MIC5205

Micrel

November 2002

MIC5205

General Description

The MIC5205 is an efficient linear voltage regulator with ultra-
low-noise output, very low dropout voltage (typically 17mV at
light loads and 165mV at 150mA), and very low ground
current (600

A at 100mA output). The MIC5205 offers better

than 1% initial accuracy.

Designed especially for hand-held, battery-powered devices,
the MIC5205 includes a CMOS or TTL compatible enable/
shutdown control input. When shutdown, power consump-
tion drops nearly to zero. Regulator ground current increases
only slightly in dropout, further prolonging battery life.

Key MIC5205 features include a reference bypass pin to
improve its already excellent low-noise performance, re-
versed-battery protection, current limiting, and
overtemperature shutdown.

The MIC5205 is available in fixed and adjustable output
voltage versions in a small SOT-23-5 package.

For low-dropout regulators that are stable with ceramic
output capacitors, see the

Cap MIC5245/6/7 family.

Typical Application

OUT

= 2.2µF

tantalum

BYP

Enable

Shutdown

OUT

Low-Noise Operation:
C

BYP

= 470pF, C

OUT

2.2µF

Basic Operation:
C

BYP

= not used, C

OUT

1µF

MIC5205-x.xBM5

EN (pin 3) may be
connected directly
to IN (pin 1).

Ultra-Low-Noise Regulator Application

MIC5205

150mA Low-Noise LDO Regulator

Final Information

Features

· Ultra-low-noise output
· High output voltage accuracy
· Guaranteed 150mA output
· Low quiescent current
· Low dropout voltage
· Extremely tight load and line regulation
· Very low temperature coefficient
· Current and thermal limiting
· Reverse-battery protection
· "Zero" off-mode current
· Logic-controlled electronic enable

Applications

· Cellular telephones
· Laptop, notebook, and palmtop computers
· Battery-powered equipment
· PCMCIA V

and V

regulation/switching

· Consumer/personal electronics
· SMPS post-regulator/dc-to-dc modules
· High-efficiency linear power supplies

Micrel, Inc. · 1849 Fortune Drive · San Jose, CA 95131 · USA · tel + 1 (408) 944-0800 · fax + 1 (408) 944-0970 · http://www.micrel.com

MIC5205

Micrel

MIC5205

November 2002

Pin Configuration

OUT

BYP

LBxx or

KBxx

Part
Identification

OUT

ADJ

LBAA

GND

MIC5205-x.xBM5

MIC5205BM5

Fixed Voltages

Adjustable Voltage

Absolute Maximum Ratings

(Note 1)

Supply Input Voltage (V

) ............................ 20V to +20V

Enable Input Voltage (V

) ........................... 20V to +20V

Power Dissipation (P

) ............... Internally Limited, Note 3

Lead Temperature (soldering, 5 sec.) ....................... 260

Junction Temperature (T

) ....................... 40

C to +125

Storage Temperature (T

) ....................... 65

C to +150

Operating Ratings

(Note 2)

Input Voltage (V

) ....................................... +2.5V to +16V

Enable Input Voltage (V

) .................................. 0V to V

Junction Temperature (T

) ....................... 40

C to +125

Thermal Resistance, SOT-23-5

(

) ....................... Note 3

Pin Description

MIC5205-x.x

MIC5205

Pin Name

Pin Function

(fixed)

(adjustable)

Supply Input

GND

Ground

Enable/Shutdown (Input): CMOS compatible input. Logic high = enable,
logic low or open = shutdown.

BYP

Reference Bypass: Connect external 470pF capacitor to GND to reduce
output noise. May be left open.

ADJ

Adjust (Input): Adjustable regulator feedback input. Connect to resistor
voltage divider.

OUT

Regulator Output

Ordering Information

Part Number

Marking

Voltage

Accuracy

Junction Temp. Range*

Package

MIC5205BM5

LBAA

Adj

C to +125

SOT-23-5

MIC5205-2.5BM5

LB25

2.5V

C to +125

SOT-23-5

MIC5205-2.7BM5

LB27

2.7V

C to +125

SOT-23-5

MIC5205-2.8BM5

LB28

2.8V

C to +125

SOT-23-5

MIC5205-2.85BM5

LB2J

2.85V

C to +125

SOT-23-5

MIC5205-2.9BM5

LB29

2.9V

C to +125

SOT-23-5

MIC5205-3.0BM5

LB30

3.0V

C to +125

SOT-23-5

MIC5205-3.1BM5

LB31

3.1V

C to +125

SOT-23-5

MIC5205-3.2BM5

LB32

3.2V

C to +125

SOT-23-5

MIC5205-3.3BM5

LB33

3.3V

C to +125

SOT-23-5

MIC5205-3.6BM5

LB36

3.6V

C to +125

SOT-23-5

MIC5205-3.8BM5

LB38

3.8V

C to +125

SOT-23-5

MIC5205-4.0BM5

LB40

4.0V

C to +125

SOT-23-5

MIC5205-5.0BM5

LB50

5.0V

C to +125

SOT-23-5

MIC5205-2.5YM5

KB25

2.5V

C to +125

C (lead free)

SOT-23-5

*Other voltages available. Contact Micrel for details.

MIC5205

Micrel

November 2002

MIC5205

Electrical Characteristics

= V

OUT

+ 1V; I

= 100

A; C

= 1.0

F; V

2.0V; T

= 25

C, bold values indicate 40

+125

C; unless noted.

Symbol

Parameter

Conditions

Min

Typical

Max

Units

Output Voltage Accuracy

variation from specified V

OUT

Output Voltage

Note 4

ppm/

Temperature Coefficient

Line Regulation

= V

OUT

+ 1V to 16V

0.004

0.012

% / V

0.05

% / V

Load Regulation

= 0.1mA to 150mA, Note 5

0.02

0.2

0.5

Dropout Voltage, Note 6

= 100

= 50mA

110

150

230

= 100mA

140

250

300

= 150mA

165

275

350

GND

Quiescent Current

0.4V (shutdown)

0.01

0.18V (shutdown)

GND

Ground Pin Current, Note 7

2.0V, I

= 100

125

150

= 50mA

350

600

800

= 100mA

600

1000

1500

= 150mA

1300

1900

2500

PSRR

Ripple Rejection

frequency = 100Hz, I

= 100

LIMIT

Current Limit

OUT

= 0V

320

500

Thermal Regulation

Note 8

0.05

%/W

Output Noise

= 50mA, C

= 2.2

260

nV/ Hz

470pF from BYP to GND

ENABLE Input

Enable Input Logic-Low Voltage

regulator shutdown

0.4

0.18

Enable Input Logic-High Voltage

regulator enabled

2.0

Enable Input Current

0.4V

0.01

0.18V

2.0V

Note 1.

Exceeding the absolute maximum rating may damage the device.

Note 2.

The device is not guaranteed to function outside its operating rating.

Note 3:

The maximum allowable power dissipation at any T

(ambient temperature) is P

D(max)

= (T

J(max)

)

. Exceeding the maximum

allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The

of the MIC5205-

xxBM5 (all versions) is 220

C/W mounted on a PC board (see "Thermal Considerations" section for further details).

Note 4:

Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.

Note 5:

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.

Note 6:

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.

Note 7:

Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of
the load current plus the ground pin current.

Note 8:

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 150mA load pulse at V

= 16V for t = 10ms.

MIC5205

Micrel

MIC5205

November 2002

Typical Characteristics

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100

OUT

= 1

= 6V

OUT

= 5V

100

10k 100k 1M 10M

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100

OUT

= 2.2

BYP

= 0.01

= 6V

OUT

= 5V

100

10k 100k 1M 10M

0.1

0.2

0.3

0.4

RIPPLE REJECTION (dB)

VOLTAGE DROP (V)

Power Supply Ripple Rejection

vs. Voltage Drop

OUT

= 100mA

10mA

1mA

OUT

= 1

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 1mA

OUT

= 1

= 6V

OUT

= 5V

100

10k 100k 1M 10M

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 1mA

OUT

= 2.2

BYP

= 0.01

= 6V

OUT

= 5V

100

10k 100k 1M 10M

100

0.1

0.2

0.3

0.4

RIPPLE REJECTION (dB)

VOLTAGE DROP (V)

Power Supply Ripple Rejection

vs. Voltage Drop

OUT

= 100mA

10mA

1mA

OUT

= 2.2

BYP

= 0.01

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 10mA

OUT

= 1

= 6V

OUT

= 5V

100

10k 100k 1M 10M

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 10mA

OUT

= 2.2

BYP

= 0.01

= 6V

OUT

= 5V

100

10k 100k 1M 10M

100

1000

10000

100

1000

10000

TIME (

CAPACITANCE (pF)

Turn-On Time

vs. Bypass Capacitance

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100mA

OUT

= 1

= 6V

OUT

= 5V

100

10k 100k 1M 10M

-100

-80

-60

-40

-20

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100mA

OUT

= 2.2

BYP

= 0.01

= 6V

OUT

= 5V

100

10k 100k 1M 10M

120

160

200

240

280

320

120

160

DROPOUT VOLTAGE (mV)

OUTPUT CURRENT (mA)

Dropout Voltage

vs. Output Current

+125

+25

MIC5205

Micrel

November 2002

MIC5205

Typical Characteristics

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

100

10k 100k 1M 10M

1mA

OUT

= 1

BYP

= 10nF

10mA, C

OUT

= 1

OUT

= 5V

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

10mA

1mA

100mA

100

10k 100k 1M 10M

OUT

= 5V

OUT

= 10

electrolytic

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

10mA

1mA

100mA

100

10k 100k 1M 10M

OUT

= 5V

OUT

= 22

tantalum
C

BYP

= 10nF

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

10mA

1mA

100mA

100

10k 100k 1M 10M

OUT

= 5V

OUT

= 10

electrolytic
C

BYP

= 100pF

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

10mA

1mA

100mA

100

10k 100k 1M 10M

OUT

= 5V

OUT

= 10

electrolytic
C

BYP

= 1nF

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6 1E+7

NOISE (

Hz)

FREQUENCY (Hz)

Noise Performance

10mA

1mA

100mA

100

10k 100k 1M 10M

OUT

= 5V

OUT

= 10

electrolytic
C

BYP

= 10nF

MIC5205

Micrel

November 2002

MIC5205

Applications Information

Enable/Shutdown

Forcing EN (enable/shutdown) high (> 2V) enables the regu-
lator. EN is compatible with CMOS logic gates.

If the enable/shutdown feature is not required, connect EN
(pin 3) to IN (supply input, pin 1). See Figure 1.

Input Capacitor

A 1

F capacitor should be placed from IN to GND if there is

more than 10 inches of wire between the input and the ac filter
capacitor or if a battery is used as the input.

Reference Bypass Capacitor

BYP (reference bypass) is connected to the internal voltage
reference. A 470pF capacitor (C

BYP

) connected from BYP to

GND quiets this reference, providing a significant reduction in
output noise. C

BYP

reduces the regulator phase margin;

when using C

BYP

, output capacitors of 2.2

F or greater are

generally required to maintain stability.

The start-up speed of the MIC5205 is inversely proportional
to the size of the reference bypass capacitor. Applications
requiring a slow ramp-up of output voltage should consider
larger values of C

BYP

. Likewise, if rapid turn-on is necessary,

consider omitting C

BYP

If output noise is not a major concern, omit C

BYP

and leave

BYP open.

Output Capacitor

An output capacitor is required between OUT and GND to
prevent oscillation. The minimum size of the output capacitor
is dependent upon whether a reference bypass capacitor is
used. 1.0

F minimum is recommended when C

BYP

is not

used (see Figure 2). 2.2

F minimum is recommended when

BYP

is 470pF (see Figure 1). Larger values improve the

regulator's transient response. The output capacitor value
may be increased without limit.

The output capacitor should have an ESR (effective series
resistance) of about 5

or less and a resonant frequency

above 1MHz. Ultra-low-ESR capacitors can cause a low
amplitude oscillation on the output and/or underdamped
transient response. Most tantalum or aluminum electrolytic
capacitors are adequate; film types will work, but are more
expensive. Since many aluminum electrolytics have electro-
lytes that freeze at about 30

C, solid tantalums are recom-

mended for operation below 25

At lower values of output current, less output capacitance is
required for output stability. The capacitor can be reduced to
0.47

F for current below 10mA or 0.33

F for currents below

1mA.

No-Load Stability

The MIC5205 will remain stable and in regulation with no load
(other than the internal voltage divider) unlike many other
voltage regulators. This is especially important in CMOS
RAM keep-alive applications.

Thermal Considerations

The MIC5205 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
dissipation of the package, use the junction-to-ambient ther-
mal resistance of the device and the following basic equation:

D(max)

J(max)

(

)

J(max)

is the maximum junction temperature of the die,

125

C, and T

is the ambient operating temperature.

layout dependent; Table 1 shows examples of junction-to-
ambient thermal resistance for the MIC5205.

Package

Recommended

1" Square

Minimum Footprint

Copper Clad

SOT-23-5 (M5)

220

C/W

170

C/W

130

C/W

Table 1. SOT-23-5 Thermal Resistance

The actual power dissipation of the regulator circuit can be
determined using the equation:

= (V

OUT

) I

OUT

+ V

GND

Substituting P

D(max)

for P

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 MIC5205-3.3BM5 at room
temperature with a minimum footprint layout, the maximum
input voltage for a set output current can be determined as
follows:

125 C 25 C

C/W

D(max)

(

)

220

D(max)

= 455mW

The junction-to-ambient thermal resistance for the minimum
footprint is 220

C/W, from Table 1. The maximum power

dissipation must not be exceeded for proper operation. Using
the output voltage of 3.3V and an output current of 150mA,
the maximum input voltage can be determined. From the
Electrical Characteristics table, the maximum ground current
for 150mA output current is 2500

A or 2.5mA.

455mW = (V

3.3V) 150mA + V

·2.5mA

455mW = V

·150mA 495mW + V

·2.5mA

950mW = V

·152.5mA

IN(max)

= 6.23V

Therefore, a 3.3V application at 150mA of output current can
accept a maximum input voltage of 6.2V in a SOT-23-5
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 Regu-

lators handbook.

MIC5205

Micrel

MIC5205

November 2002

Fixed Regulator Applications

2.2µF

470pF

OUT

MIC5205-x.xBM5

Figure 1. Ultra-Low-Noise Fixed Voltage Application

Figure 1 includes a 470pF capacitor for low-noise operation
and shows EN (pin 3) connected to IN (pin 1) for an applica-
tion where enable/shutdown is not required. C

OUT

= 2.2

minimum.

1.0µF

Enable

Shutdown

OUT

MIC5205-x.xBM5

Figure 2. Low-Noise Fixed Voltage Application

Figure 2 is an example of a low-noise configuration where
C

BYP

is not required. C

OUT

= 1

F minimum.

Adjustable Regulator Applications

The MIC5205BM5 can be adjusted to a specific output
voltage by using two external resistors (Figure 3). The resis-
tors set the output voltage based on the following equation:

= 1.242V

+ 1

OUT

This equation is correct due to the configuration of the
bandgap reference. The bandgap voltage is relative to the
output, as seen in the block diagram. Traditional regulators
normally have the reference voltage relative to ground and
have a different V

OUT

equation.

Resistor values are not critical because ADJ (adjust) has a
high input impedance, but for best results use resistors of
470k

or less. A capacitor from ADJ to ground provides

greatly improved noise performance.

2.2µF

470pF

OUT

MIC5205BM5

Figure 3. Ultra-Low-Noise

Adjustable Voltage Application

Figure 3 includes the optional 470pF noise bypass capacitor
from ADJ to GND to reduce output noise.