60
90
120
150
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
OUT
= 1.5A
0
20
40
60
80
100
0
30
60
90
120
150
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
OUT
= 3A
0
10
20
30
40
50
60
0
1
2
3
GROUND CURRENT (mA)
OUTPUT CURRENT (A)
Ground Current
vs. Output Current
5.00
5.02
5.04
5.06
5.08
5.10
5.12
5.14
5.16
5.18
5.20
0
30
60
90
120
150
OUTPUT VOLTAGE (V)
TEMPERATURE (
C)
Output Voltage
vs. Temperature
0
1
2
3
4
5
6
0
30
60
90
120
150
CURRENT (A)
TEMPERATURE (
C)
Short Circuit
Current vs. Temperature
V
OUT
= 0V
Awaiting Further
Characterization
Data
Awaiting Further
Characterization
Data
MIC29311
Micrel
MIC29311
6
December 1998
0
5
10
15
20
25
30
35
40
0
30
60
90
120
150
ENABLE CURRENT (
A)
TEMPERATURE (
C)
Enable Current
vs. Temperaure
V
EN
= 5V
V
EN
= 2V
0.001
0.01
0.1
1
10
10x10
0
100x10
0
1x10
3
10x10
3
100x10
3
1x10
6
OUTPUT IMPEDANCE (
)
FREQUENCY (Hz)
Output Impedance
vs. Frequency
0mA
200mA
3A
5.1V
+20mV
20mV
LOAD CURRENT OUTPUT VOLTAGE
Load Transient Response
(See Test Circuit Schematic)
1ms/division
8.0V
6.0V
5.1V
+20mV
20mV
OUTPUT VOLTAGE INPUT VOLTAGE
Line Transient Response
with 3A Load, 10
F Output Capacitance
200
s/division
I
OUT
= 3A
C
OUT
=10
F
8.0V
6.0V
5.1V
+20mV
20mV
OUTPUT VOLTAGE INPUT VOLTAGE
Line Transient Response
with 3A Load, 100
F Output Capacitance
200
s/division
I
OUT
= 3A
C
OUT
= 100
F
V
IN
= V
OUT
+ 1V
MIC29311-5.1
EN
IN
OUT
ERR
GND
V
OUT
5.1V nominal
4 330F
AVX
TPSE337M006R0100
tantalum
I
OUT
switching between 200mA and 3A
1F
10k
Error
Output
Load Transcient Response Test Circuit
December 1998
7
MIC29311
MIC29311
Micrel
Functional Diagram
Reference
18V
O.V.
I
LIMIT
Thermal
Shut-
down
1.240V
1.180V
EN
IN
FLAG
GND
OUT
R1*
R2*
MIC29311
Micrel
MIC29311
8
December 1998
Applications Information
The MIC29311 is a high-performance low-dropout voltage
regulator suitable for all moderate to high-current voltage
regulator applications. The 600mV dropout voltage at full
load makes it especially valuable in battery-powered systems
and as high-efficiency noise filters in "post-regulator" applica-
tions. Its unique output voltage makes the MIC39311 ideal for
Universal Serical Bus (USB) power switching applications.
Unlike older NPN-pass transistor designs, where the mini-
mum dropout voltage is limited by the base-emitter voltage
drop and collector-emitter saturation voltage, dropout perfor-
mance of the PNP output of these devices is limited merely
by the low V
CE
saturation voltage.
A trade-off for the low dropout voltage is a varying base drive
requirement. But Micrel's Super
eta PNPTM process re-
duces this drive requirement to merely 1% to 5% of the load
current.
The MIC29311 regulator is fully protected from damage due
to fault conditions. Current limiting is provided. This limiting is
linear; output current under overload conditions is constant.
Thermal shutdown disables the device when the die tem-
perature exceeds the maximum safe operating temperature.
Transient protection allows device (and load) survival even
when the input voltage spikes above and below nominal. The
output structure of these regulators allows voltages in excess
of the desired output voltage to be applied without reverse
current flow. The MIC29311 version offers a logic level on-off
control: when disabled, the device draws nearly zero current.
MIC29311-5.1
IN
OUT
GND
V
IN
V
OUT
EN
FLG
Flag
Enable
Shutdown
Figure 1. Input and Output Capacitors
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires the following application-specific
parameters:
Maximum ambient temperature, T
A
Output Current, I
OUT
Output Voltage, V
OUT
Input Voltage, V
IN
First, calculate the power dissipation of the regulator from
these numbers and the device parameters from this datasheet.
P
I
1.02V
V
D
OUT
IN
OUT
=
-
(
)
Where the ground current is approximated by 2% of I
OUT
.
Then the heat sink thermal resistance is determined by:
SA
J(max)
A
D
JC
CS
T
T
P
=
-
-
+
Where T
J (max)
125
C and
CS
is between 0 and 2
C/W.
The heat sink may be significantly reduced in applications
where the minimum input voltage is known and is large
compared with the dropout voltage. Use a series input
resistor to drop excessive voltage and distribute the heat
between this resistor and the regulator. The low dropout
properties of Micrel Super eta PNP regulators allow very
significant reductions in regulator power dissipation and the
associated heat sink without compromising performance.
When this technique is employed, a capacitor of at least 1
F
is needed directly between the input and regulator ground.
Please refer to Application Note 9 for further details and
examples on thermal design and heat sink specification.
Capacitor Requirements
For stability and minimum output noise, a capacitor on the
regulator output is necessary. The value of this capacitor is
dependent upon the output current; lower currents allow
smaller capacitors. The MIC29311 regulator is stable with a
minimum capacitor value of 10
F at full load.
This capacitor need not be an expensive low ESR type:
aluminum electrolytics are adequate. In fact, extremely low
ESR capacitors may contribute to instability. Tantalum ca-
pacitors are recommended for systems where fast load
transient response is important.
Where the regulator is powered from a source with a high AC
impedance, a 0.1
F capacitor connected between Input and
GND is recommended. This capacitor should have good
characteristics to above 250kHz. When the regulator is
located more than 3 inches from the ac bulk supply capaci-
tors, a 1
F or greater input capacitor is recommended.
Minimum Load Current
The MIC29311 regulator is specified between finite loads. If
the output current is too small, leakage currents dominate
and the output voltage rises. A 10mA minimum load current
is necessary for proper regulation.
Enable Input
The MIC29311 version features an enable (EN) input that
allows on-off control of the device. Special design allows
"zero" current drain when the device is disabled--only micro-
amperes of leakage current flows. The EN input has TTL/
CMOS compatible thresholds for simple interfacing with
logic, or may be directly tied to V
IN
. Enabling the regulator
requires approximately 20
A of current into the EN pin.
Error Flag
The MIC29311 features an error flag which looks at the output
voltage and signals an error condition when this voltage
drops 5% below its expected value. The error flag is an open-
collector output that pulls low under fault conditions. It may
sink 10mA. Low output voltage signifies a number of possible
problems, including an overcurrent fault (the device is in
current limit) and low input voltage. The flag output is inopera-
tive during overtemperature shutdown conditions.
USB Applications
The main application of the MIC29311 is to control power
distribution in a self-powered Universal Serial Bus hub. For
self-powered hubs, the MIC29311 provides 5.1V
3% to
downstream ports from an unregulated supply voltage (see
December 1998
9
MIC29311
MIC29311
Micrel
"Typical Application"). USB requires that the downstream
voltage supplied to peripherals from a self-powered hub is
between 4.75V and 5.25V. The MIC29311 provides regula-
tion with this requirement. The enable pin input controls
ganged power for up to seven downstream ports, each
drawing up to 500mA. The device has an output current
limiting circuit that linearly decreases the output voltage as
the output current exceeds 3A. When the part is out of
regulation by 5%, the error flag goes low and signals a fault
condition to the microcontroller, allowing the system to be
disabled. This provides the overcurrent protection that is
required by USB.
In Figure 2, the MIC29311 provides power to the MIC2527
quad power switches. The MIC2527 provides power switch-
ing to four independently controlled downstream ports. Two
MIC2527s can be used to provide a 6-port, self-powered hub
in conjunction with the MIC29311. The 5.1V output of the
MIC29311 is optimized to ensure that under maximum load
condition, the output voltage of each channel of the MIC2527
remains above 4.75V. This is the minimum voltage require-
ment for self-powered USB hubs. The output voltage is a
function of the minimum output voltage of the power supply,
the PCB trace resistance and the on-resistance of the switch.
Table 1 shows the maximum allowable on-resistance for a
5.1V power supply in a self-powered hub, assuming 30mV of
voltage drop due to PCB trace resistance. The 5.1V of the
MIC29311 and the 300m
on-resistance of each MIC2527
switch provides an economical solution to power manage-
ment of self-powered hubs.
l
a
n
i
m
o
N
e
g
a
t
l
o
V
y
l
p
p
u
S
e
c
n
a
r
e
l
o
T
m
u
m
i
n
i
M
e
g
a
t
l
o
V
m
u
m
i
x
a
M
e
g
a
t
l
o
V
m
u
m
i
x
a
M
R
N
O
V
0
1
.
5
%
1
V
5
0
.
5
V
5
1
.
5
m
0
4
5
%
2
V
5
V
2
.
5
m
0
4
4
%
3
V
5
9
.
4
V
5
2
.
5
m
0
4
3
%
4
V
9
.
4
V
3
.
5
--
%
5
V
5
8
.
4
V
6
3
.
5
--
Table 1. Max. Allowable On-Resistance
For further information concerning USB power management,
refer to Application Note 17 and Application Hint 30.
MIC29311-5.1
LDO Regulator
IN
OUT
GND
ON/OFF
OVERCURRENT
MIC2527
3.3V USB Controller
V
BUS
D+
D
GND
V
BUS
D+
D
GND
47k
MIC5207-3.3
LDO Regulator
IN
OUT
GND
33F*
Ferrite
Bead
D+
D
V+
ENA
IN
FLGA
IN
ENB
OUTA
FLGB
OUTB
Bold lines indicate
0.1" wide, 1-oz. copper
high-current traces.
Downstream
USB
Port 1
500mA max.
Downstream
USB
Port 2
500mA max.
33F*
0.1
F
V
BUS
D+
D
GND
V
BUS
D+
D
GND
33F*
ENC
OUTD
FLGC
END
GND
FLGD
GND
Downstream
USB
Port 3
500mA max.
Downstream
USB
Port 4
500mA max.
33F*
0.01F
0.01F
0.01F
0.01F
4.7
F
1F
GND
5.7V
* 33F, 16V tantalum or 100F, 10V electrolytic per port
OUTC
10k
4.75V min.
at 500mA
EN
ERR
5.1V
3%
Figure 2. 4-Port Self-Powered Hub
MIC29311
Micrel
MIC29311
10
December 1998
Package Information
0.018
0.008
(0.46
0.20)
0.268 REF
(6.81 REF)
0.032
0.005
(0.81
0.13)
0.550
0.010
(13.97
0.25)
7
Typ.
SEATING
PLANE
0.578
0.018
(14.68
0.46)
0.108
0.005
(2.74
0.13)
0.050
0.005
(1.27
0.13)
0.150 D
0.005
(3.81 D
0.13)
0.400
0.015
(10.16
0.38)
0.177
0.008
(4.50
0.20)
0.103
0.013
(2.62
0.33)
0.241
0.017
(6.12
0.43)
0.067
0.005
(1.70
0.127)
inch
(mm)
Dimensions:
5-Lead TO-220 (T)
0.067
0.005
0.032
0.003
0.360
0.005
0.600
0.025
0.405
0.005
0.060
0.005
0.176
0.005
8
MAX
0.100
0.01
0.050
0.005
0.015
0.002
0.004+0.004
0.008
SEATING PLANE
0.065
0.010
20
2
DIM. = INCH
5-Lead TO-263 (U)
December 1998
11
MIC29311
MIC29311
Micrel
MIC29311
Micrel
MIC29311
12
December 1998
MICREL INC.
1849 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
1998 Micrel Incorporated
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