May 15, 2000
1
MIC39300/39301
MIC39300/39301
Micrel
MIC39300/39301
3A Low-Voltage Low-Dropout Regulator
Final Information
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
General Description
The MIC39300 and MIC39301 are 3.0A low-dropout linear
voltage regulators that provide a low voltage, high-current
output with a minimum of external components. Utilizing
Micrel's proprietary Super
eta PNPTM pass element, the
MIC39300/1 offers extremely low dropout (typically 400mV at
3.0A) and low ground current (typically 36mA at 3.0A).
The MIC39300/1 is ideal for PC add-in cards that need to
convert from standard 3.3V to 2.5V or 2.5V to 1.8V. A
guaranteed maximum dropout voltage of 500mV over all
operating conditions allows the MIC39300/1 to provide 2.5V
from a supply as low as 3V, and 1.8V from a supply as low as
2.5V. The MIC39300/1 also has fast transient response for
heavy switching applications. The device requires only 47
F
of output capacitance to maintain stability and achieve fast
transient response
The MIC39300/1 is fully protected with overcurrent limiting,
thermal shutdown, reversed-battery protection, reversed-
leakage protection, and reversed-lead insertion. The
MIC39301 offers a TTL-logic compatible enable pin and an
error flag that indicates under voltage and over current
conditions. Offered in fixed voltages, the MIC39300/1 comes
in the TO-220 and TO-263 packages and is an ideal upgrade
to older, NPN-based linear voltage regulators.
Typical Application
MIC39300-2.5
IN
OUT
GND
47F
V
IN
3.3V
V
OUT
2.5V
MIC39300
Features
3.0A minimum guaranteed output current
500mV maximum dropout voltage over temperature
Ideal for 3.0V to 2.5V conversion
Ideal for 2.5V to 1.8V conversion
1% initial accuracy
Low ground current
Current limiting and Thermal shutdown
Reversed-battery protection
Reversed-leakage protection
Fast transient response
TO-263 and TO-220 packaging
TTL/CMOS compatible enable pin (MIC39301 only)
Error flag output (MIC39301 only)
Applications
LDO linear regulator for PC add-in cards
High-efficiency linear power supplies
SMPS post regulator
Multimedia and PC processor supplies
Low-voltage microcontrollers
StrongARMTM processor supply
StrongARM is a trademark of Advanced RISC Machines, Ltd.
Ordering Information
Part Number
Voltage
Junction Temp. Range
Package
MIC39300-1.8BT
1.8V
40
C to +125
C
3-lead TO-220
MIC39300-1.8BU
1.8V
40
C to +125
C
3-lead TO-263
MIC39301-1.8BT
1.8V
40
C to +125
C
5-lead TO-220
MIC39301-1.8BU
1.8V
40
C to +125
C
5-lead TO-263
MIC39300-2.5BT
2.5V
40
C to +125
C
3-lead TO-220
MIC39300-2.5BU
2.5V
40
C to +125
C
3-lead TO-263
MIC39301-2.5BT
2.5V
40
C to +125
C
5-lead TO-220
MIC39301-2.5BU
2.5V
40
C to +125
C
5-lead TO-263
MIC39301-2.5
IN
OUT
GND
47F
V
IN
3.3V
V
OUT
2.5V
EN
FLG
ERROR FLAG
OUTPUT
ENABLE
SHUTDOWN
100k
MIC39301
MIC39300/39301
Micrel
MIC39300/39301
2
May 15, 2000
Pin Description
Pin Number
Pin Number
Pin Name
Pin Function
MIC39300
MIC39301
1
EN
Enable (Input): TTL/CMOS compatible input. Logic high = enable; logic low
or open = shutdown.
1
2
IN
Unregulated Input: +16V maximum supply.
2,
TAB
3,
TAB
GND
Ground: Ground pin and
TAB
are internally connected.
3
4
OUT
Regulator Output
5
FLG
Error Flag (Ouput): Open-collector indicates an output fault condition.
Active low.
Pin Configuration
TAB
3
OUT
2
GND
1
IN
MIC39300-x.xBT
TO-220-3 (T)
TAB
5
FLG
4
OUT
3
GND
2
IN
1
EN
MIC39301-x.xBT
TO-220-5 (T)
TAB
3
OUT
2
GND
1
IN
MIC39300-x.xBU
TO-263-3 (U)
TAB
5
FLG
4
OUT
3
GND
2
IN
1
EN
MIC39301-x.xBU
TO-263-5 (U)
May 15, 2000
3
MIC39300/39301
MIC39300/39301
Micrel
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
IN
) ..................................... 20V to +20V
Enable Voltage (V
EN
) .................................................. +20V
Storage Temperature (T
S
) ....................... 65
C to +150
C
Lead Temperature (soldering, 5 sec.) ....................... 260
C
ESD, Note 3
Operating Ratings
(Note 2)
Supply Voltage (V
IN
) .................................... +2.5V to +16V
Enable Voltage (V
EN
) .................................................. +16V
Maximum Power Dissipation (P
D(max)
) .................... Note 4
Junction Temperature (T
J
) ....................... 40
C to +125
C
Package Thermal Resistance
TO-263
(
JC
) ......................................................... 2
C/W
TO-220 (
JC
) ......................................................... 2
C/W
Electrical Characteristics
T
J
= 25
C, bold values indicate 40
C
T
J
+125
C; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
V
OUT
Output Voltage
10mA
1
1
%
10mA
I
OUT
3A, V
OUT
+ 1V
V
IN
8V
2
2
%
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
%
V
OUT
/
T
Output Voltage Temp. Coefficient,
20
100
ppm/
C
Note 5
V
DO
Dropout Voltage, Note 6 & 9
I
OUT
= 100mA,
V
OUT
= 1%
65
200
mV
I
OUT
= 750mA,
V
OUT
= 1%
185
mV
I
OUT
= 1.5A,
V
OUT
= 1%
250
mV
I
OUT
= 3A,
V
OUT
= 1%
385
550
mV
I
GND
Ground Current, Note 7
I
OUT
= 750mA, V
IN
= V
OUT
+ 1V
10
20
mA
I
OUT
= 1.5A, V
IN
= V
OUT
+ 1V
17
mA
I
OUT
= 3A, V
IN
= V
OUT
+ 1V
45
mA
I
GND(do)
Dropout Ground Pin Current
V
IN
V
OUT(nominal)
0.5V, I
OUT
= 10mA
6
mA
I
OUT(lim)
Current Limit
V
OUT
= 0V, V
IN
= V
OUT
+ 1V
4.5
A
Enable Input (MIC39301)
V
EN
Enable Input Voltage
logic low (off)
0.8
V
logic high (on)
2.5
V
I
IN
Enable Input Current
V
EN
= 2.5V
15
30
A
75
A
V
EN
= 0.8V
2
A
4
A
I
OUT(shdn)
Shutdown Output Current
Note 8
10
20
A
Flag Output (MIC39301)
I
FLG(leak)
Output Leakage Current
V
OH
= 16V
0.01
1
A
2
A
V
FLG(do)
Output Low Voltage
V
IN
= 2.50V, I
OL
, = 250
A, Note 9
220
300
mV
400
mV
V
FLG
Low Threshold
% of V
OUT
93
%
High Threshold
% of V
OUT
99.2
%
Hysteresis
1
%
MIC39300/39301
Micrel
MIC39300/39301
4
May 15, 2000
Note 1.
Exceeding the absolute maximum ratings 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 circuit layout. See "Applications Information."
Note 5.
Output voltage temperature coefficient is
V
OUT(worst case)
(T
J(max)
T
J(min)
) where T
J(max)
is +125
C and T
J(min)
is 40
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. For output voltages below 2.5V, dropout
voltage is the input-to-output voltage differential with the minimum input voltage being 2.5V. Minimum input operating voltage is 2.5V.
Note 7.
I
GND
is the quiescent current. I
IN
= I
GND
+ I
OUT
.
Note 8.
V
EN
0.8V, V
IN
8V, and V
OUT
= 0V
Note 9.
For a 1.8V device, V
IN
= 2.5V.
May 15, 2000
5
MIC39300/39301
MIC39300/39301
Micrel
Typical Characteristics
0
10
20
30
40
50
1x10
1
1x10
2
1x10
3
1x10
4
1x10
5
1x10
6
PSRR (dB)
FREQUENCY (Hz)
Power Supply
vs. Ripple Rejection
V
OUT
= 2.5V
V
IN
= 3.3V
C
OUT
= 47
F
I
LOAD
= 3A
0
10
20
30
40
50
1x10
1
1x10
2
1x10
3
1x10
4
1x10
5
1x10
6
PSRR (dB)
FREQUENCY (Hz)
Power Supply
vs. Ripple Rejection
V
OUT
= 2.5V
V
IN
= 3.3V
C
OUT
= 100
F
I
LOAD
= 3A
0
50
100
150
200
250
300
350
400
0
1000
2000
3000
DROPOUT VOLTAGE (mV)
OUTPUT CURRENT (mA)
Dropout Voltage
vs. Output Current
V
OUT
= 1.8V
V
OUT
= 2.5V
0
100
200
300
400
500
600
-40 -20 0
20 40 60 80 100 120
DROPOUT VOLTAGE (mV)
TEMPERATURE (
C)
Dropout Voltage
vs. Temperature
I
LOAD
= 3.0A
V
OUT
= 1.8V
V
OUT
= 2.5V
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
1.2
1.6
2.0
2.4
2.8
3.2
3.6
OUTPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Dropout Characteristics
I
LOAD
= 100mA
I
LOAD
= 1.5A
I
LOAD
= 3A
0
10
20
30
40
50
0
1000
2000
3000
GROUND CURRENT (mA)
OUTPUT CURRENT (mA)
Ground Current
vs. Output Current
V
OUT
= 1.8V
V
OUT
= 2.5V
0
2
4
6
8
10
0
2
4
6
8
10
12
GROUND CURRENT (mA)
SUPPLY VOLTAGE (V)
Ground Current
vs. Supply Voltage
I
LOAD
= 10mA
I
LOAD
= 100mA
0
10
20
30
40
50
60
70
80
90
100
0
2
4
6
8
10
12
GROUND CURRENT (mA)
SUPPLY VOLTAGE (V)
Ground Current
vs. Supply Voltage
I
LOAD
=
1000mA
I
LOAD
= 3000mA
I
LOAD
= 1500mA
0
1
2
3
4
5
6
7
8
-40 -20 0
20 40 60 80 100 120
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
LOAD
= 10mA
V
OUT
= 1.8V
V
OUT
= 2.5V
0
5
10
15
20
25
-40 -20 0
20 40 60 80 100 120
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
LOAD
= 1500mA
V
OUT
= 1.8V
V
OUT
= 2.5V
0
10
20
30
40
50
60
-40 -20 0
20 40 60 80 100 120
GROUND CURRENT (mA)
TEMPERATURE (
C)
Ground Current
vs. Temperature
I
LOAD
= 3000A
V
OUT
= 1.8V
V
OUT
= 2.5V
0
1.0
2.0
3.0
4.0
5.0
6.0
-40 -20 0
20 40 60 80 100 120
SHORT CIRCUIT CURRENT (A)
TEMPERATURE (
C)
Short Circuit vs.
Temperature
typical 2.5V device
typical 1.8V device
V
IN
= V
OUT (NOM)
+ 1V
V
OUT
= 0
MIC39300/39301
Micrel
MIC39300/39301
6
May 15, 2000
2.40
2.42
2.44
2.46
2.48
2.50
2.52
2.54
2.56
2.58
2.60
-40 -20 0
20 40 60 80 100 120
ENABLE CURRENT
A)
TEMPERATURE (
C)
Enable Current
vs. Temperature
I
LOAD
= 10mA
typical 2.5V device
0
1
2
3
4
5
6
0.01 0.1
1
10
100 100010000
FLAG VOLTAGE (V)
RESISTANCE (k
)
Error Flag
Pull-Up Resistor
V
IN
= 5V
FLAG HIGH
(OK)
FLAG LOW
(FAULT)
0
2
4
6
8
10
12
-40 -20 0 20 40 60 80 100120140
ENABLE CURRENT
A)
TEMPERATURE (
C)
Enable Current
vs. Temperature
V
IN
= V
OUT
+ 1V
V
EN
= 2.5V
0
50
100
150
200
250
-40 -20 0 20 40 60 80 100120140
FLAG VOLTAGE (mV)
TEMPERATURE (
C)
Flag-Low Voltage
vs. Temperature
V
IN
= 2.5V
R
PULL-UP
= 22k
FLAG-LOW
VOLTAGE
Load Transient
Response
TIME (500
s/div.)
Load Current
(1A/div
.
)
Output V
o
ltage
(200mV/div
.
)
V
IN
= 3.3V
V
OUT
= 2.5V
C
OUT
= 47
F
3A
10mA
Load Transient
Response
TIME (500
s/div.)
Load Current
(1A/div
.
)
Output V
o
ltage
(100mV/div
.
)
V
IN
= 3.3V
V
OUT
= 2.5V
C
OUT
= 100
F
3A
100mA
Line Transient
Response
TIME (100
s/div.)
Input V
o
ltage
(2V/div
.
)
Output V
o
ltage
(50mV/div
.
)
V
OUT
= 2.5V
I
L
= 10mA
C
OUT
= 47
F
5V
3.3V
May 15, 2000
7
MIC39300/39301
MIC39300/39301
Micrel
Functional Diagram
Ref.
18V
O.V.
I
LIMIT
Thermal
Shut-
down
1.240V
1.180V
EN*
IN
FLAG*
GND
OUT
* MIC39301 only
MIC39300/39301
Micrel
MIC39300/39301
8
May 15, 2000
Applications Information
The MIC39300/1 is a high-performance low-dropout voltage
regulator suitable for moderate to high-current voltage regu-
lator applications. Its 500mV dropout voltage at full load
makes it especially valuable in battery-powered systems and
as a high-efficiency noise filter in post-regulator applications.
Unlike older NPN-pass transistor designs, where the mini-
mum dropout voltage is limited by the base-to-emitter voltage
drop and collector-to-emitter saturation voltage, dropout per-
formance of the PNP output of these devices is limited only
by the low V
CE
saturation voltage.
A trade-off for the low dropout voltage is a varying base drive
requirement. Micrel's Super
eta PNPTM process reduces
this drive requirement to only 2% to 5% of the load current.
The MIC39300/1 regulator is fully protected from damage
due to fault conditions. Current limiting is provided. This
limiting is linear; output current during overload conditions is
constant. Thermal shutdown disables the device when the
die temperature exceeds the maximum safe operating tem-
perature. Transient protection allows device (and load) sur-
vival 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.
MIC39300-x.x
IN
OUT
GND
C
IN
C
OUT
V
IN
V
OUT
Figure 1. Capacitor Requirements
Thermal Design
Linear regulators are simple to use. The most complicated
design parameters to consider are thermal characteristics.
Thermal design requires four application-specific param-
eters:
Maximum ambient temperature (T
A
)
Output Current (I
OUT
)
Output Voltage (V
OUT
)
Input Voltage (V
IN
)
Ground Current (I
GND
)
Calculate the power dissipation of the regulator from these
numbers and the device parameters from this datasheet,
where the ground current is taken from the data sheet.
P
D
= (V
IN
V
OUT
) I
OUT
+ V
IN
I
GND
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 signifi-
cant reductions in regulator power dissipation and the asso-
ciated heat sink without compromising performance. When
this technique is employed, a capacitor of at least 1.0
F 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.
Output Capacitor
The MIC39300/1 requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
MIC39300/1 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor
to maintain stability. When the output capacitor is 47
F or
greater, the output capacitor should have less than 1
of
ESR. This will improve transient response as well as promote
stability. Ultralow ESR capacitors, such as ceramic chip
capacitors may promote instability. These very low ESR
levels may cause an oscillation and/or underdamped tran-
sient response. A low-ESR solid tantalum capacitor works
extremely well and provides good transient response and
stability over temperature. Aluminum electrolytics can also
be used, as long as the ESR of the capacitor is < 1
.
The value of the output capacitor can be increased without
limit. Higher capacitance values help to improve transient
response and ripple rejection and reduce output noise.
Input Capacitor
An input capacitor of 1
F or greater is recommended when
the device is more than 4 inches away from the bulk ac supply
capacitance, or when the supply is a battery. Small, surface-
mount, ceramic chip capacitors can be used for the bypass-
ing. Larger values will help to improve ripple rejection by
bypassing the input to the regulator, further improving the
integrity of the output voltage.
Transient Response and 3.3V to 2.5V and 2.5V to 1.8V
Conversions
The MIC39300/1 has excellent transient response to varia-
tions in input voltage and load current. The device has been
designed to respond quickly to load current variations and
input voltage variations. Large output capacitors are not
required to obtain this performance. A standard 47
F output
capacitor, preferably tantalum, is all that is required. Larger
values help to improve performance even further.
By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based de-
signs. When converting from 3.3V to 2.5V or 2.5V to 1.8V, the
NPN-based regulators are already operating in dropout, with
typical dropout requirements of 1.2V or greater. To convert
down to 2.5V without operating in dropout, NPN-based
regulators require an input voltage of 3.7V at the very least.
The MIC39300/1 regulator will provide excellent performance
with an input as low as 3.0V or 2.5V. This gives the PNP-
based regulators a distinct advantage over older, NPN-based
linear regulators.
May 15, 2000
9
MIC39300/39301
MIC39300/39301
Micrel
Minimum Load Current
The MIC39300/1 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.
Error Flag
The MIC39301 version features an error flag circuit which
monitors the output voltage and signals an error condition
when the voltage drops 5% below the nominal output voltage.
The error flag is an open-collector output that can sink 10mA
during a fault condition.
Low output voltage can be caused by a number of problems,
including an overcurrent fault (device in current limit) or low
input voltage. The flag is inoperative during overtemperature
shutdown.
When the error flag is not used, it is best to leave it open. The
flag pin can be tied directly to pin 4, the output pin.
Enable Input
The MIC39301 version features an enable input for on/off
control of the device. Its shutdown state draws "zero" current
(only microamperes of leakage). The enable input is TTL/
CMOS compatible for simple logic interface, but can be
connected to up to 20V. When enabled, it draws approxi-
mately 15
A.
MIC39300/39301
Micrel
MIC39300/39301
10
May 15, 2000
Package Information
0.018
0.008
(0.46
0.020)
0.100
0.005
(2.54
0.13)
0.030
0.003
(0.76
0.08)
0.050
0.003
(1.27
.08)
7
1.140
0.010
(28.96
0.25)
0.356
0.005
(9.04
0.13)
0.590
0.005
(14.99
0.13)
0.108
0.005
(2.74
0.13)
0.050
0.005
(1.27
0.13)
0.151 D
0.005
(3.84 D
0.13)
0.410
0.010
(10.41
0.25)
0.176
0.005
(4.47
0.13)
0.100
0.020
(2.54
0.51)
0.818
0.005
(20.78
0.13)
7
3
DIMENSIONS: INCH
(MM)
3-Lead TO-220 (T)
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-220-5 (T)
May 15, 2000
11
MIC39300/39301
MIC39300/39301
Micrel
0.360
0.005
0.600
0.025
0.405
0.005
0.100 BSC
0.050
0.050
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
3-Lead TO-263 (U)
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-263-5 (U)
MIC39300/39301
Micrel
MIC39300/39301
12
May 15, 2000
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.
2000 Micrel Incorporated
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