MIC5219_01_技术文档

MIC5219

Micrel

MIC5219

500mA-Peak Output LDO Regulator

General Description

Features

The MIC5219 is an efficient linear voltage regulator with high

peak output current capability, very low dropout voltage, and

better than 1% output voltage accuracy. Dropout is typically

10mV at light loads and less than 500mV at full load.

• 500mA Output current capability

• SOT-23-5 package - 500mA peak

• MSOP-8 package - 500mA continuous

• Low 500mV maximum dropout voltage at full load

• Extremely tight load and line regulation

• Tiny SOT-23-5 and MM8™ power MSOP-8 package

• Ultra-low-noise output

• Low temperature coefficient

• Current and thermal limiting

• Reversed-battery protection

• CMOS/TTL-compatible enable/shutdown control

• Near-zero shutdown current

TheMIC5219isdesignedtoprovideapeakoutputcurrentfor

startup conditions where higher inrush current is demanded.

It features a 500mA peak output rating. Continuous output

current is limited only by package and layout.

The MIC5219 can be enabled or shut down by a CMOS or

TTL compatible signal. When disabled, power consumption

drops nearly to zero. Dropout ground current is minimized to

helpprolongbatterylife.Otherkeyfeaturesincludereversed-

battery protection, current limiting, overtemperature shut-

down, and low noise performance with an ultra-low-noise

option.

Applications

• Laptop, notebook, and palmtop computers

• Cellular telephones and battery-powered equipment

• Consumer and personal electronics

The MIC5219 is available in adjustable or fixed output volt-

ages in space-saving SOT-23-5 and MM8™ 8-lead power

MSOP packages. For higher power requirements see the

MIC5209 or MIC5237.

• PC Card V and V regulation and switching

CC

PP

• SMPS post-regulator/dc-to-dc modules

• High-efficiency linear power supplies

Typical Applications

MIC5219-5.0BMM

1

2

3

4

8

7

6

5

ENABLE

SHUTDOWN

MIC5219-3.3BM5

1

2

3

5

V_IN6V

V_OUT5V

V_IN4V

V_OUT3.3V

2.2µF

tantalum

4

ENABLE

SHUTDOWN

2.2µF

tantalum

470pF

5V Ultra-Low-Noise Regulator

3.3V Ultra-Low-Noise Regulator

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

April 2001

1

MIC5219

Micrel

Ordering Information

Part Number

Marking

—

Volts

3.0V

3.3V

3.6V

5.0V

Adj.

Junction Temp. Range

–40°C to +125°C

Package

MSOP-8

SOT-23-5

MIC5219-3.0BMM

MIC5219-3.3BMM

MIC5219-3.6BMM

MIC5219-5.0BMM

MIC5219BMM

—

MIC5219-2.5BM5

MIC5219-2.6BM5

MIC5219-2.7BM5

MIC5219-2.8BM5

MIC5219-2.9BM5

MIC5219-3.0BM5

MIC5219-3.1BM5

MIC5219-3.3BM5

MIC5219-3.6BM5

MIC5219-5.0BM5

MIC5219BM5

LG25

LG26

LG27

LG28

LG29

LG30

LG31

LG33

LG36

LG50

LGAA

2.5V

2.6V

2.7V

2.8V

2.9V

3.0V

3.1V

3.3V

3.6V

5.0V

Adj.

Other voltages available. Consult Micrel for details.

Pin Configuration

EN GND IN

EN

IN

GND

1

2

3

4

8

7

6

5

3

2

1

LGxx

OUT

BYP

4

5

BYP

OUT

MIC5219-x.xBMM

MM8™ MSOP-8

Fixed Voltages

MIC5219-x.xBM5

SOT-23-5

Fixed Voltages

EN GND IN

EN

IN

GND

1

2

3

4

8

7

6

5

3

2

1

Part

Identification

LGAA

OUT

ADJ

4

5

ADJ

OUT

MIC5219BMM

MM8™ MSOP-8

Adjustable Voltage

MIC5219BM5

SOT-23-5

Adjustable Voltage

MIC5219

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April 2001

MIC5219

Micrel

Pin Description

Pin No.

Pin Name

Pin Function

MSOP-8

SOT-23-5

2

5–8

3

1

2

5

3

IN

Supply Input

GND

OUT

EN

Ground: MSOP-8 pins 5 through 8 are internally connected.

Regulator Output

1

Enable (Input): CMOS compatible control input. Logic high = enable; logic

low or open = shutdown.

4 (fixed)

4 (adj.)

4 (fixed)

4 (adj.)

BYP

ADJ

Reference Bypass: Connect external 470pF capacitor to GND to reduce

output noise. May be left open.

Adjust (Input): Feedback input. Connect to resistive voltage-divider network.

April 2001

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MIC5219

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Absolute Maximum Ratings

Operating Ratings

Supply Input Voltage (V ) ............................ –20V to +20V

Supply Input Voltage (V ) ........................... +2.5V to +12V

IN

Power Dissipation (P ) ............................ Internally Limited

Enable Input Voltage (V ) .................................. 0V to V

D

EN

IN

Junction Temperature (T ) ....................... –40°C to +125°C

J

Lead Temperature (Soldering, 5 sec.) ...................... 260°C

Package Thermal Resistance ......................... see Table 1

Electrical Characteristics

V_IN= V_OUT+ 1.0V; C_OUT= 4.7µF, I_OUT= 100µA; T_J= 25°C, bold values indicate –40°C ≤ T_J≤ +125°C; unless noted.

Symbol

Parameter

Conditions

Min Typical Max

Units

V_OUT

Output Voltage Accuracy

variation from nominal V_OUT

–1

–2

1

2

%

∆V_OUT/∆T

Output Voltage

Temperature Coefficient

Note 2

40

0.009

0.05

10

ppm/°C

%/V

%

∆V_OUT/V_OUTLine Regulation

V_IN= V_OUT+ 1V to 12V

I_OUT= 100µA to 500mA Note 3

I_OUT= 100µA

0.05

0.1

∆V_OUT/V_OUTLoad Regulation

0.5

0.7

V_IN– V_OUT

Dropout Voltage, Note 4

60

80

mV

µA

I_OUT= 50mA

115

175

350

80

175

250

I_OUT= 150mA

300

400

I

_OUT= 500mA

500

600

I_GND

Ground Pin Current, Notes 5, 6

V_EN≥ 3.0V, I_OUT= 100µA

V_EN≥ 3.0V, I_OUT= 50mA

V_EN≥ 3.0V, I_OUT= 150mA

V_EN≥ 3.0V, I_OUT= 500mA

130

170

350

1.8

650

900

µA

2.5

3.0

mA

12

20

25

Ground Pin Quiescent Current,

Note 6

V

_EN≤ 0.4V

0.05

0.10

75

3

8

µA

V_EN≤ 0.18V

PSRR

I_LIMIT

Ripple Rejection

Current Limit

f = 120Hz

dB

V_OUT= 0V

700

0.05

500

300

1000

mA

∆V_OUT/∆P_D

e_no

Thermal Regulation

Output Noise

Note 7

%/W

nV/ Hz

I_OUT= 50mA, C_OUT= 2.2µF, C_BYP= 0

I_OUT= 50mA, C_OUT= 2.2µF, C_BYP= 470pF

ENABLE Input

V_ENL

Enable Input Logic-Low Voltage

V_EN= logic low (regulator shutdown)

V_EN= logic high (regulator enabled)

0.4

0.18

V

2.0

2

V

I_ENL

Enable Input Current

V_ENL≤ 0.4V

V_ENL≤ 0.18V

V_ENH≥ 2.0V

0.01

5

–1

–2

µA

I_ENH

20

25

MIC5219

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April 2001

MIC5219

Micrel

Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when

operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction

temperature, T

, the junction-to-ambient thermal resistance, θ , and the ambient temperature, T . The maximum allowable power

J(max)

JA

A

dissipation at any ambient temperature is calculated using: P

= (T

– T ) ÷ θ . Exceeding the maximum allowable power dissipa-

D(max)

J(max)

A

JA

tion will result in excessive die temperature, and the regulator will go into thermal shutdown. See Table 1 and the “Thermal Considerations”

section for details.

Note 2: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.

Note 3: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load

range from 100µA to 500mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.

Note 4: 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 5: 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 6:

V

is the voltage externally applied to devices with the EN (enable) input pin.

EN

Note 7: 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 500mA load pulse at V = 12V for t = 10ms.

IN

Note 8:

C

is an optional, external bypass capacitor connected to devices with a BYP (bypass) or ADJ (adjust) pin.

BYP

April 2001

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MIC5219

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Typical Characteristics

Power Supply

Rejection Ratio

Power Supply

Rejection Ratio

Power Supply

Rejection Ratio

0

-20

0

-20

V_IN= 6V

V_OUT= 5V

V_IN= 6V

_OUT= 5V

V

_OUT= 5V

V

-20

-40

-60

I_OUT= 100mA

_OUT= 1µF

-80

I_OUT= 100µA

_OUT= 1µF

I_OUT= 1mA

_OUT= 1µF

C

-100

1E+11E+21E1+k311E0+k41E+51E1M+6 E+7

10 100 100k

10M

10 100

100k

10M

10 100

100k

10M

FREQUENCY (Hz)

Power Supply

Rejection Ratio

Power Supply

Rejection Ratio

Power Supply

Rejection Ratio

0

V_IN= 6V

_OUT= 5V

V_IN= 6V

_OUT= 5V

V_IN= 6V

V_OUT= 5V

V

-20

-40

-20

-40

-20

-40

-60

I_OUT= 1mA

I_OUT= 100µA

I_OUT= 100mA

C_OUT= 2.2µF

_BYP= 0.01µF

-80

C_OUT= 2.2µF

_BYP= 0.01µF

C_OUT= 2.2µF

_BYP= 0.01µF

C

-100

1E+11E+21E1+k311E0+k41E+51E1M+6 E+7

10 100 100k

10M

10 100

100k

10M

10 100

100k

10M

FREQUENCY (Hz)

Power Supply Ripple Rejection

vs. Voltage Drop

Power Supply Ripple Rejection

vs. Voltage Drop

Noise Performance

60

100

10

1

90

80

70

60

50

40

30

20

10

0

10mA, C_OUT= 1µF

50

40

30

20

10

0

1mA

0.1

I_OUT= 100mA

10mA

I_OUT= 100mA

0.01

0.001

0.0001

10mA

C_OUT= 2.2µF

C_BYP= 0.01µF

C_OUT= 1µF

V_OUT= 5V

0

0.1

0.2

0.3

0.4

0

0.1

0.2

0.3

0.4

1E+11E+21E+31E+41E+51E+61E+7

10

1k

100

10k 100k 1M 10M

VOLTAGE DROP (V)

FREQUENCY (Hz)

Dropout Voltage

vs. Output Current

Noise Performance

10

1

10

1

400

300

200

100

0

100mA

0.1

10mA

0.1

0.01

0.001

0.0001

0.01

0.001

0.0001

1mA

V_OUT= 5V

_OUT= 10µF

electrolytic

_BYP= 100pF

V_OUT= 5V

_OUT= 10µF

electrolytic

1mA

C

10mA

C

0

100 200 300 400 500

OUTPUT CURRENT (mA)

1E+11E+21E+31E+4 E+51E+61E+7

10

100

10

1k 10k 100k 1M 10M

100

FREQUENCY (Hz)

1k 10k 100k 1M 10M

FREQUENCY (Hz)

MIC5219

6

April 2001

MIC5219

Micrel

Dropout Characteristics

Ground Current

vs. Output Current

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

12

10

8

I

=100µA

L

6

I =100mA

L

4

I =500mA

L

2

0

1

2

3

4

5

6

7

8

9

0

100 200 300 400 500

OUTPUT CURRENT (mA)

INPUT VOLTAGE (V)

Ground Current

vs. Supply Voltage

Ground Current

vs. Supply Voltage

25

20

15

10

5

3.0

2.5

2.0

1.5

1.0

0.5

0

I =100 mA

L

I =100µA

I =500mA

L

0

1

2

3

4

5

6

7

8

9

0

2

4

6

8

INPUT VOLTAGE (V)

April 2001

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MIC5219

Micrel

Block Diagrams

OUT

IN

V_OUT

C_OUT

V_IN

BYP

C_BYP

(optional)

Bandgap

Ref.

V_REF

EN

Current Limit

Thermal Shutdown

MIC5219-x.xBM5/MM

GND

Ultra-Low-Noise Fixed Regulator

OUT

IN

V_OUT

C_OUT

V_IN

R1

R2

C_BYP

(optional)

Bandgap

Ref.

V_REF

EN

Current Limit

Thermal Shutdown

MIC5219BM5/MM [adj.]

GND

Ultra-Low-Noise Adjustable Regulator

MIC5219

8

April 2001

MIC5219

Micrel

Thermal Considerations

Applications Information

The MIC5219 is designed to provide 200mA of continuous

current in two very small profile packages. Maximum power

dissipationcanbecalculatedbasedontheoutputcurrentand

the voltage drop across the part. To determine the maximum

powerdissipationofthepackage,usethethermalresistance,

junction-to-ambient, of the device and the following basic

equation.

TheMIC5219isdesignedfor150mAto200mAoutputcurrent

applications where a high current spike (500mA) is needed

for short, startup conditions. Basic application of the device

will be discussed initially followed by a more detailed discus-

sion of higher current applications.

Enable/Shutdown

Forcing EN (enable/shutdown) high (> 2V) enables the regu-

lator. EN is compatible with CMOS logic. If the enable/

shutdown feature is not required, connect EN to IN (supply

input). See Figure 5.

T

– T_A

(

)

J(max)

P_D

=

(max)

θ_JA

T

is the maximum junction temperature of the die,

Input Capacitor

J(MAX)

125°C, and T is the ambient operating temperature. θ is

layout dependent; table 1 shows examples of thermal resis-

tance, junction-to-ambient, for the MIC5219.

A

JA

A 1µF capacitor should be placed from IN to GND if there is

morethan10inchesofwirebetweentheinputandtheacfilter

capacitor or if a battery is used as the input.

Package

θ_JARecommended θ_JA1" Square

Minimum Footprint 2 oz. Copper

θ_JC

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. 1µF minimum is recommended when C

(see Figure 5). 2.2µF minimum is recommended when C

MM8™ (MM)

160°C/W

220°C/W

70°C/W

30°C/W

SOT-23-5 (M5)

170°C/W

130°C/W

is not used

BYP

Table 1. MIC5219 Thermal Resistance

BYP

is 470pF (see Figure 6). For applications <3V, the output

capacitor should be increased to 22µF minimum to reduce

start-up overshoot. Larger values improve the regulator’s

transient response. The output capacitor value may be in-

creased without limit.

The actual power dissipation of the regulator circuit can be

determined using one simple equation.

P = (V – V

) I

+ V I

IN GND

D

IN

OUT OUT

Substituting P

for P and solving for the operating

D(MAX)

D

conditions that are critical to the application will give the

maximum operating conditions for the regulator circuit. For

example, if we are operating the MIC5219-3.3BM5 at room

temperature, with a minimum footprint layout, we can deter-

mine the maximum input voltage for a set output current.

The output capacitor should have an ESR (equivalent series

resistance) of about 5Ω or less and a resonant frequency

above 1MHz. Ultra-low-ESR capacitors could cause oscilla-

tion and/or underdamped transient response. Most tantalum

or aluminum electrolytic capacitors are adequate; film types

willwork, butaremoreexpensive. Manyaluminumelectrolyt-

ics have electrolytes that freeze at about –30°C, so solid

tantalums are recommended for operation below –25°C.

125°C – 25°C

(

)

P

=

D(max)

220°C/W

= 455mW

P

D(max)

At lower values of output current, less output capacitance is

needed for stability. The capacitor can be reduced to 0.47µF

for current below 10mA or 0.33µF for currents below 1mA.

The thermal resistance, junction-to-ambient, for the mini-

mum footprint is 220°C/W, taken from table 1. The maximum

power dissipation number cannot be exceeded for proper

operationofthedevice. Usingtheoutputvoltageof3.3V, and

an output current of 150mA, we can determine the maximum

input voltage. Ground current, maximum of 3mA for 150mA

of output current, can be taken from the Electrical Character-

istics section of the data sheet.

No-Load Stability

TheMIC5219willremainstableandinregulationwithnoload

(other than the internal voltage divider) unlike many other

voltage regulators. This is especially important in CMOS

RAM keep-alive applications.

Reference Bypass Capacitor

455mW = (V – 3.3V) × 150mA + V × 3mA

IN

BYP is connected to the internal voltage reference. A 470pF

455mW = (150mA) × V + 3mA × V – 495mW

IN

capacitor (C

) connected from BYP to GND quiets this

BYP

950mW = 153mA × V

IN

reference, providing a significant reduction in output noise

V

= 6.2V

MAX

IN

(ultra-low-noise performance). C

reduces the regulator

BYP

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

effectsonvoltageregulators, refertotheRegulatorThermals

sectionofMicrel’sDesigningwithLow-DropoutVoltageRegu-

lators handbook.

phase margin; when using C

or greater are generally required to maintain stability.

, output capacitors of 2.2µF

BYP

The start-up speed of the MIC5219 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

consider omitting C

. Likewise, if rapid turn-on is necessary,

.

BYP

April 2001

9

MIC5219

Micrel

Peak Current Applications

Figures3and4showsafeoperatingregionsfortheMIC5219-

x.xBMM, the power MSOP package part. These graphs

show three typical operating regions at different tempera-

tures. The lower the temperature, the larger the operating

region. The graphs were obtained in a similar way to the

graphs for the MIC5219-x.xBM5, taking all factors into con-

sideration and using two different board layouts, minimum

footprint and 1" square copper PC board heat sink. (For

furtherdiscussionofPCboardheatsinkcharacteristics, refer

to Application Hint 17, “Designing PC Board Heat Sinks”.)

The MIC5219 is designed for applications where high start-

up currents are demanded from space constrained regula-

tors. This device will deliver 500mA start-up current from a

SOT-23-5 or MM8 package, allowing high power from a very

low profile device. The MIC5219 can subsequently provide

output current that is only limited by the thermal characteris-

tics of the device. You can obtain higher continuous currents

from the device with the proper design. This is easily proved

with some thermal calculations.

Theinformationusedtodeterminethesafeoperatingregions

can be obtained in a similar manner to that used in determin-

ing typical power dissipation, already discussed. Determin-

ingthemaximumpowerdissipationbasedonthelayoutisthe

first step, this is done in the same manner as in the previous

two sections. Then, a larger power dissipation number

multiplied by a set maximum duty cycle would give that

maximum power dissipation number for the layout. This is

bestshownthroughanexample. Iftheapplicationcallsfor5V

at 500mA for short pulses, but the only supply voltage

available is 8V, then the duty cycle has to be adjusted to

determine an average power that does not exceed the

maximum power dissipation for the layout.

Ifwelookataspecificexample,itmaybeeasiertofollow. The

MIC5219 can be used to provide up to 500mA continuous

output current. First, calculate the maximum power dissipa-

tion of the device, as was done in the thermal considerations

section. Worst case thermal resistance (θ = 220°C/W for

JA

the MIC5219-x.xBM5), will be used for this example.

T

– T_A

(

)

J(max)

P_D

=

(max)

θ_JA

Assuming a 25°C room temperature, we have a maximum

power dissipation number of

125°C – 25°C

(

)

P

=

D(max)

220°C/W

= 455mW

% DC

Avg.P_D=

455mW =

0.274 =

V

– V_OUT

I

+ V_INI_GND

(

)

P

IN

OUT

D(max)

100

Then we can determine the maximum input voltage for a five-

volt regulator operating at 500mA, using worst case ground

current.

% DC

100

8V – 5V 500mA + 8V × 20mA

(

)

P

I

= 455mW = (V – V

) I

+ V I

IN GND

D(max)

IN

OUT OUT

% Duty Cycle

100

1.66W

= 500mA

OUT

V

= 5V

OUT

% Duty Cycle

100

I

= 20mA

GND

455mW = (V – 5V) 500mA + V × 20mA

IN

% Duty Cycle Max = 27.4%

2.995W = 520mA × V

IN

With an output current of 500mA and a three-volt drop across

the MIC5219-xxBMM, the maximum duty cycle is 27.4%.

2.955W

V

=

= 5.683V

IN(max)

520mA

Applications also call for a set nominal current output with a

greater amount of current needed for short durations. This is

a tricky situation, but it is easily remedied. Calculate the

average power dissipation for each current section, then add

the two numbers giving the total power dissipation for the

regulator. For example, if the regulator is operating normally

at 50mA, but for 12.5% of the time it operates at 500mA

output, the total power dissipation of the part can be easily

determined. First, calculate the power dissipation of the

device at 50mA. We will use the MIC5219-3.3BM5 with 5V

input voltage as our example.

Therefore, to be able to obtain a constant 500mA output

current from the 5219-5.0BM5 at room temperature, you

need extremely tight input-output voltage differential, barely

above the maximum dropout voltage for that current rating.

You can run the part from larger supply voltages if the proper

precautions are taken. Varying the duty cycle using the

enable pin can increase the power dissipation of the device

by maintaining a lower average power figure. This is ideal for

applications where high current is only needed in short

bursts. Figure 1 shows the safe operating regions for the

MIC5219-x.xBM5 at three different ambient temperatures

and at different output currents. The data used to determine

this figure assumed a minimum footprint PCB design for

minimum heat sinking. Figure 2 incorporates the same

factors as the first figure, but assumes a much better heat

sink. A 1" square copper trace on the PC board reduces the

thermal resistance of the device. This improved thermal

resistanceimprovespowerdissipationandallowsforalarger

safe operating region.

P × 50mA = (5V – 3.3V) × 50mA + 5V × 650µA

D

P × 50mA = 173mW

D

However, this is continuous power dissipation, the actual

on-time for the device at 50mA is (100%-12.5%) or 87.5% of

the time, or 87.5% duty cycle. Therefore, P must be

D

multiplied by the duty cycle to obtain the actual average

power dissipation at 50mA.

MIC5219

10

April 2001

MIC5219

Micrel

10

8

10

8

10

8

100mA

200mA

6

200mA

4

300mA

400mA

20

2

500mA

400mA

20

500mA

40

500mA

40

DUTY CYCLE (%)

0

60

80

100

0

60

80

100

0

20

40

60

80

100

DUTY CYCLE (%)

a. 25°C Ambient

b. 50°C Ambient

c. 85°C Ambient

Figure 1. MIC5219-x.xBM5 (SOT-23-5) on Minimum Recommended Footprint

10

8

10

8

10

8

100mA

200mA

6

200mA

300mA

4

300mA

80

400mA

20

2

300mA

400mA

20

400mA

500mA

20 40

500mA

40 60

500mA

40 60

0

80

100

0

100

0

60

80

100

DUTY CYCLE (%)

a. 25°C Ambient

b. 50°C Ambient

c. 85°C Ambient

2

Figure 2. MIC5219-x.xBM5 (SOT-23-5) on 1-inch Copper Cladding

10

8

10

8

10

8

100mA

300mA

100mA

200mA

6

200mA

300mA

4

400mA

20

400mA

20

2

400mA

500mA

40 60

500mA

40

500mA

20 40

DUTY CYCLE (%)

0

80

100

0

60

80

100

0

60

80

100

DUTY CYCLE (%)

a. 25°C Ambient

b. 50°C Ambient

c. 85°C Ambient

Figure 3. MIC5219-x.xBMM (MSOP-8) on Minimum Recommended Footprint

10

8

10

8

10

8

200mA

300mA

100mA

200mA

300mA

200mA

6

400mA

300mA

400mA

4

400mA

20

500mA

2

500mA

2

500mA

40 60

0

20

40

60

80

100

0

20

40

60

80

100

0

80

100

DUTY CYCLE (%)

a. 25°C Ambient

b. 50°C Ambient

c. 85°C Ambient

2

Figure 4. MIC5219-x.xBMM (MSOP-8) on 1-inch Copper Cladding

April 2001

11

MIC5219

Micrel

MIC5219-x.x

P × 50mA = 0.875 × 173mW

D

V_IN

V_OUT

P × 50mA = 151mW

IN

OUT

BYP

GND

D

EN

The power dissipation at 500mA must also be calculated.

2.2µF

P × 500mA = (5V – 3.3V) 500mA + 5V × 20mA

D

470pF

P × 500mA = 950mW

D

This number must be multiplied by the duty cycle at which it

would be operating, 12.5%.

Figure 6. Ultra-Low-Noise Fixed Voltage Regulator

P × = 0.125 × 950mW

Figure 6 includes the optional 470pF noise bypass capacitor

between BYP and GND to reduce output noise. Note that the

D

P × = 119mW

D

minimum value of C

capacitor is used.

must be increased when the bypass

OUT

The total power dissipation of the device under these condi-

tions is the sum of the two power dissipation figures.

Adjustable Regulator Circuits

P

= P × 50mA + P × 500mA

D D

D(total)

MIC5219

= 151mW + 119mW

= 270mW

V_IN

V_OUT

1µF

IN

OUT

ADJ

GND

R1

R2

EN

The total power dissipation of the regulator is less than the

maximum power dissipation of the SOT-23-5 package at

room temperature, on a minimum footprint board and there-

fore would operate properly.

Multilayer boards with a ground plane, wide traces near the

pads, and large supply-bus lines will have better thermal

conductivity.

Figure 7. Low-Noise Adjustable Voltage Regulator

Figure 7 shows the basic circuit for the MIC5219 adjustable

regulator. The output voltage is configured by selecting

values for R1 and R2 using the following formula:

For additional heat sink characteristics, please refer to Micrel

Application Hint 17, “Designing P.C. Board Heat Sinks”,

included in Micrel’s Databook. For a full discussion of heat

sinking and thermal effects on voltage regulators, refer to

Regulator Thermals section of Micrel’s Designing with Low-

Dropout Voltage Regulators handbook.

R2

V

= 1.242V

+1

OUT

R1

Although ADJ is a high-impedance input, for best perfor-

Fixed Regulator Circuits

MIC5219-x.x

mance, R2 should not exceed 470kΩ.

MIC5219

V_IN

V_OUT

1µF

V_IN

V_OUT

IN

OUT

BYP

IN

OUT

ADJ

GND

R1

R2

EN

GND

2.2µF

470pF

Figure 5. Low-Noise Fixed Voltage Regulator

Figure 8. Ultra-Low-Noise Adjustable Application.

Figure5showsabasicMIC5219-x.xBMXfixed-voltageregu-

lator circuit. A 1µF minimum output capacitor is required for

basic fixed-voltage applications.

Figure 8 includes the optional 470pF bypass capacitor from

ADJ to GND to reduce output noise.

MIC5219

12

April 2001

MIC5219

Micrel

Package Information

0.122 (3.10)

0.112 (2.84)

0.199 (5.05)

0.187 (4.74)

DIMENSIONS:

INCH (MM)

0.120 (3.05)

0.116 (2.95)

0.036 (0.90)

0.032 (0.81)

0.043 (1.09)

0.038 (0.97)

0.012 (0.30) R

0.007 (0.18)

0.005 (0.13)

0.008 (0.20)

0.004 (0.10)

5° MAX

0° MIN

0.012 (0.03)

0.012 (0.03) R

0.039 (0.99)

0.0256 (0.65) TYP

0.035 (0.89)

0.021 (0.53)

8-Pin MSOP (MM)

1.90 (0.075) REF

0.95 (0.037) REF

1.75 (0.069) 3.00 (0.118)

1.50 (0.059) 2.60 (0.102)

DIMENSIONS:

MM (INCH)

1.30 (0.051)

0.90 (0.035)

3.02 (0.119)

2.80 (0.110)

0.20 (0.008)

0.09 (0.004)

10°

0°

0.15 (0.006)

0.00 (0.000)

0.50 (0.020)

0.35 (0.014)

0.60 (0.024)

0.10 (0.004)

SOT-23-5 (M5)

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.

April 2001

13

MIC5219


型号：	MIC5219_01
厂家：	MICREL SEMICONDUCTOR
描述：	500mA-Peak Output LDO Regulator 值为500mA的峰值输出LDO稳压器稳压器
文件：	总13页 (文件大小：97K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MIC5219_01 [MICREL]

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