MIC37150/51/52/53
1.5A, Low Voltage µCap LDO Regulator
Super ßeta PNP is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (
408
) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 2007
M9999-061507
General Description
The Micrel MIC37150/51/52/53 is a 1.5A low-dropout
linear voltage regulator that provides a low voltage, high
current output with a minimum of external components. It
offers high precision, ultra-low dropout (500mV over
temperature), and low ground current.
The MIC37150/51/52/53 operates from an input of 2.25V
to 6.0V. It is designed to drive digital circuits requiring low
voltage at high currents (i.e., PLDs, DSPs, micro-
controllers, etc.). It is available in fixed and adjustable
output voltages. Fixed voltages include 1.5V, 1.65V, 1.8V,
2.5V and 3.3V. The adjustable version is capable of
supplying output voltages from 1.24V to 5.5V.
Features of the MIC37150/51/52/53 LDO include thermal
and current limit protection, and reverse current and
reverse battery protection. Logic enable and error flag pins
are available.
Junction temperature range of the MIC37150/51/52/53 is
from –40°C to +125°C.
For applications requiring input voltage greater than 6.0V,
see MIC3910x, MIC3915x, MIC3930x, and MIC3950x
LDOs.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• 1.5A 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, 1.65V, or 1.5V conversion
• Stable with ceramic or tantalum capacitor
• Wide input voltage range
– VIN: 2.25V to 6.0V
• ±1.0% initial output tolerance
• Fixed and adjustable output voltages
– MIC37150—3-pin fixed voltages
– MIC37151—5-pin S-Pak or 8-pin e-Pad SOIC
fixed voltages with flag
– MIC37152—5-pin adjustable voltage
– MIC37153—8-pin adjustable voltage with flag
• Excellent line and load regulation specifications
• Logic controlled shutdown
• Thermal shutdown and current limit protection
• Reverse-leakage protection
• Low profile 3 or 5-pin S-Pak packages or 8-pin e-Pad
SOIC
Applications
• LDO linear regulator for low-voltage digital IC
• PC add-in cards
• High efficiency linear power supplies
• SMPS post regulator
• Battery charger
Typical Application
VOUTVIN
FLG
GND
VEN
C
OUT
47µF, Ceramic
100k
MIC37151
V
IN
= 3.0V V
OUT
= 2.5V
C
IN
VOUTVIN
ADJ
GND
VEN
C
OUT
47µF, Ceramic
R1
R2
1.3V
MIC37152
V
IN
C
IN
Fixed 2.5V Regulato r w ith Error Flag
Adjustable Regulator
Micrel, Inc. MIC37150/51/52/53
June 2006 2 M9999-061507
Ordering Information
Part Number
Standard RoHS Compliant* /
Pb-free
Output
Current Voltage Junction Temp. Range Package
MIC37150-1.5BR MIC37150-1.5WR* 1.5A 1.5V –40° to +125°C S-PAK-3
MIC37150-1.65BR MIC37150-1.65WR* 1.5A 1.65V –40° to +125°C S-PAK-3
MIC37150-1.8BR MIC37150-1.8WR* 1.5A 1.8V –40° to +125°C S-PAK-3
MIC37150-2.5BR MIC37150-2.5WR* 1.5A 2.5V –40° to +125°C S-PAK-3
MIC37150-3.3BR MIC37150-3.3WR* 1.5A 3.3V –40° to +125°C S-PAK-3
MIC37151-1.5BR MIC37151-1.5WR* 1.5A 1.5V –40° to +125°C S-PAK-5
MIC37151-1.5YME 1.5A 1.5V –40° to +125°C e-Pad SOIC-8
MIC37151-1.65BR MIC37151-1.65WR* 1.5A 1.65V –40° to +125°C S-PAK-5
MIC37151-1.8YME 1.5A 1.8V –40° to +125°C e- Pad SOIC-8
MIC37151-1.8BR MIC37151-1.8WR* 1.5A 1.8V –40° to +125°C S-PAK-5
MIC37151-2.5YME 1.5A 2.5V –40° to +125°C e-Pad SOIC-8
MIC37151-2.5BR MIC37151-2.5WR* 1.5A 2.5V –40° to +125°C S-PAK-5
MIC37151-3.3BR MIC37151-3.3WR* 1.5A 3.3V –40° to +125°C S-PAK-5
MIC37152BR MIC37152WR* 1.5A ADJ –40° to +125°C S-PAK-5
MIC37152YM 1.5A ADJ –40° to +125°C SOIC-8
MIC37153YME 1.5A ADJ –40° to +125°C e-Pad SOIC-8
* RoHS compliant with ‘high-melting solder’ exemption.
Micrel, Inc. MIC37150/51/52/53
June 2006 3 M9999-061507
Pin Configur ation
TAB
3 VOU
T
2 GND
1 VIN
TAB
5 FLG/AD
J
4 VOUT
3 GND
2 VIN
1EN
S-PAK-3 (R)
S-PAK-5 (R)
1EN
VIN
V
OUT
ADJ
8 GND
GND
GND
GND
7
6
5
2
3
4
1GND
EN
VIN
NC
8 FLG
VOUT/ADJ
VOUT
NC
7
6
5
2
3
4
SOIC-8 (M)
e-Pad SOIC-8 (ME)
Pin Description
Pin Number
S-PAK-3 Pin Number
S-PAK-5
Pin Number
SOIC-8
Pin Number
e-Pad SOIC-8
Pin Name Pin Name
– 1 1 2 EN
Enable (Input): CMOS compatible input.
Logic high = enable, logic low = shutdown.
1 2 2 3 VIN
Input voltage which supplies current to the output
power device.
2 3 5, 6, 7, 8 1 GND Ground (TAB is connected to ground on S-Pak)
6, 7 (Fixed)
3 4 3
6 (Adj)
VOUT Regulator Output
– 8 FLG
Error Flag (Output): Open collector output.
Active low indicates an output fault condition.
– 5
4 7 ADJ
Adjustable regulator feedback input.
Connect to resistor voltage divider.
– – – 4, 5 NC Not internally connected.
Micrel, Inc. MIC37150/51/52/53
June 2006 4
M9999-061507
Absolute Maximum Ratings(1)
Supply Voltage (V
IN
)......................................................6.5V
Enable Input Voltage (V
EN
)............................................6.5V
Power Dissipation .....................................Internally Limited
Junction Temperature .........................–40°C ≤ T
J
≤ +125°C
Storage Temperature (T
s
) ...................–65°C ≤ T
J
≤ +150°C
Lead Temperature (soldering, 5sec.)......................... 260°C
EDS Rating................................................................ Note 3
Operating Ratings(2)
Supply voltage (V
IN
) ....................................... 2.25V to 6.0V
Enable Input Voltage (V
EN
).................................. 0V to 6.0V
Junction Temperature Range .............–40°C ≤ T
J
≤ +125°C
Maximum Power Dissipation..................................... Note 4
Package Thermal Resistance
S-Pak (θ
JC
) ..........................................................2°C/W
Power SOIC-8 (θ
JA
) ...........................................63°C/W
e-Pad SOIC-8 (θ
JC
)............................................10°C/W
Electrical Characteristics(5)
T
A
= 25°C with V
IN
= V
OUT
+ 1V; V
EN
= V
IN
; bold values indicate –40°C < T
J
< +125°C, unless otherwise noted.
Parameter Condition Min Typ Max Units
I
L
= 10mA –1 +1 % Output Voltage Accuracy
10mA < I
OUT
< I
L(max)
, V
OUT
+ 1 ≤ V
IN
≤ 6V –2 +2 %
Output Voltage Line Regulation V
IN
= V
OUT
+1.0V to 6.0V 0.06 0.5 %
Output Voltage Load Regulation I
L
= 10mA to 1.5A 0.2 1 %
I
L
= 750mA 350 mV
V
IN
– V
OUT
; Dropout Voltage,
Note 6 I
L
= 1.5A 500 mV
Ground Pin Current, Note 7 I
L
= 1.5A 17 30 mA
Ground Pin Current in Shutdown V
IL
≤ 0.5V, V
IN
= V
OUT
+ 1V 1.0 µA
Current Limit V
OUT
= 0 2.25 4.0 A
Start-up Time V
EN
= V
IN
, I
OUT
= 10mA, C
OUT
= 22µF 170 500 µs
Enable Input
Regulator enable 2.25 V Enable Input Threshold
Regulator shutdown 0.8 V
V
IL
≤ 0.8V (regulator shutdown) 2
4
µA
µA
Enable Pin Input Current
V
IH
≥ 2.25V (regulator enabled) 1 15 30
75
µA
µA
Flag Output
I
FLG(LEAK)
V
OH
= 6V 1
2
µA
µA
V
FLG(LO)
V
IN
= 2.25V, I
OL
= 250µA, Note 8 210
300
400
mV
mV
Low threshold, % of V
OUT
below nominal 93 %
Hysteresis 2 %
V
FLG
High threshold, % of V
OUT
below nominal 99.2 %
1.228 1.240 1.252 V Reference Voltage
Note 9 1.215 1.265 V
Reference Voltage Temp.
Coefficient
Note 10 20 ppm/°C
Adjust Pin Bias Current 40 80
120
nA
nA
Adjust Pin Bias Current Temp.
Coefficient
0.1 nA/°C
Micrel, Inc. MIC37150/51/52/53
June 2006 5
M9999-061507
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.
4. P
D(MAX)
= (T
J(MAX)
– T
A
) / θ
JA
, where θ
JA
, depends upon the printed circuit layout. See “Applications Information.”
5. Specification for packaged product only.
6. V
DO
= V
IN
– V
OUT
when V
OUT
decreased to 98% of its nominal output voltage with V
IN
= V
OUT
+1V. For output voltages below 1.75V, dropout voltage
specification does not apply due to a minimum input operating voltage of 2.25V.
7. I
IN
is the quiescent current. I
IN
= I
IN
+ I
OUT
.
8. For a 2.5V device, V
IN
= 2.250V (device is in dropout).
9. V
REF
≤ V
OUT
≤ (V
IN
–1.0V), 2.25V ≤ V
IN
≤ 6.0V, 10mA ≤ I
L
≤ 1.5A, T
J
= T
MAX
.
10. Thermal regulation is defined as the change in output voltage at a time t after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 200mA load pulse at V
IN
= 6V for t = 10ms.
Micrel, Inc. MIC37150/51/52/53
June 2006 6
M9999-061507
Typical Characteristics
0
20
40
60
80
1E-2 1E-1 1E+0 1E+1 1E+2 1E+3
)Bd(RRSP
FREQUENCY (Hz)
Power Suppl
y
Rejection Ratio
I
OUT
= 1.5A
C
OUT
= 10µF
C
IN
= 0
V
IN
= 3.3V
V
OUT
= 2.5V
0.01 0.1 110
100 1k
0
50
100
150
200
250
300
350
400
450
500
-40 -20 0 20 40 60 80 100 120
)Vm(EGATLOVTUOPORD
TEMPERATURE (°C)
Dropout Voltage vs.
Temperature
2.5V
OUT
0
5
10
15
20
25
30
35
40
45
0123456
)Am(TNERRUCDNUORG
SUPPLY VOLTAGE (V)
Ground Current
vs. Supply Voltage
V
OUT
= 2.5V
1500mA
750mA
1000mA
0.4
0.405
0.41
0.415
0.42
0.4
0.43
0.435
0.44
0.445
0.5
-40-200 20406080100120
)Am(TNERRUCDNUORG
TEMPERATURE (°C)
Ground Current
vs. Temper ature
V
OUT
= 2.5V
I
LOAD
= 10mA
0
1
2
3
4
5.0
6
7
-40 -20 0 20 40 60 80 100 120
)Am(TNERRUCDNUORG
TEMPERATURE (°C)
Ground Current
vs. Temper atu re
V
OUT
= 2.5V
I
LOAD
= 750mA
Micrel, Inc. MIC37150/51/52/53
June 2006 7
M9999-061507
0
50
100
150
200
250
-40-20 0 20406080100120
)Vm(EGATLOVGALF
TEMPERATURE (°C)
Flag-Low Voltag
e
vs. Temperature
V
IN
= 2.25V
R
PULL-UP
= 22k
0
1
2
3
4
5
6
0.01 0.1 1 10 100 100010000
)V(EGATLOVGALF
RESISTANCE (k )
Error Flag
Pull-Up Resistor
V
IN
= 5V
FLAG HIGH
(OK)
FLAG LOW
(FAULT)
Micrel, Inc. MIC37150/51/52/53
June 2006 8
M9999-061507
Functional Characteristics
TIME (250µs/div.)
EGATLOVTUPNI
).vid/V2(
EGATLOVTUPTUO
).vid/Vm02(
V
OUT
= 2.5V
C
OUT
= 10µF
Line Transient Response
3.3V
5V
Micrel, Inc. MIC37150/51/52/53
June 2006 9
M9999-061507
Application Information
The MIC37150/51/52/53 is a high-performance low-
dropout voltage regulator suitable for moderate to high-
current regulator applications. Its 500mV dropout voltage
at full load and over-temperature makes it especially
valuable in battery-powered systems and as high-
efficiency noise filters in post-regulator applications.
Unlike older NPN-pass transistor designs, there the
minimum dropout voltage is limited by the based-to-
emitter voltage drop and collector-to-emitter saturation
voltage, dropout performance 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 ßeta PNP™ process
reduces this drive requirement to only 2% to 5% of the
load current.
The MIC37150/51/52/53 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 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.
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
– V
OUT
) I
OUT
+ V
IN
I
GND
Where the ground current is approximated by using
numbers from the “Electrical Characteristics” or “Typical
Characteristics.” Then, the heat sink thermal resistance
is determined with this formula:
θ
SA
= ((T
J(MAX)
– T
A
)/ P
D
) – (θ
JC
+ θ
CS
)
Where T
J(MAX)
≤ 125°C and θ
CS
is between 0°C 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
ßeta PNP™ regulators 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 1.0µF 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 applications.
Output Capacitor
The MIC37150/51/52/53 requires an output capacitor for
stable operation. As a µCap LDO, the
MIC37150/51/52/53 can operate with ceramic output
capacitors as long as the amount of capacitance is 47µF
or greater. For values of output capacitance lower than
47µF, the recommended ESR range is 200mΩ to 2Ω.
The minimum value of output capacitance recommended
for the MIC37151 is 10µF.
For 47µF or greater, the ESR range recommended is
less than 1Ω. Ultra-low ESR ceramic capacitors are
recommended for output capacitance of 47µF or greater
to help improve transient response and noise reduction
at high frequency. X7R/X5R dielectric-type 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 capacitor to ensure
the same minimum capacitance over the equivalent
operating temperature range. The MIC37150/51/52/53
has excellent transient response to variations 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 47µF
output capacitor, is all that is required. Larger values
help to improve performance even further.
Input Capacitor
An input capacitor of 1.0µF or greater is recommended
when the device is more than 4 inches away from the
bulk and supply capacitance, or when the supply is a
battery. Small, surface-mount chip capacitors can be
used for the bypassing. The capacitor should be place
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.
Transient Response and 3.3V to 2.5V, 2.5V to 1.8V or
1.65V, or 2.5V to 1.5V Conversions
The MIC37150/51/52/53 has excellent transient
response to variations in input voltage and load current.
The device has been designed to respond quickly to
Micrel, Inc. MIC37150/51/52/53
June 2006 10
M9999-061507
load current variations and input voltage variations.
Large output capacitors are not required to obtain this
performance. A standard 10µF 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
designs. When converting from 3.3V to 2.5V, 2.5V to
1.8V or 1.65V, or 2.5V to 1.5V, 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 MIC37150/51/52/53 regulator will provide
excellent performance with an input as low as 3.0V or
2.25V, respectively. This gives the PNP-based
regulators a distinct advantage over older, NPN-based
linear regulators.
Minimum Load Current
The MIC37150/51/52/53 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 operation.
Error Flag
The MIC37151 and MIC37153 feature an error flag
circuit that monitors the output voltage and signals an
error condition when the voltage 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.
Enable Input
The MIC37151/37152/37153 also 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 V
IN
. When
enabled, it draws approximately 15µA.
Adjustable Regulator Design
IN
R1
V
OUT
V
IN
C
OUT
R2
EN
OUT
ADJ
GND
MIC37152
ENABLE
SHUTDOWN
V
OUT
= 1.240V (1 + )
R1
R2
Figure 1. Adjustable Regu lato r with Resistors
The MIC37152 and MIC37153 allow programming the
output voltage anywhere between 1.24V and the 5.5V
maximum operating rating of the family. Two resistors
are used. Resistors can be quite large, up to 1MΩ,
because of the very high input impedance and low bias
current of the sense comparator: The resistor values are
calculated by:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−= 1
1.240
V
R2R1
OUT
Where V
OUT
is the desired output voltage. Figure 1
shows component definition. Applications with widely
varying load currents may scale the resistors to draw the
minimum load current required for proper operation (see
above).
Micrel, Inc. MIC37150/51/52/53
June 2006 11
M9999-061507
Package Information
3-Pin S-PAK (R)
5-Pin S-PAK (R)
Micrel, Inc. MIC37150/51/52/53
June 2006 12
M9999-061507
8-Pin SOIC (M)
8-Pin SOIC (ME)
Micrel, Inc. MIC37150/51/52/53
June 2006 13
M9999-061507
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.
© 2003 Micrel, Incorporated.
