MIC49500
5A Dual Supply, Low Voltage,
High Bandwidth LDO
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2007 M9999-071307
General Description
The MIC49500 is an ultra-high-bandwidth, low-
dropout, 5.0A voltage regulator ideal for powering
core voltages of low-voltage microprocessors. The
MIC49500 implements a dual supply configuration
allowing for very low output impedance and very fast
transient response.
The MIC49500 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 6V and the bias supply requires between
3V and 6V for proper operation. The MIC49500 can
regulate to an output voltage as low as 0.7V, making it
an ideal product for low-voltage to low-voltage
conversion.
The MIC49500 requires a minimum of output
capacitance for stability, working optimally with any
type of capacitor, including small ceramic capacitors.
Available in fixed output voltages from 0.9V to 1.8V
and adjustable output voltages down to 0.7V, the
MIC49500 comes in both 7-pin S-Pak and TO-263
packages. The MIC49500 is rated to the full operating
temperature range of –40°C to 125°C junction
temperature.
Features
• Input voltage range:
– V
IN
: 1.4V to 6V
– V
BIAS
: 3.0V to 6V
• Stable with 10µF ceramic output capacitor
• +
1.0% initial output tolerance
• Maximum dropout (V
IN
– V
OUT
) is 500mV over
temperature
• Adjustable output voltage down to 0.7V
• Ultra Fast Transient Response (Up to 10MHz
bandwidth)
• Excellent line and load regulation specifications
• Logic controlled shutdown option
• Thermal shutdown and current limit protection
• Thin 7-pin S-Pak package
• TO-263 7-pin package
• –40°C to +125°C operating junction temperature
range
Applications
• ASIC Core Voltage Regulator
• PLD/FPGA Core Power Supply
• Linear Point-of-Load Conversion
• High Speed Post-Regulator
Typical Application
IN
BIAS
OUT
ADJ
GND
MIC49500WR V
OUT
= 1.0V
C
OUT
= 10µF
Ceramic
V
BIAS
= 3.1V
V
IN
= 2.0V
C
BIAS
= 1µF
Ceramic
C
IN
= 1µF
Ceramic
R1
R2
EN
ONOFF
Low Voltage,
Fast Transient Response Regulator
Load Transient
Output Voltage
(50mV/div)
Output Current
(2A/div)
Time (10µs/div)
5A
0A
V
OUT
= 1.8V
V
IN
= 2.8V
C
OUT
= C
BIAS
= 10µF
V
BIAS
= 3.9V
Micrel, Inc. MIC49500
July 2007 2 M9999-071307
Block Diagram
EN Enable Bandgap
Ilimit
VBIAS
VIN
SNS / ADJ
VOUT
GND
ADJ
FIX (SNS)
ADJ
FIX
Micrel, Inc. MIC49500
July 2007 3 M9999-071307
Ordering Information
Part Number* Voltage Junction Temperature Ran ge Package Lead Finish*
MIC49500-0.9WR 0.9V –40°C to +125°C S-Pak-7 RoHS Compliant
MIC49500-1.2WR 1.2V –40°C to +125°C S-Pak-7 RoHS Compliant
MIC49500WR ADJ –40°C to +125°C S-Pak-7 RoHS Compliant
MIC49500-0.9WU 0.9V –40°C to +125°C TO-263 RoHS Compliant
MIC49500-1.2WU 1.2V –40°C to +125°C TO-263 RoHS Compliant
MIC49500WU ADJ –40°C to +125°C TO-263 RoHS Compliant
Other Voltage available. Contact Micrel for details.
* RoHS compliant with ‘high-melting solder’ exemption.
Pin Configur ation
7 VSNS/ADJ
6NC
5 VOUT
4 GND
3 VIN
2 VBIAS
1EN
MIC49500WU (TO263-7)MIC49500WR (S-Pak-7)
7 VSNS/ADJ
6NC
5 VOUT
4 GND
3 VIN
2 VBIAS
1EN
Pin Description
Pin Number
S-Pak-7 Pin Name
(Fixed) Pin Name
(Adj) Pin Function
1 EN EN
Enable: TTL/CMOS compatible input. Logic high = enable,
logic low or open = shutdown.
2 VBIAS VBIAS
Bias Supply: Bias supply input for powering all internal circuitry of
the device, except the main current path.
3 VIN VIN
Input Voltage: Main Power Input Supply. Supplies main current
to output device.
4 GND GND Ground (TAB is connected to Ground).
5 VOUT VOUT Output Voltage: Regulator Output.
6 NC No Connect
7 VSNS -
Remote Voltage Sense: Connect direct the load to improve
regulation. Connect direct to pin 5 if not used.
7 - ADJ
Adjust Input. Connect external resistor divider to program output
voltage.
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Absolute Maximum Ratings(1)
Supply Voltage (V
IN
) ............................................. 6.5V
Bias Supply Voltage (V
BIAS
) .................................. 6.5V
Enable Input Voltage (V
EN
)................................... 6.5V
Power Dissipation............................. Internally Limited
Junction Temperature .................-40°C ≤ T
J
≤ +125°C
Storage Temperature (TS) ........... -65°C ≤ TJ ≤ 150°C
Lead Temperature (soldering, 5 sec.)................260°C
ESD Rating
(3)
.........................................................3kV
Operating Ratings(2)
Supply voltage (V
IN
).......................................1.4V to 6V
Bias Supply Voltage (V
BIAS
)..............................3V to 6V
Enable Input Voltage (V
EN
)........................... 0V to V
BIAS
Junction Temperature Range........-40°C ≤ T
J
≤ +125°C
Package Thermal Resistance
S-Pak (θ
JC
) ................................................. 2°C/W
TO-263 (θ
JC
) ............................................... 2°C/W
Electrical Characteristics(4)
V
IN
= V
OUT
+ 1.0V; V
BIAS
= V
OUT
+ 2.1V; C
OUT
= 10µF; I
OUT
= 10mA; T
J
= 25°C,
bold
values indicate –40°C to +125°C,
unless noted.
Parameter Conditions Min Typ Max Units
Output Voltage Accuracy At 25°C, fixed voltage options
Over temperature range
–1
–2
+1
+2
%
%
Output Voltage Line
Regulation
V
IN
= V
OUT
+ 1V to 6V -0.1 +0.1
%/V
Output Voltage Load
Regulation
I
L
= 10mA to 5A 0.2 1.0 %
V
IN
– V
O
; Dropout Voltage I
L
= 2.5A
I
L
= 5.0A
145
290
300
500 mV
mV
V
BIAS
– V
O
; Dropout Voltage I
L
= 2.5A
I
L
= 5.0A
1.5
1.7
2.0
2.1 V
V
Ground Pin Current V
OUT
= 1.2V; I
L
= 0mA
V
OUT
= 1.2V; I
L
= 5.0A
0.7V ≤ V
OUT
≤ 1.8V
1.8V < V
OUT
≤ 3.3V
55
55
55
75
90
90
130
mA
mA
mA
mA
Ground Pin Current in
Shutdown
V
IL
< 0.6V 0.1 5 µA
Current thru V
BIAS
I
L
= 0mA
I
L
= 5.0A
30
70
50
150 mA
mA
Current Limit V
OUT
= 0V 5.5 7.5 9.5 A
Feedback Current 50 1000 nA
Enable Input
Enable Input Threshold Regulator enable
Regulator shutdown
1.6 1.2
1.15
0.6 V
V
Enable Hysteresis 20 50 150 mV
Enable Pin Input Current 0.1 5 µA
Turn-on Time C
OUT
= 10µF; Note 5 10
45 µs
Reference Voltage (Adjustable Output Only)
T
A
= 25°C 0.693 0.7 0.707 V V
REF
–40°C < T
A
< 125°C 0.686 0.714 V
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. Turn-on time is measured from 10% of the positive edge of the enable signal to 90% of the rising edge of the output voltage of the regulator.
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Typical Characteristics
20
25
30
35
40
45
50
55
60
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
LOAD CURRENT (A)
Ground Current
vs. Load Current
V
OUT
= 1.2V
V
EN
= V
IN
V
BIAS
= 3.3V
C
OUT
= 10µF
V
IN
= V
OUT
+ 1V
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
012345
INPUT VOLTAGE (V)
Output Voltage
vs. Input Voltage
50mA
2.5A
5A
V
OUT
= 1.5V
V
BIAS
= 3.3V
C
OUT
= 10µF
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
012345
BIAS VOLTAGE (V)
Output Voltage
vs. Bias Voltage
50mA
2.5A
5A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= C
IN
= 10µF
0
10
20
30
40
50
60
70
80
012345
OUTPUT CURRENT (A)
Bias Current
vs. Output Current
V
IN
= V
OUT
+ 1V
V
OUT
= 1.8V
V
BIAS
= 3.3V
C
OUT
= C
BIAS
= 10µF
0
10
20
30
40
60
20 40 60 80
TEMPERATURE (°C)
Ground Current
vs. Temperature
V
IN
= V
OUT
+ 1V
V
OUT
= 3V
C
OUT
= 10µF
50
2.5A 5A
1A
500mA 100µA
0
1.30
1.35
1.40
1.45
1.50
1.55
1.60
1.65
1.70
Output Voltage
vs. Temperature
20 40 60 80
TEMPERATURE (°C)
V
IN
= V
OUT
= 1V
V
OUT
= 1.5V
C
OUT
= 10µF
0
10
20
30
60
Bias Current
vs. Temperature
20 40 60 80
TEMPERATURE (°C)
V
IN
= 4V
V
OUT
= 3V
C
OUT
= 10µF
40
50
1A
2.5A 5A
0
100µA
500mA
Output Voltage
vs. Temperature
20 40 60 80
TEMPERATURE (°C)
600
620
640
660
680
720
740
760
780
800
700
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 3.3V
C
OUT
= 10µF
I
OUT
= 100µA
0
50
100
150
200
250
300
350
012345
OUTPUT CURRENT (I)
Dropout Voltage
vs. Output Current
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 3.3V
C
OUT
= 10µF
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
012345
OUTPUT CURRENT (A)
V
BIAS
Dropout Voltage
vs. Output Current
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 3.3V
C
OUT
= 10µF
0
0.5
1.0
1.5
2.0
2.5
0 0.5 1 1.5 2 2.5 3
ENABLE VOLTAGE (V)
Enable Threshold
Hot
Room
Cold
0
1
2
3
4
5
6
7
8
9
10
2.5 3 3.5 4 4.5 5 5.5
INPUT VOLTAGE (V)
Current Limit
V
IN
= 2.5V
V
OUT
= 0V
V
BIAS
= 3.3V
C
OUT
= 10µF
vs. Input Voltage
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Typical Characteristics (continued)
0.01
0.1
1
10
1
FREQUENCY (kHz)
Output Noise
Spectral Density
0.10.01 10 100 1,000 10,000
V
IN
= 3.8V
V
OUT
= 2.8V
C
OUT
= 10µF
I
OUT
= 10mA
MIC49500 VBIAS PSRR
RIPPLE REJECTION (dB)
FREQUENCY (Hz)
100
90
80
70
60
50
40
30
20
10
0
10 100 1k 10k 100k 1M
MIC49500 VIN PSRR
RIPPLE REJECTION (dB)
FREQUENCY (Hz)
90
80
70
60
50
40
30
20
10
0
10 100 1k 10k 100k 1M
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July 2007 7
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Functional Characteristics
Enable Turn-On
Enable Volta
g
e
(1V/div)
Output Volta
g
e
(500mV/div)
Time (2µs/div)
V
OUT
= 1.8V
V
IN
= V
BIAS
= 5V
I
OUT
= 10mA
C
OUT
= C
BIAS
= 10µF
C
FEEDFORWARD
= 47pF
Load Transient
Output Volta
g
e
(50mV/div)
Output Current
(2A/div)
Time (10µs/div)
5A
0A
VOUT = 1.8V
VIN = 2.8V
COUT = CBIAS = 10µF
VBIAS = 3.9V
Line Transient (
V
IN)
Input Volta
g
e
(1V/div)
Output Volta
g
e
(10mV/div)
Time (100µs/div)
5V
4V
VOUT = 1.5V
VBIAS = 3.6V
COUT = 10µF
IOUT = 1A
Line Transient (V
BIAS
)
Bias Volta
g
e
(1V/div)
Output Volta
g
e
(20mV/div)
Time (100µs/div)
5V
4V
V
OUT
= 1.5V
V
IN
= 2.5V
C
OUT
= 10µF
I
OUT
= 1A
Micrel, Inc. MIC49500
July 2007 8
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Applications Information
The MIC49500 is an ultra-high performance, low
dropout linear regulator designed for high current
applications requiring fast transient response. The
MIC49500 utilizes two input supplies, significantly
reducing dropout voltage, perfect for low-voltage, DC-
to-DC conversion. The MIC49500 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 MIC49500 regulator is fully protected from
damage due to fault conditions, offering constant
current limiting and thermal shutdown.
Bias Supply Voltage
V
BIAS
, requiring relatively light current, provides power
to the control portion of the MIC49500. V
BIAS
requires
approximately 70mA for 5A load current. 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 290mV
at a 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 V
BIAS
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 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 V
BIAS
input voltage must be 2.1V above
the output voltage with a minimum V
BIAS
input voltage
of 3.0V.
Input Supply Voltage
V
IN
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 MIC49500 requires a minimum of output
capacitance to maintain stability. However, proper
capacitor selection is important to ensure desired
transient response. The MIC49500 is specifically
designed to be stable with a wide range of
capacitance values and ESR. A 10µF 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 (T
A
)
• Output Current (I
OUT
)
• Output Voltage (V
OUT
)
• Input Voltage (V
IN
)
• Ground Current (I
GND
)
First, calculate the power dissipation of the regulator
from these numbers and the device parameters from
this datasheet.
P
D
= V
IN
× I
IN
+ V
BIAS
× I
BIAS
– V
OUT
× I
OUT
The input current will be less than the output current
as the output 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:
SA
=
T
J(MAX)
± T
A
P
D JC CS
)
⎝
⎛
The heat sink may be significantly reduced in
applications 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
Micrel, Inc. MIC49500
July 2007 9
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regulator. The low dropout properties of the MIC49500
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 MIC49500, 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 V
IN
and
V
BIAS
, giving more flexibility to the user.
Adjustable Regulator Design
The MIC49500 adjustable version allows
programming the output voltage anywhere between
0.7Vand 6V. Two resistors are used. The resistor
value between V
OUT
and the adjust pin should not
exceed 10kΩ. Larger values can cause instability. The
resistor values are calculated by:
R1 = R2 ×
V
OUT
0.7 – 1
Where V
OUT
is the desired output voltage.
Enable
The fixed output voltage versions of the MIC49500
feature an active high enable input (EN) that allows
on-off control of the regulator. Current drain reduces
to “zero” when the device is shutdown, with only
microamperes of leakage current. The EN input has
TTL/CMOS compatible thresholds for simple logic
interfacing. EN may be directly tied to V
IN
and pulled
up to the maximum supply voltage.
Micrel, Inc. MIC49500
July 2007 10
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Package Information
7-Pin SPAK (R)
7-Pin TO-263 (U)
Micrel, Inc. MIC49500
July 2007 11
M9999-071307
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
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for
its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a
product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for
surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant
injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk
and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Inc.
