MIC5259
300mA High PSRR, Low Noise µCap CMOS LDO
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
September 2006 1 M9999-091406
General Description
The MIC5259 is an efficient CMOS voltage regulator
optimized for low-noise applications. It offers 1.5% initial
accuracy, low dropout voltage (300mV at 300mA) and low
ground current (typically 105µA at light load). The
MIC5259 provides a very-low-noise output, ideal for RF
applications where a clean voltage source is required. The
MIC5259 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 MIC5259 provides a TTL-logic-compatible
enable pin. When disabled, power consumption drops to
nearly zero.
The MIC5259 also works with low-ESR ceramic
capacitors, reducing the amount of board space necessary
for power applications; critical issue 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 MIC5259 is available in the 6-pin
2mm × 2mm MLF
®
package and the 5-pin Thin SOT-23
package in a wide range of output voltages.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Input voltage range: 2.7V to 6.0V
• PSRR = 70dB @ 1kHz
• Low output noise: 30µV(rms)
• Stability with ceramic output capacitors
• Low-dropout: 300mV @ 300mA
• High-output accuracy:
– 1.5% initial accuracy
– 3.0% over temperature
• Low quiescent current: 105µA
• 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
• Industrial portable electronics
• PC peripherals
Typical Application
MIC5259-x.xBML/YML
1
EN
6
C
BYP
(optional)
V
IN
V
OUT
C
OUT
= 1.0µF
5
4
2
3
ENABLE
SHUTDOWN
C
IN
= 1.0µF 0.01µF
C
OUT
= 1.0µF
Ceramic
C
IN
= 1.0µF
Ceramic
15
2
34
C
BYP
= 0.01µF
Enable
Shutdown
EN
V
OUT
MIC5259-x.xBD5/YD5
EN (pin 3) may be
connected directly
to IN (pin 1).
V
IN
Ultra-Low Noise Regulator Application
Micrel, Inc. MIC5259
September 2006 2 M9999-091406
Ordering Information(1)
Part Number Marking
Standard Pb-Free Standard Pb-Free*
Voltage
Junction
Temp. Range** Package
MIC5259-1.5BD5 MIC5259-1.5YD5 NY15 NY15 1.5V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-1.8BD5 MIC5259-1.8YD5 NY18 NY18 1.8V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-2.5BD5 MIC5259-2.5YD5 NY25 NY25 2.5V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-2.8BD5 MIC5259-2.8YD5 NY28 NY28 2.8V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-2.85BD5 MIC5259-2.85YD5 NY2J NY2J 2.85V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-3.0BD5 MIC5259-3.0YD5 NY30 NY30 3.0V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-3.3BD5 MIC5259-3.3YD5 NY33 NY33 3.3V –40°C to +125°C 5-Pin Thin SOT23-5
MIC5259-1.5YML Y15 1.5V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-1.8YML Y18 1.8V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-2.1YML Y21 2.1V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-2.5BML MIC5259-2.5YML Y25 Y25 2.5V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-2.8BML MIC5259-2.8YML Y28 Y28 2.8V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-2.85BML MIC5259-2.85YML Y2J Y2J 2.85V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-3.0BML MIC5259-3.0YML Y30 Y30 3.0V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
MIC5259-3.3BML MIC5259-3.3YML Y33 Y33 3.3V –40°C to +125°C 6-Pin 2mm x 2mm MLF
®
* Under bar / Over bar symbol ( _ / ) may not be to scale.
** Other voltages available, please contact Micrel Marketing for details.
Pin Configuration
IN
OUTBYP
EN
NYxx
13
45
2
GND
NYxx
1EN
GND
IN
6 BYP
NC
OUT
5
4
2
3
Yxx
Yxx
MIC5259-x.xBD5/YD5
5-Pin Thin SOT-23 (D5)
(Top View)
MIC5259-x.xBML/YML
6-Pin 2mm x 2mm MLF
®
(ML)
(Top View)
Pin Description
Pin Number
TSOT-23-5
Pin Number
MLF
®
-6
Pin Name Pin Name
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 Connect
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September 2006 3 M9999-091406
Absolute Maximum Ratings(1)
Supply Input Voltage (V
IN
).................................... 0V to +7V
Enable Input Voltage (V
EN
)................................... 0V to +7V
Power Dissipation (P
D
) ........................... Internally Limited
(3)
Junction Temperature (T
J
) ........................–40°C to +125°C
Storage Temperature (T
S
)........................... –65°C to 150°C
Lead Temperature (soldering, 5sec.)......................... 260°C
EDS Rating
(4)
.................................................................. 2kV
Operating Ratings(2)
Supply voltage (V
IN
) ........................................ +2.7V to +6V
Enable Input Voltage (V
EN
)..................................... 0V to V
IN
Junction Temperature (T
J
) ........................ –40°C to +125°C
Thermal Resistance
TSOT-23 (θ
JA
)..................................................235°C/W
2x2 MLF
®
(θ
JA
)...................................................90°C/W
Electrical Characteristics(5)
V
IN
= V
OUT
+ 1V; V
EN
= V
IN;
I
OUT
= 100µA; T
J
= 25°C, bold values indicate –40°C< T
J
< +125°C, unless noted.
Symbol Parameter Condition Min Typ Max Units
V
O
Output Voltage Accuracy I
OUT
= 100µA –1.5
–3
1.5
3
%
%
V
LRN
Line Regulation V
IN
= V
OUT
+ 1V to 6V –0.3 0.02 0.3 %/V
V
LDR
Load Regulation I
OUT
= 0.1mA to 300mA(6) 0.6 3.0 %
I
OUT
= 150mA 150 mV V
IN
– V
OUT
Dropout Voltage
(7)
I
OUT
= 300mA 300 500
550
mV
mV
I
Q
Quiescent Current V
EN
0.4V (shutdown) 0.2 1 µA
I
OUT
= 0mA 105 150 µA I
GND
Ground Pin Current
(8)
I
OUT
= 300mA 120 250 µA
f = 10Hz, C
OUT
= 1.0µF, C
BYP
= 0.01µF 65 dB
f = 10Hz, V
IN
= V
OUT
+ 0.3V 53 dB
PSRR Ripple Rejection; I
OUT
= 150mA
f = 10kHz, V
IN
= V
OUT
+ 0.3V 53 dB
I
LIM
Current Limit V
OUT
= 0V 350 475 mA
e
n
Output Voltage Noise C
OUT
1.0µF, C
BYP
= 0.01µF,
f = 10Hz to 100kHz
30 µV
(RMS)
Enable Input
V
IL
Enable Input Logic-Low Voltage V
IN
= 2.7 to 5.5V, regulator shutdown 0.4 V
V
IH
Enable Input Logic-High Voltage V
IN
= 2.7V to 5.5V, regulator enabled 1.6 V
V
IL
0.4V, regulator shutdown 0.01 1 µA I
EN
Enable Input Current
V
IH
1.6V, regulator enabled 0.01 1 µA
Shutdown Resistance Discharge 500
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 T
A
(ambient temperature) is P
D(max)
= (T
J(max)
– T
A
) /
JA
. Exceeding the maximum allowable power
dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The
JA
of the MIC5259-x.xBM5 (all versions) 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 300mA. 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 differential.
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
current.
Micrel, Inc. MIC5259
September 2006 4 M9999-091406
Typical Characteristics
Micrel, Inc. MIC5259
September 2006 5 M9999-091406
Typical Characteristics (cont.)
Micrel, Inc. MIC5259
September 2006 6 M9999-091406
Functional Characteristics
Micrel, Inc. MIC5259
September 2006 7 M9999-091406
Functional Diagram
Reference
Voltage
Startup/
Shutdown
Control
EN
Quickstart/
Noise
Cancellation
Under-
voltage
Lockout
Thermal
Sensor
IN
FAULT
Error
Amplifier Current
Amplifier
GND
BYP
OUT
ACTIVE SHUTDOWN
Micrel, Inc. MIC5259
September 2006 8 M9999-091406
Application Information
Enable/Shutdown
The MIC5259 comes with an active-high enable pin that
allows the regulator to be disabled. Forcing the enable
pin low disables the regulator and sends it into a “zero”
off-mode-current 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 MIC5259 is a high performance, high bandwidth
device. Therefore, it requires a well-bypassed input
supply for optimal performance. A 1µF capacitor is
required from the input-to-ground to provide stability.
Low-ESR ceramic capacitors provide optimal perform-
ance at a minimum of space. Additional 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 MIC5259 requires an output capacitor for stability.
The design requires 1µF or greater on the output to
maintain stability. 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 300m. 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
recommended because of their temperature perform-
ance. 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.
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 improving PSRR. Turn-on time
increases slightly with respect to bypass capacitance. A
unique quick-start circuit allows the MIC5259 to drive a
large capacitor on the bypass pin without significantly
slowing turn-on time. Refer to the “Typical Character-
istics” section for performance with different bypass
capacitors.
Active Shutdown
The MIC5259 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 discharge, de-energizing the load.
No-Load Stability
The MIC5259 will remain stable and in regulation with no
load unlike many other voltage regulators. This is
especially important in CMOS RAM keep-alive applica-
tions.
Thermal Considerations
The MIC5259 is designed to provide 300mA 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 dissipation of the
package, use the junction-to-ambient thermal resistance
of the device and the following basic equation:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛−
=
JA
AJ(max)
D(max)
TT
P
TJ(max) is the maximum junction temperature of the die,
125°C, and TA is the ambient operating temperature.
JA is layout dependent; Table 1 shows examples of
junction-to-ambient thermal resistance for the MIC5259.
Package θ
JA
Recommended
Minimum Footprint
θ
JA
1” Square
Copper Clad
θ
JC
SOT-23-5
(M5 or D5)
235°C/W 185°C/W 145°C/W
MLF (ML) 90°C/W
Table 1. Thermal Resistance
Micrel, Inc. MIC5259
September 2006 9 M9999-091406
The actual power dissipation of the regulator circuit can
be determined using the equation:
P
D
= (V
IN
– V
OUT
) I
OUT
+ V
IN
I
GND
Substituting P
D(max)
for P
D
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 MIC5259-2.8BML at
70°C with a minimum footprint layout, the maximum
input voltage for a set output current can be determined
as follows:
⎟
⎠
⎞
⎜
⎝
⎛
°
°−°
=C/W90
C70C125
P
D(max)
P
D(max)
= 611mW
The junction-to-ambient thermal resistance for the
minimum footprint is 90°C/W, from Table 1. The
maximum power dissipation must not be exceeded for
proper operation. Using the output voltage of 2.8V and
an output current of 200mA, the maximum input voltage
can be determined. Because this device is CMOS and
the ground current is typically 110µA over the load
range, the power dissipation contributed by the ground
current is < 1% and can be ignored for this calculation.
611mW = (V
IN
– 2.8V) 200mA
611mW = V
IN
× 200mA – 560mW
1171mW = V
IN
× 200mA
V
IN(max)
= 5.85V
Therefore, a 2.8V application at 200mA of output current
can accept a maximum input voltage of 5.85V in an MLF
package. For a full discussion of heat sinking and
thermal effects on voltage regulators, refer to the
“Regulator Thermals” section of Micrel’s Designing with
Low-Dropout Voltage Regulators handbook.
Micrel, Inc. MIC5259
September 2006 10 M9999-091406
Package Information
5-Pin Thin SOT-23 (D5)
6-Pin 2mm x 2mm MLF
®
(ML)
Micrel, Inc. MIC5259
September 2006 11 M9999-091406
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.
© 2004 Micrel, Incorporated.
