MIC5252 Micrel, Inc.
February 2005 1 M9999-020305
General Description
The MIC5252 is an efficient, precise CMOS voltage regulator
optimized for ultra-low-noise applications. It offers 1% initial
accuracy, extremely-low dropout voltage (135mV at 150mA)
and low ground current (typically 90µA). The MIC5252
provides a very-low-noise output, ideal for RF applications
where a clean voltage source is required. The MIC5252 has
a high PSRR even at low supply voltages, critical for battery
operated electronics. A noise bypass pin is also available for
further reduction of output noise.
Designed specifically for handheld and battery-powered
devices, the MIC5252 provides a TTL-logic-compatible en-
able pin. When disabled, power consumption drops nearly
to zero.
The MIC5252 also works with low-ESR ceramic capacitors,
reducing the amount of board space necessary for power
applications, critical in handheld wireless devices.
Key features include current limit, thermal shutdown, faster
transient response, and an active clamp to speed up device
turn-off. The MIC5252 is available in the 6-pin 2mm × 2mm
MLF™ package and the IttyBitty® SOT-23-5 package in a
wide range of output voltages.
Typical Application
COUT = 1.0µF
CIN = 1.0µF
Ceramic
Ceramic
1 5
2
34
CBYP = 0.01µF
Enable
Shutdown EN
VOUT
MIC5252-x.xBM5
EN (pin 3) may be
connected directly
to IN (pin 1).
VIN
MIC5252
150mA High PSRR, Low Noise µCap CMOS LDO
Features
• Input voltage range: 2.7V to 6.0V
• PSRR = 50dB @ VO + 0.3V
• Ultra-low output noise: 30µV(rms)
• Stability with ceramic output capacitors
• Ultra-low dropout: 135mV @ 150mA
• High output accuracy:
1.0% initial accuracy
2.0% over temperature
• Low quiescent current: 90µA
• Tight load and line regulation
• TTL-Logic-controlled enable input
• “Zero” off-mode current
• Thermal shutdown and current limit protection
Applications
• Cellular phones and pagers
• Cellular accessories
• Battery-powered equipment
• Laptop, notebook, and palmtop computers
• Consumer/personal electronics
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
IttyBitty is a registered trademark of Micrel, Inc.
MicroLeadFrame and MLF are trademarks of Amkor Technology.
MIC5252-x.xBML
1
EN 6CBYP
(optional)
VIN VOUT
COUT
5
4
2
3
ENABLE
SHUTDOWN
Ultra-Low-Noise Regulator Application
MIC5252 Micrel, Inc.
M9999-020305 2 February 2005
Pin Configuration
IN
OUTBYP
EN
L6xx
13
4 5
2
GND
MIC5252-x.xBM5
SOT-23-5 (M5)
(Top View)
1EN
GND
IN
6 BYP
NC
OUT
5
4
2
3
MIC5252-x.xBML
6-Pin 2mm × 2mm MLF™ (ML)
(Top View)
Pin Description
Pin Number Pin Number Pin Name Pin Function
SOT-23-5 6-MLF™
1 3 IN Supply Input.
2 2 GND Ground.
3 1 EN Enable/Shutdown (Input): CMOS compatible input. Logic high = enable;
logic low = shutdown. Do not leave open.
4 6 BYP Reference Bypass: Connect external 0.01µF ≤ CBYP ≤ 1.0µF capacitor to
GND to reduce output noise. May be left open.
5 4 OUT Regulator Output.
– 5 NC No internal connection.
– EP GND Ground: Internally connected to the exposed pad. Connect externally to
GND pin.
Ordering Information
Part Number Marking
Voltage
Junction Temp. Range
Package
Standard Pb-Free Standard Pb-Free
MIC5252-1.8BM5 MIC5252-1.8YM5 L618 L618 1.8V -40°C to +125°C SOT-23-5
MIC5252-2.5BM5 MIC5252-2.5YM5 L625 L625 2.5V -40°C to +125°C SOT-23-5
MIC5252-2.8BM5 MIC5252-2.8YM5 L628 L628 2.8V -40°C to +125°C SOT-23-5
MIC5252-2.85BM5 MIC5252-2.85YM5 L62J L62J 2.85V -40°C to +125°C SOT-23-5
MIC5252-3.0BM5 MIC5252-3.0YM5 L630 L630 3.0V -40°C to +125°C SOT-23-5
MIC5252-4.75BM5 MIC5252-4.75YM5 L64H L64H 4.75V -40°C to +125°C SOT-23-5
MIC5252-2.8BML MIC5252-2.8YML 628 628 2.8V -40°C to +125°C 6-Pin 2x2 MLF™
MIC5252-2.85BML MIC5252-2.85YML 62J 62J 2.85V -40°C to +125°C 6-Pin 2x2 MLF™
MIC5252-3.0BML MIC5252-3.0YML 630 630 3.0V -40°C to +125°C 6-Pin 2x2 MLF™
Other voltages available. Contact Micrel for details.
MIC5252 Micrel, Inc.
February 2005 3 M9999-020305
Electrical Characteristics(5)
VIN = VOUT + 1V, VEN = VIN; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.
Symbol Parameter Conditions Min Typical Max Units
VO Output Voltage Accuracy IOUT = 100µA –1 1 %
–3 3 %
ΔVLNR Line Regulation VIN = VOUT + 1V to 6V 0.02 0.2 %
ΔVLDR Load Regulation IOUT = 0.1mA to 150mA(6) 0.6 1.5 %
VIN – VOUT Dropout Voltage(7) IOUT = 100µA 0.1 5 mV
IOUT = 100mA 90 150 mV
IOUT = 150mA 135 200 mV
250 mV
IQ Quiescent Current VEN ≤ 0.4V (shutdown) 0.2 1 µA
IGND Ground Pin Current(8) IOUT = 0mA 90 150 µA
IOUT = 150mA 117 200 µA
PSRR Ripple Rejection; IOUT = 150mA f = 10Hz, COUT = 1.0µF, CBYP = 0.01µF 63 dB
f = 10Hz, VIN = VOUT + 0.3V 48 dB
f = 10kHz, VIN = VOUT + 0.3V 48 dB
ILIM Current Limit VOUT = 0V 250 425 mA
en Output Voltage Noise COUT = 1.0µF, CBYP = 0.01µF, 30
µV(rms)
f = 10Hz to 100kHz
Enable Input
VIL Enable Input Logic-Low Voltage VIN = 2.7V to 5.5V, regulator shutdown 0.4 V
VIH Enable Input Logic-High Voltage VIN = 2.7V to 5.5V, regulator enabled 1.6 V
IEN Enable Input Current VIL ≤ 0.4V, regulator shutdown 0.01 1 µA
VIH ≥ 1.6V, regulator enabled 0.01 1 µA
Shutdown Resistance Discharge 500 Ω
Thermal Protection
Thermal Shutdown Temperature 150 °C
Thermal Shutdown Hysteresis 10 °C
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function outside its operating rating.
3. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = (TJ(max)–TA)/θJA. Exceeding the maximum allowable
power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The θJA of the MIC5252-x.xBM5 (all ver-
sions) is 235°C/W on a PC board. See ”Thermal Considerations” section for further details.
4. Devices are ESD sensitive. Handling precautions recommended.
5. Specification for packaged product only.
6. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range
from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
7. Dropout Voltage is defined as the input-to-output differential at which the output voltage drops 2% below its nominal value measured at 1V differen-
tial. For outputs below 2.7V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7V. Minimum input operating
voltage is 2.7V.
8. Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus the ground pin cur-
rent.
Absolute Maximum Ratings(1)
Supply Input Voltage (VIN) ....................................0V to +7V
Enable Input Voltage (VEN) ..................................0V to +7V
Power Dissipation (PD) ..........................Internally Limited(3)
Junction Temperature (TJ) ........................ –40°C to +125°C
Storage Temperature ................................ –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ........................ 260°C
ESD(4) ............................................................................ 2kV
Operating Ratings(2)
Input Voltage (VIN) .......................................... +2.7V to +6V
Enable Input Voltage (VEN) ...................................0V to VIN
Junction Temperature (TJ) ........................ –40°C to +125°C
Thermal Resistance
SOT-23 (θJA) ......................................................235°C/W
2x2 MLF™ (θJA) ..................................................90°C/W
MIC5252 Micrel, Inc.
M9999-020305 4 February 2005
Typical Characteristics
2.65
2.67
2.69
2.71
2.73
2.75
2.77
2.79
2.81
2.83
2.85
0 20 40 60 80 100 120 140
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
Output V oltage
vs . L oa d C urrent
2.8V OUT
2.7
2.72
2.74
2.76
2.78
2.8
2.82
2.84
-40 -20 0 20 40 60 80 100 120
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
Output V oltage
vs . Temperature
100µA
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140 160
GROUND CURRENT (µA)
OUTPUT CURRENT (mA)
G round C urrent
vs . Output C urrent
2.8V OUT
0
20
40
60
80
100
120
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
GROUND CURRENT (µA)
SUPPLY VOLTAGE (V)
G round C urrent
vs . S uppl
y
Voltage
1µA Load
100µA Load
0µA Load
0
20
40
60
80
100
120
140
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
GROUND CURRENT (µA)
SUPPLY VOLTAGE (V)
G round C urrent
vs . S uppl
y
Voltage
10mA Load
150mA Load
0
0.5
1
1.5
2
2.5
3
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
OUTPUT VOLTAGE (V)
SUPPLY VOLTAGE (V)
Dropout C harac teris tic s
150mA
100
µ
A
0
20
40
60
80
100
120
140
160
180
200
-40 -20 0 20 40 60 80 100 120
DROPOUT VOLTAGE (mV)
TEMPERATURE (°C)
Dropout
vs . Temperature
2.8V OUT
IL= 150mA
0
20
40
60
80
100
120
140
160
-40 -20 0 20 40 60 80 100 120
GROUND CURRENT (µA)
TEMPERATURE (°C)
G round C urrent
vs . Temperature
0mA Load
150mA Load
100
10
0
10
20
30
40
50
60
70
80
90
PSRR (dB)
FREQUENCY (Hz)
P S R R with B ypas s V ariation
(V IN = V OUT + 0.3V)
1µF
100nF
10nF 0nF
COUT = 1µF C era mic
VIN = V O U T + 0.3V
VOUT = 2.8V
Load = 150mA
1k 10k 100k 1M
100
10
10
20
30
40
50
60
70
80
90
PSRR (dB)
FREQUENCY (Hz)
P S R R with L oad Varia tion
150mA
100µA
COUT = 1µF C era mic
CB Y P = 10nF
VIN = V O U T + 1V
VOUT = 2.8V
1k 10k 100k 1M
0
10
20
30
40
50
60
70
80
90
0
100
200
300
400
500
600
700
800
900
1000
PSRR (dB)
VOLTAGE DROP (mV)
P S R R
at 100Hz
100µA
COUT = 1µF
CB Y P = 10nF
VOUT 2.8V
150mA
100
10
0
10
20
30
40
50
60
70
80
90
PSRR (dB)
FREQUENCY (Hz)
P S R R with B ypas s C ap
Variation (V IN = VO UT + 1V )
1µF
100nF
10nF
0nF
COUT = 1µF C eramic
VIN = V O U T + 1V
VOUT = 2.8V
Load = 150mA
1k 10k 100k 1M
MIC5252 Micrel, Inc.
February 2005 5 M9999-020305
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
2.7 3.2 3.7 4.2 4.7 5.2 5.7 6.2
ENABLE THRESHOLD (V)
SUPPLY VOLTAGE (V)
E nable Thres hold
vs . S uppl
y
Voltage
E nable Off
E nable On
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
-40 -20 0 20 40 60 80 100 120
ENABLE THRESHOLD (V)
TEMPERATURE (°C)
E nable T hres hold
vs . Temperature
VIN = 5V
VIN = 3.8V
0
50
100
150
200
250
300
350
400
450
500
2.7 3.2 3.7 4.2 4.7 5.2
SHORT CIRCUIT CURRENT (mA)
SUPPLY VOLTAGE (V)
S hort C ircuit C urrent
vs . Input S uppl
y
Voltage
2.8V OUT
MIC5252 Micrel, Inc.
M9999-020305 6 February 2005
EnablePin Delay
TIME (10µs/div)
OutputVoltage
(1V/div)
EnableVoltage
(1V/div)
VOUT = 2.85V
VIN = 3.6V
COUT = 1µF Ceramic
100µA
150mA
Load Transient Response
TIME (40µs/div)
OutputCurrent
(100mA/div)
OutputVoltage
(50mV/div)
50mALoad
Line Transient Response
TIME (10µs/div)
OutputVoltage
(200mV/div)
InputVoltage
(1V/div)
3.3V
5V
Functional Characteristics
MIC5252 Micrel, Inc.
February 2005 7 M9999-020305
Block Diagram
Reference
Voltage
Startup/
Shutdown
Control
E N
Quickstart/
Noise
Cancellation
Under-
voltage
Lockout
Thermal
Sensor
IN
FAULT
Error
Amplifier
Current
Amplifier
GND
B Y P
OU T
ACT IV E SH U TDOWN
MIC5252 Micrel, Inc.
M9999-020305 8 February 2005
Applications Information
Enable/Shutdown
The MIC5252 comes with an active-high enable pin that al-
lows the regulator to be disabled. Forcing the enable pin low
disables the regulator and sends it into a “zero” off-mode-cur-
rent state. In this state, current consumed by the regulator
goes nearly to zero. Forcing the enable pin high enables
the output voltage. This part is CMOS and the enable pin
cannot be left floating; a floating enable pin may cause an
indeterminate state on the output.
Input Capacitor
The MIC5252 is a high performance, high bandwidth device.
Therefore, it requires a well-bypassed input supply for opti-
mal performance. A 1µF capacitor is required from the input
to ground to provide stability. Low-ESR ceramic capacitors
provide optimal performance at a minimum of space. Addi-
tional high-frequency capacitors, such as small valued NPO
dielectric type capacitors, help filter out high frequency noise
and are good practice in any RF based circuit.
Output Capacitor
The MIC5252 requires an output capacitor for stability. The
design requires 1µF or greater on the output to maintain stabil-
ity. The design is optimized for use with low-ESR ceramic chip
capacitors. High ESR capacitors may cause high frequency
oscillation. The maximum recommended ESR is 300mΩ.
The output capacitor can be increased, but performance has
been optimized for a 1µF ceramic output capacitor and does
not improve significantly with larger capacitance.
X7R/X5R dielectric-type ceramic capacitors are recom-
mended 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 operat-
ing 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.
Bypass Capacitor
A capacitor is required from the noise bypass pin to ground
to reduce output voltage noise. The capacitor bypasses
the internal reference. A 0.01µF capacitor is recommended
for applications that require low-noise outputs. The bypass
capacitor can be increased, further reducing noise and im-
proving PSRR. Turn-on time increases slightly with respect
to bypass capacitance. A unique quick-start circuit allows
the MIC5252 to drive a large capacitor on the bypass pin
without significantly slowing turn-on time. Refer to the “Typi-
cal Characteristics” section for performance with different
bypass capacitors.
Active Shutdown
The MIC5252 also features an active shutdown clamp, which
is an N-Channel MOSFET that turns on when the device is
disabled. This allows the output capacitor and load to dis-
charge, de-energizing the load.
No-Load Stability
The MIC5252 will remain stable and in regulation with no
load unlike many other voltage regulators. This is especially
important in CMOS RAM keep-alive applications.
Thermal Considerations
The MIC5252 is designed to provide 150mA of continuous
current in a very small package. Maximum power dissipation
can be calculated based on the output current and the voltage
drop across the part. To determine the maximum power dis-
sipation of the package, use the junction-to-ambient thermal
resistance of the device and the following basic equation:
P (max) T (max) T
DJ A
JA
=−
θ
TJ(max) is the maximum junction temperature of the die,
125°C, and TA is the ambient operating temperature. θJA is
layout dependent; Table 1 shows examples of junction-to-
ambient thermal resistance for the MIC5252.
Package θJA Recommended θJA 1” Square θJC
Minimum Footprint Copper Clad
SOT-23-5 235°C/W 185°C/W 145°C/W
(M5 or D5)
Table 1. SOT-23-5 Thermal Resistance
The actual power dissipation of the regulator circuit can be
determined using the equation:
PD = (VIN – VOUT) IOUT + VIN IGND
Substituting PD(max) for PD and solving for the operating
conditions that are critical to the application will give the
maximum operating conditions for the regulator circuit. For
example, when operating the MIC5252-2.8BM5 at 50°C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:
P (max) 125 C 50 C
235 C/W
D=° − °
°
PD(max) = 315mW
The junction-to-ambient thermal resistance for the minimum
footprint is 235°C/W, from Table 1. The maximum power dis-
sipation must not be exceeded for proper operation. Using
the output voltage of 2.8V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 100µA over
the load range, the power dissipation contributed by the ground
current is < 1% and can be ignored for this calculation.
315mW = (VIN – 2.8V) 150mA
315mW = VIN × 150mA – 420mW
735mW = VIN × 150mA
VIN(max) = 4.9V
Therefore, a 2.8V application at 150mA of output current
can accept a maximum input voltage of 4.9V in a SOT-23-5
package. For a full discussion of heat sinking and thermal
effects on voltage regulators, refer to the “Regulator Ther-
mals” section of Micrel’s Designing with Low-Dropout Voltage
Regulators handbook.
MIC5252 Micrel, Inc.
February 2005 9 M9999-020305
Package Information
SOT-23-5 (M5)
6-Pin MLF™ (ML)
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
This 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