MIC49300
3A Low Voltage LDO Regulator with Dual
Input Voltages
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 22, 2014
Revision 3.0
General Description
The MIC49300 is a high-bandwidth, low-dropout, 3.0A
voltage regulator ideal for powering core voltages of low-
power microprocessors. The MIC49300 implements a dual
supply configuration allowing for very low output
impedance and very fast transient response.
The MIC49300 requires a bias input supply and a main
input supply, allowing for ultra-low input voltages on the
main supply rail. The input supply operates from 1.4V to
6.5V and the bias supply requires between 3V and 6.5V
for proper operation. The MIC49300 offers fixed output
voltages from 0.9V to 1.8V and adjustable output voltages
down to 0.9V.
The MIC49300 requires a minimum of output capacitance
for stability, working optimally with small ceramic
capacitors.
The MIC49300 is available in a 5-pin S-Pak. It operates
over a junction temperature range of –40°C to +125°C.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
Input voltage range:
VIN: 1.4V to 6.5V
VBIAS: 3.0V to 6.5V
Stable with 1µF ceramic capacitor
±1% initial tolerance
Maximum dropout voltage (VIN–VOUT) of 500mV over
temperature
Adjustable output voltage down to 0.9V
Ultra-fast transient response (up to 10MHz bandwidth)
Excellent line and load regulation specifications
Logic controlled shutdown option
Thermal shutdown and current limit protection
Power S-Pak package
Junction temperature range of –40°C to +125°C
Applications
Graphics processors
PC add-in cards
Microprocessor core voltage supply
Low voltage digital ICs
High efficiency linear power supplies
SMPS post regulators
Typical Application
Micrel, Inc.
MIC49300
January 22, 2014
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Revision 3.0
Ordering Information
Part Number(1, 2)
Output Current
Voltage
Temperature Range
Package
MIC49300-0.9WR
3A
0.9V
–40° to +125°C
S-PAK-5
MIC49300-1.2WR
3A
1.2V
–40° to +125°C
S-PAK-5
MIC49300-1.5WR
3A
1.5V
–40° to +125°C
S-PAK-5
MIC49300-1.8WR
3A
1.8V
–40° to +125°C
S-PAK-5
MIC49300WR
3A
Adj.
–40° to +125°C
S-PAK-5
Note:
1. Other voltages are available. Contact Micrel for details.
2. RoHS-compliant with ‘high-melting solder’ exemption.
Pin Configuration
5-Pin S-Pak (R)
Pin Description
Pin Number
Pin Name
Pin Function
1
EN
Enable (input): CMOS-compatible input. Logic high = enable, logic low = shutdown.
ADJ
Adjustable regulator feedback input. Connect to resistor voltage divider.
2
VBIAS
Input bias voltage for powering all circuitry on the regulator with the exception of the output power
device.
3
GND
Ground (TAB is connected to ground on S-Pak).
4
VIN
Input voltage that supplies current to the output power device.
5
VOUT
Regulator output.
Micrel, Inc.
MIC49300
January 22, 2014
3
Revision 3.0
Absolute Maximum Ratings(3)
Supply Voltage (VIN) ....................................................... +8V
Bias Supply Voltage (VBIAS) ............................................ +8V
Enable Input Voltage (VEN) ............................................. +8V
Power Dissipation ..................................... Internally Limited
ESD Rating(5) .................................................................. 2kV
Operating Ratings(4)
Supply Voltage (VIN) ..................................... +1.4V to +6.5V
Bias Supply Voltage (VBIAS) ............................. +3V to +6.5V
Enable Input Voltage (VEN) .................................. 0V to VBIAS
Junction Temperature Range ............. –40°C ≤ TJ ≤ +125°C
Package Thermal Resistance
S-PAK (JC) .......................................................... 2°C/W
Electrical Characteristics(6)
TA = 25°C with VBIAS = VOUT + 2.1V; VIN = VOUT + 1V; bold values indicate –40°C≤ TJ ≤ +125°C, unless noted.
Parameter
Condition
Min.
Typ.
Max.
Units
Output Voltage Accuracy
At 25°C, fixed voltage options
Over temperature range
-1
1
%
-2
2
%
Line Regulation
VIN = 2.0V to 6.5V
-0.1
0.01
0.1
%/V
Load Regulation
IL = 0mA to 3A
0.2
0.5
%
Dropout Voltage (VIN – VOUT)
IL = 1.5A
125
200
mV
IL = 3A
280
400
mV
Dropout Voltage (VBIAS – VOUT), Note 7
IL = 3A
1.5
2.1
V
Ground Pin Current, Note 8
IL = 0mA
25
mA
IL = 3A
25
50
mA
Ground Pin Current in Shutdown
VEN ≤ 0.6V, (IBIAS + ICC), Note 8
0.07
5
µA
Current through VBIAS
IL = 0mA
20
35
mA
IL = 3A
50
150
mA
Current Limit
VOUT = 0V
6.5
9
A
Enable Input, Note 9
Enable Input Threshold (fixed voltage only)
Regulator enable
1.6
V
Regulator shutdown
0.6
V
Enable Pin Input Current
0.1
1.0
µA
Reference
Reference Voltage
Adjustable option only
0.891
0.9
0.909
V
0.882
0.918
V
Notes:
3. Exceeding the absolute maximum ratings may damage the device.
4. The device is not guaranteed to function outside its operating ratings.
5. Devices are ESD sensitive. Handling precautions are recommended. Human body model, 1.5kΩ in series with 100pF.
6. Specification for packaged product only.
7. For VOUT ≤1V, VBIAS dropout specification does not apply due to a minimum 3V VBIAS input.
8. IGND = IBIAS + (IIN – IOUT). At high loads, input current on VIN will be less than the output current, due to drive current being supplied by VBIAS.
9. Fixed output voltage versions only.
Micrel, Inc.
MIC49300
January 22, 2014
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Functional Diagram
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MIC49300
January 22, 2014
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Typical Characteristics
Micrel, Inc.
MIC49300
January 22, 2014
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Typical Characteristics (Continued)
Micrel, Inc.
MIC49300
January 22, 2014
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Applications Information
The MIC49300 is an ultra-high performance, low dropout
linear regulator designed for high current applications
requiring fast transient response. The MIC49300 utilizes
two input supplies, significantly reducing dropout voltage,
perfect for low-voltage, DC-to-DC conversion. The
MIC49300 requires a minimum of external components
and obtains a bandwidth of up to 10MHz. As a µCap
regulator, the output is tolerant of virtually any type of
capacitor including ceramic and tantalum.
The MIC49300 regulator is fully protected from damage
due to fault conditions, offering linear current limiting and
thermal shutdown.
Bias Supply Voltage
VBIAS, requiring relatively light current, provides power to
the control portion of the MIC49300. VBIAS requires
approximately 33mA for a 1.5A load current. Dropout
conditions require higher currents. Most of the biasing
current is used to supply the base current to the pass
transistor. This allows the pass element to be driven into
saturation, reducing the dropout to 300mV at a 1.5A load
current. Bypassing on the bias pin is recommended to
improve performance of the regulator during line and load
transients. Small ceramic capacitors from VBIAS to
ground help reduce high frequency noise from being
injected into the control circuitry from the bias rail and are
good design practice. Good bypass techniques typically
include one larger capacitor such as a 1µF ceramic and
smaller valued capacitors such as 0.01µF or 0.001µF in
parallel with that larger capacitor to decouple the bias
supply. The VBIAS input voltage must be 1.6V above the
output voltage with a minimum VBIAS input voltage of 3V.
Input Supply Voltage
VIN provides the high current to the collector of the pass
transistor. The minimum input voltage is 1.4V, allowing
conversion from low voltage supplies.
Output Capacitor
The MIC49300 requires a minimum of output capacitance
to maintain stability. However, proper capacitor selection
is important to ensure desired transient response. The
MIC49300 is specifically designed to be stable with
virtually any capacitance value and ESR. A 1µF ceramic
chip capacitor should satisfy most applications. Output
capacitance can be increased without bound. See Typical
Characteristics for examples of load transient response.
X7R dielectric ceramic capacitors are recommended
because of their temperature performance. X7R-type
capacitors change capacitance by 15% over their
operating temperature range and are the most stable
type of ceramic capacitors. Z5U and Y5V dielectric
capacitors change value by as much as 50% and 60%,
respectively, over their operating temperature ranges. To
use a ceramic chip capacitor with Y5V dielectric, the
value must be much higher than an X7R ceramic or a
tantalum capacitor to ensure the same capacitance value
over the operating temperature range. Tantalum
capacitors have a very stable dielectric (10% over their
operating temperature range) and can also be used with
this device.
Input Capacitor
An input capacitor of 1µF or greater is recommended
when the device is more than 4 inches away from the
bulk supply capacitance, or when the supply is a battery.
Small, surface-mount, ceramic chip capacitors can be
used for the bypassing. The capacitor should be placed
within 1" of the device for optimal performance. Larger
values will help to improve ripple rejection by bypassing
the input to the regulator, further improving the integrity of
the output voltage.
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 (TA)
Output Current (IOUT)
Output Voltage (VOUT)
Input Voltage (VIN)
Ground Current (IGND)
First, calculate the power dissipation of the regulator from
these numbers and the device parameters from this
datasheet.
PD = VIN × IIN + VBIAS × IBIAS – VOUT × IOUT
The input current will be less than the output current at
high output currents as the load increases. The bias
current is a sum of base drive and ground current.
Ground current is constant over load current. Then the
heat sink thermal resistance is determined with this
formula:
)(
)(
CSJCD
AMAXJ
SA PTT
Equation 1
The heat sink may be significantly reduced in application
where the maximum input voltage is known and 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
Micrel, Inc.
MIC49300
January 22, 2014
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Revision 3.0
properties of the MIC49300 allow significant reductions in
regulator power dissipation and the associated heat sink
without compromising performance. When this technique
is employed, a capacitor of at least 1µF is needed directly
between the input and regulator ground. Refer to
Application Note 9 for further details and examples on
thermal design and heat sink specification.
Minimum Load Current
The MIC49300, unlike most other high current regulators,
does not require a minimum load to maintain output
voltage regulation.
Power Sequencing
There is no power sequencing requirement for VIN and
VBIAS giving more flexibility to the user.
Adjustable Regulator Design
The MIC49300 adjustable version allows programming
the output voltage anywhere between 0.9Vand 5V. Two
resistors are used. The resistor value between VOUT and
the adjust pin should not exceed 1kΩ. Larger values can
cause instability. The resistor values are calculated by:
1
9.0
21 OUTV
RR
Equation 2
Where VOUT is the desired output voltage.
Enable
The fixed output voltage versions of the MIC49300
feature an active high enable input (EN) that allows on-off
control of the regulator. Current drain reduces to “zero”
when the device is shut down, with only microamperes of
leakage current. The EN input has TTL/CMOS
compatible thresholds for simple logic interfacing. EN
may be directly tied to VIN and pulled up to the maximum
supply voltage.
Micrel, Inc.
MIC49300
January 22, 2014
10
Revision 3.0
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
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information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
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