MIC49200
2A Low Voltage LDO
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 2006
M9999-011306
(408) 955-1690
General Description
The MIC49200 is a high-bandwidth, low-dropout, 2A
voltage regulator ideal for powering core voltages of low-
power microprocessors. The MIC49200 implements a
dual supply configuration allowing for very low output
impedance and very fast transient response.
The MIC49200 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 MIC49200 offers fixed output
voltages from 0.9V to 1.8V and adjustable output voltages
down to 0.9V.
The MIC49200 requires a minimum of output capacitance
for stability, working optimally with small ceramic
capacitors.
The MIC49200 is available in a 5-pin S-Pak. Its operating
temperature range is –40°C to +125°C.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• Input Voltage Range:
V
IN
: 1.4V to 6.5V
V
BIAS
: 3.0V to 6.5V
• Stable with 1µF ceramic output capacitors
• ±1% initial tolerance
• Maximum dropout voltage (V
IN
–V
OUT
) 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
• Junction temperature range: –40°C to 125°C
Applications
• Set-top box
• Graphics processors
• PC add-in cards
• Microprocessor core voltage supply
• Low voltage digital ICs
• High efficiency linear power supplies
• SMPS post regulators
Typical Application
Low Voltage, Fast Transient Response Regulator
Load Transient
Output Voltage
(50mV/div)
Output Current
(1A/div)
Time (40µs/div)
V
IN
= 2.8V
V
OUT
= 1.8V
V
BIAS
= 4V
C
OUT
= 1µF
Micrel, Inc. MIC49200
January 2006
2 M9999-011306
(408) 955-1690
Ordering Information
Part Number
RoHS Compliant Output
Current Voltage Junction
Temperature Range Package
MIC49200-1.0WR* 2A
1.0V –40°C to +125°C S-Pak-5
MIC49200-1.8WR* 2A
1.8V –40°C to +125°C S-Pak-5
MIC49200WR* 2A
Adj –40°C to +125°C S-Pak-5
* RoHS compliant with ‘high-melting solder’ exemption.
Pin Configur ation
5-Pin S-Pak (R)
Pin Description
Pin Number
S-Pak-5 Pin Name
Pin Function
EN Enable (Input): CMOS compatible input. Logic High = enable; Logic Low =
shutdown.
1
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 which supplies current to the output power device.
5 VOUT Regulator Output.
Micrel, Inc. MIC49200
January 2006
3 M9999-011306
(408) 955-1690
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
) ................................................ 8V
Bias Supply Voltage (V
BIAS
) ..................................... 8V
Enable Input Voltage (V
EN
)...................................... 8V
Power Dissipation............................. Internally Limited
ESD Rating
(3)
.........................................................3kV
Operating Ratings(2)
Supply voltage (V
IN
)....................................1.4V to 6.5V
Bias Supply Voltage (V
BIAS
)...........................3V to 6.5V
Enable Input Voltage (V
EN
)............................0V to 6.5V
Junction Temperature ...................-40°C ≤ T
J
≤ +125°C
Package Thermal Resistance
S-Pak (θ
JA
) ................................................. 2°C/W
Electrical Characteristics(4)
T
A
= 25°C with V
BIAS
= V
OUT
+ 2.2V; V
IN
= V
OUT
+ 1V; bold values indicate –40°C ≤ T
J
≤ +125°C
(5)
, unless noted.
Parameter Conditions Min Typ Max Units
Output Voltage Accuracy
At 25°C
Over temperature range (I
OUT
= 10mA)
-1
-2
+1
+2
%
%
Line Regulation V
IN
= V
OUT
+ 1V to 6.5V -0.1 0.01 +0.1 %/V
Load Regulation I
L
= 10mA to 2A 0.2 1
1.5 %
%
Dropout Voltage (V
IN
– V
OUT
)
(Note 5)
I
L
= 750mA
I
L
= 1.5A
I
L
= 2A
130
280
400
200
300
400
500
530
625
mV
mV
mV
mV
mV
mV
Dropout Voltage (V
BIAS
– V
OUT
)
(Note 5)
I
L
= 750mA
I
L
= 1.5A
I
L
= 2A
1.3
1.65
1.75
1.9
2.1
2.0
2.2
V
V
V
V
V
Ground Current (No t e 6) I
L
= 0mA
I
L
= 2A
15
15
25
30
mA
mA
mA
Ground Pin Current in Shutdown V
EN
≤ 0.6V, (V
BIAS
+ I
INPUT
) (Note 7) 0.5 1
2
µA
µA
Current thru V
BIAS
I
L
= 0mA
I
L
= 2A
9
40
15
25
120
mA
mA
mA
Current Limit V
OUT
= 0V 2.5 3.5 5.3
6
A
A
Enable Input Threshold Regulator enable
Regulator shutdown
1.6
0.6
V
V
Enable Pin Input Current Independent of state 0.1 1 µA
Reference
Reference Voltage Adjustable version 0.891
0.882
0.9 0.909
0.918
V
V
Micrel, Inc. MIC49200
January 2006
4 M9999-011306
(408) 955-1690
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating range.
3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4. Specification for packaged product only.
5. For V
OUT
≤ 1.1V, V
BIAS
dropout specification does not apply due to a minimum 3V V
BIAS
input. Dropout voltage is defined as the input-to-output
differential at which the output voltage drops 2% below its nominal value measured at 1V differential for V
IN
and 2.2V differential for V
BIAS
.
For outputs below 1.4V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 1.4V.
6. I
GND
= I
BIAS
+ (I
IN
– I
OUT
). At high loads, input current on V
IN
will be less then the output current, due to drive current being supplied by V
BIAS
.
7. Fixed output voltage versions only.
Micrel, Inc. MIC49200
January 2006
5 M9999-011306
(408) 955-1690
Functional Diagram
V
OUT
Enable Bandgap
V
BIAS
V
IN
Ilimit
R1
R2
Fixed
Adj.
Fixed
V
EN
/
ADJ
Micrel, Inc. MIC49200
January 2006
6 M9999-011306
(408) 955-1690
Typical Characteristics
0
20
40
60
80
100
120
Power Supply Rejection Ratio
(Input Supply)
1
FREQUENCY (kHz)
0.10.01 10 100 1,000
2A
100mA
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 4V
C
OUT
= 1µF
0
20
40
60
80
Power Supply Rejection Ratio
(Bias Supply)
1
FREQUENCY (kHz)
0.10.01 10 1,000100
2A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 4V
C
OUT
= 1µF
I
OUT
= 2A
0
50
100
150
200
250
300
350
400
450
1200 1600 2000
OUTPUT CURRENT (mA)
Dropout Voltage
(Input Supply)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Dropout Voltage
(Bias Supply)
1200 1600 2000
OUTPUT CURRENT (mA)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0
TEMPERATURE (°C)
Dropout Voltage
vs. Temperature
(Input Supply)
400
450
500
550
50
100
150
200
250
300
350
V
IN
= V
OUT
+1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
I
OUT
= 100mA
I
OUT
= 1A
I
OUT
= 2A
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
2.0
TEMPERATURE (°C)
Dropout Voltage
vs. Temperature
(Bias Supply)
1.8
1.6
I
OUT
= 2A
I
OUT
= 100mA
I
OUT
= 1A
V
IN
= V
OUT
+1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0
0123456
INPUT VOLTAGE (V)
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Dropout Characteristics
(Input Supply)
V
BIAS
= 5V
V
OUT
= 1.5V
C
OUT
= 1µF
2A
10mA
0
0123456
BIAS VOLTAGE (V)
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Dropout Characteristics
(Bias Supply)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
2A
10mA
1.46
1.47
1.48
1.49
1.50
1.51
1.52
OUTPUT CURRENT (A)
Load Regulation
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
Output Voltage
vs. Temperature
TEMPERATURE (°C)
1.20
1.25
1.30
1.35
1.40
1.45
1.55
1.60
1.65
1.70
1.75
1.80
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
1.50
0
50
100
150
200
250
300
3 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Maximum Bias Current
vs. Bias Voltage
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
I
OUT
= 2A
C
OUT
= 1µF
V
ADJ
= 0V
0
50
100
150
200
250
300
Maximum Bias Current
vs. Temperature
TEMPERATURE (°C)
I
BIAS
V
IN
= V
OUT
+1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
V
ADJ
= 0V
Micrel, Inc. MIC49200
January 2006
7 M9999-011306
(408) 955-1690
0
5
10
15
20
25
30
35
40
45
50
Bias Current
vs. Temperature
TEMPERATURE (°C)
I
OUT
= 100mA
I
OUT
= 1.5A
I
OUT
= 2A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0
10
20
30
40
50
Bias Current
vs. Output Current
1200 1600 2000
OUTPUT CURRENT (A)
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
Ground Current
vs. Input Voltage
1.5 2.5 3.5 4.5 5.5 6.5
I
OUT
=0A
V
BIAS
= V
OUT
+ 2.1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
2
4
6
8
10
12
14
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Ground Current
vs. Bias Voltage
I
OUT
= 0A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
2
4
6
8
10
12
14
3 3.5 4 4.5 5 5.5 6 6.5
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
=0A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
2
4
6
8
10
12
14
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 100mA
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
10
20
30
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 750mA
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
10
20
30
40
50
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 1.5A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
10
20
30
40
50
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Bias Current
vs. Bias Voltage
I
OUT
= 2A
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
2
4
6
8
10
12
14
16
18
20
0 0.5 1.0 1.5 2.0 2.5
INPUT VOLTAGE (V)
Bias Current
vs. Input Voltage
100mA
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
0mA
0
50
100
150
200
250
300
0 0.5 1.0 1.5 2.0 2.5
INPUT VOLTAGE (V)
Bias Current
vs. Input Voltage
750mA
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
2A
0.899
0.901
Reference Voltage
vs. Input Voltage
1.5 2.5 3.5 4.5 5.5 6.5
INPUT VOLTAGE (V)
0.900
V
OUT
= 1.5V
V
BIAS
= 5V
C
OUT
= 1µF
Micrel, Inc. MIC49200
January 2006
8 M9999-011306
(408) 955-1690
0.899
0.900
0.901
3 3.5 4 4.5 5 5.5 6 6.5
BIAS VOLTAGE (V)
Reference Voltage
vs. Bias Voltage
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Short Circuit Current
vs. Temperature
TEMPERATURE (°C)
V
IN
= V
OUT
+ 1V
V
OUT
= 1V
V
BIAS
= 5V
C
OUT
= 1µF
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
BIAS VOLTAGE (V)
Enable Threshold
vs. Bias Voltage
OFF
ON
V
IN
= V
OUT
+ 1V
V
OUT
= 1V
C
OUT
= 1µF
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Enble Threshold
vs. Temperature
OFF
ON
V
IN
= V
OUT
+ 1V
V
OUT
= 1V
V
BIAS
= 5V
C
OUT
= 1µF
TEMPERATURE (°C)
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1.5 2.5 3.5 4.5 5.5 6.5
INPUT VOLTAGE (V)
Current Limit
vs. Input Voltage
V
BIAS
= 3.3V
C
OUT
= 1µF
V
OUT
= 1.5V
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
23456
BIAS VOLTAGE (V)
Current Limit
vs. Bias Voltage
V
IN
= V
OUT
+ 1V
V
OUT
= 1.5V
C
OUT
= 1µF
Micrel, Inc. MIC49200
January 2006
9 M9999-011306
(408) 955-1690
Functional Characteristics
Line Transient (
V
IN
)
Output Volta
g
e
(20mV/div)
Input Volta
g
e
(2V/div)
Time (100µs/div)
V
OUT
= 1.5V
V
BIAS
= 3.3V
C
OUT
= 1µF
I
OUT
= 2A
V
IN
= 3.3V
V
IN
= 5V
Line Transient (
V
BIAS
)
Output Volta
g
e
(20mV/div)
Bias Voltage
(2V/div)
Time (20µs/div)
V
IN
= 2.8V
V
OUT
= 1.8V
C
OUT
= 1µF
I
OUT
= 2A
V
BIAS
= 4V
V
BIAS
= 6V
Enable Turn-On
Enable
(2V/div)
Output Volta
g
e
(1V/div)
Time (4µs/div)
VIN = VOUT + 1V
VOUT = 1.8V
VBIAS = 4V
COUT = 1µF
Load Transient
Output Voltage
(50mV/div)
Output Current
(1A/div)
Time (40µs/div)
V
IN
= 2.8V
V
OUT
= 1.8V
V
BIAS
= 4V
C
OUT
= 1µF
Micrel, Inc. MIC49200
January 2006
10 M9999-011306
(408) 955-1690
Applications Information
The MIC49200 is an ultra-high performance, low-
dropout linear regulator designed for high current
applications requiring fast transient response. The
MIC49200 utilizes two input supplies, significantly
reducing dropout voltage, perfect for low-voltage, DC-
to-DC conversion. The MIC49200 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
type and tantalum type capacitors.
The MIC49200 regulator is fully protected from
damage due to fault conditions, offering linear current
limiting and thermal shutdown.
Bias Supply Voltage
V
BIAS
, requiring relatively light current, provides power
to the control portion of the MIC49200. V
BIAS
requires
approximately 40mA 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 thereby reducing the dropout to 400mV
at a 2A 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 represent 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 volts.
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 MIC49200 requires a minimum of output
capacitance to maintain stability. However, proper
capacitor selection is important to ensure desired
transient response. The MIC49200 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 Characteristic”
subsection 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" 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
As the load increases, the input current will be less
than the output current at high output currents. The
bias current is a sum of base drive and ground
current. Ground current is constant over load current.
The heat sink thermal resistance is determined with
this formula:
D
AJ(MAX)
SA P
TT
θ
−
=
Micrel, Inc.
MIC49200
January 2006
11 M9999-011306
(408) 955-1690
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
regulator. The low-dropout properties of the
MIC49200 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 MIC49200, unlike most other high current
regulators, does not require a minimum load to
maintain output voltage regulation.
Adjustable Regulator Design
The MIC49200 adjustable version allows
programming the output voltage anywhere between
0.9V and 5V. 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:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛+= 1
R
R
0.9 V
2
1
OUT
Where V
OUT
is the desired output voltage.
Enable
The fixed output voltage versions of the MIC49200
feature an active high enable input (EN) that allows
on-off control of the regulator. Supply currents reduce
to “zero” when the device is in 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.
MIC49200
January 2006 12
M9999-011306
(408) 955-1690
Package Information
5-Pin S-Pak (R)
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.
