Datasheet MIC5219 Datasheet (Micrel)

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Page 1

MIC5219 Micrel, Inc.

2.2µF tantalum

470pF

OUT

3.3V

MIC5219-3.3BM5

ENABLE

SHUTDOWN

MIC5219

500mA-Peak Output LDO Regulator

General Description

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.

The MIC5219 is designed to provide a peak output current for start-up 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 help prolong battery life. Other key features include reversedbattery protection, current limiting, overtemperature shutdown, and low noise performance with an ultra-low-noise option.

The MIC5219 is available in adjustable or fixed output voltages in the space-saving 6-pin (2mm × 2mm) MLF™, SOT-23-5 and MM8™ 8-pin power MSOP packages. For higher power requirements see the MIC5209 or MIC5237.

All support documentation can be found on Micrel’s web site at www.micrel.com.

Features

• 500mA output current capability

SOT-23-5 package - 500mA peak

××

2mm

×2mm MLF package - 500mA continuous

××

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

Applications

• Laptop, notebook, and palmtop computers

• Cellular telephones and battery-powered equipment

• Consumer and personal electronics

• PC Card VCC and VPP regulation and switching

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

•High-efficiency linear power supplies

Typical Applications

MIC5219-5.0BMM

ENABLE

HUTDOWN

OUT

2.2µF

tantalum

470pF

5V Ultra-Low-Noise Regulator

ENABLE

SHUTDOWN

MM8 is a trademark of Micrel, Inc.

MicroLeadFrame and MLF are trademarks of Amkor Technology.

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 474-1000 • fax + 1 (408) 474-1000 • http://www.micrel.com

March 2005 1 M999-031205

MIC5219-x.xBML

Ultra-Low-Noise Regulator

3.3V Ultra-Low-Noise Regulator

OUT

BYP

(optional)

OUT

Page 2

MIC5219 Micrel, Inc.

OUTBYP

LGxx

GND

Part Identification

OUTADJ

LGAA

GND

Ordering Information

Part Number Marking

Standard Pb-Free Standard Pb-Free Volts Temp. Range Package

MIC5219-2.5BMM MIC5219-2.5YMM — — 2.5V –40°C to +125°C MSOP-8

MIC5219-2.85BMM MIC5219-2.85YMM — — 2.85V –40°C to +125°C MSOP-8

MIC5219-3.0BMM MIC5219-3.0YMM — — 3.0V –40°C to +125°C MSOP-8

MIC5219-3.3BMM MIC5219-3.3YMM — — 3.3V –40°C to +125°C MSOP-8

MIC5219-3.6BMM MIC5219-3.6YMM — — 3.6V –40°C to +125°C MSOP-8

MIC5219-5.0BMM MIC5219-5.0YMM — — 5.0V –40°C to +125°C MSOP-8

MIC5219BMM MIC5219YMM — — Adj. –40°C to +125°C MSOP-8

MIC5219-2.5BM5 MIC5219-2.5YM5 LG25 LG25* 2.5V –40°C to +125°C SOT-23-5

MIC5219-2.6BM5 MIC5219-2.6YM5 LG26 LG26 2.6V –40°C to +125°C SOT-23-5

MIC5219-2.7BM5 MIC5219-2.7YM5 LG27 LG27 2.7V –40°C to +125°C SOT-23-5

MIC5219-2.8BM5 MIC5219-2.8YM5 LG28 LG28 2.8V –40°C to +125°C SOT-23-5

MIC5219-2.8BML MIC5219-2.8YML G28 G28* 2.8V –40°C to +125°C 6-Pin 2×2 MLF

MIC5219-2.85BM5 MIC5219-2.85YM5 LG2J LG2J 2.85V –40°C to +125°C SOT-23-5

MIC5219-2.9BM5 MIC5219-2.9YM5 LG29 LG29 2.9V –40°C to +125°C SOT-23-5

MIC5219-3.1BM5 MIC5219-3.1YM5 LG31 LG31 3.1V –40°C to +125°C SOT-23-5

MIC5219-3.0BM5 MIC5219-3.0YM5 LG30 LG30 3.0V –40°C to +125°C SOT-23-5

MIC5219-3.0BML MIC5219-3.0YML G30 G30* 3.0V –40°C to +125°C 6-Pin 2×2 MLF

MIC5219-3.3BM5 MIC5219-3.3YM5 LG33 LG33 3.3V –40°C to +125°C SOT-23-5

MIC5219-3.3BML MIC5219-3.3YML G33 G33* 3.3V –40°C to +125°C 6-Pin 2×2 MLF

MIC5219-3.6BM5 MIC5219-3.6YM5 LG36 LG36 3.6V –40°C to +125°C SOT-23-5

MIC5219-5.0BM5 MIC5219-5.0YM5 LG50 LG50 5.0V –40°C to +125°C SOT-23-5

MIC5219BM5 MIC5219YM5 LGAA LGAA Adj. –40°C to +125°C SOT-23-5

Other voltages available. Consult Micrel for details. *Overbar symbol (_) may not be to scale. Physical symbol is after Pin 1 identifier.

™

Pin Configuration

OUT

BYP

MIC5219-x.xBMM

MM8™ MSOP-8

Fixed Voltages

(Top View)

OUT

ADJ

MIC5219YMM MIC5219BMM

MM8™ MSOP-8

Adjustable Voltage

(Top View)

M999-031205 2 March 2005

GND

1EN

GND

MIC5219-x.xBML

6-Pin 2mm

6 BYP

OUT

××

× 2mm MLF™ (ML)

××

(Top View)

MIC5219-x.xBM5

SOT-23-5

Fixed Voltages

(Top View)

MIC5219BM5

SOT-23-5

Adjustable Voltage

(Top View)

Page 3

MIC5219 Micrel, Inc.

Pin Description

Pin No. Pin No. Pin No. Pin Name Pin Function

MLF™-6 MSOP-8 SOT-23-5

321 IN Supply Input.

2 5–8 2 GND Ground: MSOP-8 pins 5 through 8 are internally connected.

435OUT Regulator Output.

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

low or open = shutdown.

64 (fixed) 4 (fixed) BYP Reference Bypass: Connect external 470pF capacitor to GND to reduce

output noise. May be left open.

5(NC) 4 (adj.) 4 (adj.) ADJ Adjust (Input): Feedback input. Connect to resistive voltage-divider network.

EP — — GND Ground: Internally connected to the exposed pad. Connect externally to

GND pin.

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MIC5219 Micrel, Inc.

Absolute Maximum Ratings

(1)

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

Power Dissipation (P Junction Temperature (T

) ............................ Internally Limited

) ....................... –40°C to +125°C

Storage Temperature (TS) ....................... –65°C to +150°C

Operating Ratings

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

Enable Input Voltage (V

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

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

(2)

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

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

(6)

(3)

= 100µA; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.

OUT

–1 1 %

–2 2 %

(7, 8)

(8)

OUT

+ 1V to 12V 0.009 0.05 %/V

OUT

= 100µA to 500mA, Note 5 0.05 0.5 %

OUT

= 100µA1060mV

OUT

= 50mA 115 175 mV

OUT

= 150mA 175 300 mV

OUT

= 500mA 350 500 mV

OUT

VEN ≥ 3.0V, I

≥ 3.0V, I

= 100µA80130 µA

OUT

= 50mA 350 650 µA

OUT

= 150mA 1.8 2.5 mA

OUT

= 500mA 12 20 mA

OUT

VEN ≤ 0.4V 0.05 3 µA

VEN ≤ 0.18V 0.10 8 µA

= 0V 700 1000 mA

OUT

= 50mA, C

OUT

= 50mA, C

OUT

= 2.2µF, C

OUT

= 2.2µF, C

OUT

= 0 500

BYP

= 470pF 300

BYP

VEN = logic high (regulator enabled) 2.0 V

≤ 0.4V 0.01 –1 µA

ENL

≤ 0.18V 0.01 –2 µA

ENL

≥ 2.0V 2 5 20 µA

ENH

0.1

0.7

250

400

600

170

900

3.0

nV/ Hz

0.18

Electrical Characteristics

VIN = V

Symbol Parameter Conditions Min Typical Max Units

OUT

∆V

OUT

∆V

OUT/VOUT

∆V

OUT/VOUT

– V

GND

PSRR Ripple Rejection f = 120Hz 75 dB

LIMIT

∆V

OUT

ENABLE Input

ENL

ENH

+ 1.0V; C

OUT

= 4.7µF, I

OUT

Output Voltage Accuracy variation from nominal V

/∆T Output Voltage Note 4 40 ppm/°C

Temperature Coefficient

Line Regulation VIN = V

Load Regulation I

OUT

Dropout Voltage

Ground Pin Current

Ground Pin Quiescent Current

Current Limit V

/∆P

Thermal Regulation Note 9 0.05 %/W

Output Noise

(10)

Enable Input Logic-Low Voltage VEN = logic low (regulator shutdown) 0.4 V

Enable Input Current V

M999-031205 4 March 2005

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MIC5219 Micrel, Inc.

Notes:

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, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P temperature, and the regulator will go into thermal shutdown. See Table 1 and the “Thermal Considerations” section for details.

(max) = (TJ(max) – TA) ÷ θJA. Exceeding the maximum allowable power dissipation will result in excessive die

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

3. Specification for packaged product only.

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

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

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.

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.

8. V

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

9. 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 VIN = 12V for t = 10ms.

10. C

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

BYP

(max),

March 2005 5 M999-031205

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MIC5219 Micrel, Inc.

-100

-80

-60

-40

-20

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

-100

-80

-60

-40

-20

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

0.0001

0.001

0.01

0.1

1E+1 1E+2 1E+31E+4 1E+51E+6 1E+7

NOISE (µV/√Hz)

FREQUENCY (Hz)

100

200

300

400

0 100 200 300 400 500

DROPOUT VOLTAGE (mV)

OUTPUT CURRENT (mA)

Typical Characteristics

Power Supply

Rejection Ratio

-20

VIN = 6V V

= 5V

OUT

-40

-60

PSRR (dB)

-80

-100

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

= 100µA

OUT

= 1µF

OUT

10k

100k

Power Supply

Rejection Ratio

VIN = 6V V

= 5V

OUT

-20

-40

-60

PSRR (dB)

-80

-100

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

= 100µA

OUT

= 2.2µF

OUT

= 0.01µF

BYP

10k

100k

10M

Power Supply

Rejection Ratio

-20

VIN = 6V V

= 5V

OUT

-40

-60

PSRR (dB)

-80

-100

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

= 1mA

OUT

= 1µF

OUT

10k

100k

Power Supply

Rejection Ratio

VIN = 6V V

= 5V

OUT

-20

-40

-60

PSRR (dB)

-80

-100

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

100

= 1mA

OUT

= 2.2µF

OUT

= 0.01µF

BYP

10k

FREQUENCY (Hz)

100k

10M

VIN = 6V V

OUT

100

VIN = 6V V

OUT

100

Power Supply

Rejection Ratio

= 5V

= 100mA

OUT

= 1µF

OUT

10k

100k

Power Supply

Rejection Ratio

= 5V

= 100mA

OUT

= 2.2µF

OUT

= 0.01µF

BYP

10k

100k

10M

Power Supply Ripple Rejection

vs. Voltage Drop

1mA

RIPPLE REJECTION (dB)

0.1

0.01

NOISE (µV/√Hz)

0.001

0.0001

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

10mA

= 100mA

OUT

0 0.1 0.2 0.3 0.4

VOLTAGE DROP (V)

OUT

Noise Performance

V C electrolytic

OUT

100

= 5V = 10µF

FREQUENCY (Hz)

100mA

1mA

10k 100k1M10M

= 1µF

10mA

Power Supply Ripple Rejection

100

RIPPLE REJECTION (dB)

0.1

0.01

NOISE (µV/√Hz)

0.001

0.0001

vs. Voltage Drop

90 80

1mA 70 60

50 40

10mA 30 20

00.10.20.3 0.4

VOLTAGE DROP (V)

Noise Performance

= 5V

OUT

= 10µF

OUT

electrolytic C

= 100pF

BYP

1E+11E+2 1E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

OUT

= 2.2µF

OUT

= 0.01µF

BYP

1mA

10mA

10k 100k1M10M

= 100mA

100mA

Noise Performance

10mA, C

100

Dropout Voltage

vs. Output Current

= 1µF

OUT

= 5V

OUT

10k 100k 1M 10M

M999-031205 6 March 2005

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MIC5219 Micrel, Inc.

0123456789

GROUND CURRENT (mA)

INPUT VOLTAGE (V)

Dropout Characteristics

3.5 IL =100µA

3.0

2.5

2.0

1.5

1.0

OUTPUT VOLTAGE (V)

0.5

IL=100mA

IL=500mA

0123456789

INPUT VOLTAGE (V)

Ground Current

vs. Output Current

GROUND CURRENT (mA)

0 100 200 300 400 500

OUTPUT CURRENT (mA)

Ground Current

vs. Supply Voltage

3.0

2.5

2.0

1.5

1.0

0.5

GROUND CURRENT (mA)

02468

INPUT VOLTAGE (V)

IL=100 mA

IL=100µA

Ground Current

vs. Supply Voltage

IL=500mA

March 2005 7 M999-031205

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MIC5219 Micrel, Inc.

Block Diagrams

BYP

(optional)

BYP

Bandgap

Ref.

REF

Current Limit

Thermal Shutdown

MIC5219-x.xBM5/MM

Ultra-Low-Noise Fixed Regulator

Bandgap

Ref.

REF

GND

OUT

C (optional)

BYP

OUT

Current Limit

Thermal Shutdown

MIC5219BM5/MM [adj.]

GND

Ultra-Low-Noise Adjustable Regulator

M999-031205 8 March 2005

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MIC5219 Micrel, Inc.

Applications Information

The MIC5219 is designed for 150mA to 200mA output current applications where a high current spike (500mA) is needed for short, start-up conditions. Basic application of the device will be discussed initially followed by a more detailed discussion of higher current applications.

Enable/Shutdown

Forcing EN (enable/shutdown) high (>2V) enables the regulator. EN is compatible with CMOS logic. If the enable/ shutdown feature is not required, connect EN to IN (supply input). See Figure 5.

Input Capacitor

A 1µF 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.

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 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 increased without limit.

The output capacitor should have an ESR (equivalent series resistance) of about 1Ω or less and a resonant frequency above 1MHz. Ultra-low-ESR capacitors could cause oscillation and/or underdamped transient response. Most tantalum or aluminum electrolytic capacitors are adequate; film types will work, but are more expensive. Many aluminum electrolytics have electrolytes that freeze at about –30°C, so solid tantalums are recommended for operation below –25°C.

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.

No-Load Stability

The MIC5219 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.

Reference Bypass Capacitor

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

) connected from BYP to GND quiets this

BYP

reference, providing a significant reduction in output noise (ultra-low-noise performance). C phase margin; when using C

BYP

reduces the regulator

BYP

, output capacitors of 2.2µF

or greater are generally required to maintain stability.

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

is not used

BYP

Thermal Considerations

The MIC5219 is designed to provide 200mA of continuous current in two very small profile packages. 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 thermal resistance, junction-to-ambient, of the device and the following basic equation.

T max T

()=−

()

P max

()

TJ(max) is the maximum junction temperature of the die, 125°C, and T

is the ambient operating temperature. θJA is

layout dependent; Table 1 shows examples of thermal resistance, junction-to-ambient, for the MIC5219.

Package

MM8™ (MM) 160°C/W 70°C/W 30°C/W

SOT-23-5 (M5) 220°C/W 170°C/W 130°C/W

2×2 MLF™ (ML) 90°C/W — —

θθ

θJA Recommended

θθ

Minimum Footprint 2oz. Copper

θθ

θJA 1" Square

θθ

Table 1. MIC5219 Thermal Resistance

The actual power dissipation of the regulator circuit can be determined using one simple equation.

PD = (VIN – V

OUT

) I

OUT

+ VIN I

GND

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, if we are operating the MIC5219-3.3BM5 at room temperature, with a minimum footprint layout, we can determine the maximum input voltage for a set output current.

125 C 25 C

° − °

Pmax

()/=

()

220 C W

PD(max) = 455mW

The thermal resistance, junction-to-ambient, for the minimum footprint is 220°C/W, taken from Table 1. The maximum power dissipation number cannot be exceeded for proper operation of the device. Using the output voltage of 3.3V, 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.

455mW = (VIN – 3.3V) × 150mA + VIN × 3mA

455mW = (150mA) × VIN + 3mA × VIN – 495mW

950mW = 153mA × V

VIN = 6.2V

MAX

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.

March 2005 9 M999-031205

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MIC5219 Micrel, Inc.

Peak Current Applications

The MIC5219 is designed for applications where high startup currents are demanded from space constrained regulators. 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 characteristics of the device. You can obtain higher continuous currents from the device with the proper design. This is easily proved with some thermal calculations.

If we look at a specific example, it may be easier to follow. The MIC5219 can be used to provide up to 500mA continuous output current. First, calculate the maximum power dissipation of the device, as was done in the thermal considerations section. Worst case thermal resistance (θJA = 220°C/W for the MIC5219-x.xBM5), will be used for this example.

T max T

()=−

()

P max

()

Assuming a 25°C room temperature, we have a maximum power dissipation number of

P max

()/=

PD(max) = 455mW

Then we can determine the maximum input voltage for a 5volt regulator operating at 500mA, using worst case ground current.

PD(max) = 455mW = (VIN – V

= 500mA

OUT

= 5V

OUT

= 20mA

GND

455mW = (VIN – 5V) 500mA + VIN × 20mA

2.995W = 520mA × V

V max

()

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

125 C 25 C

° − °

()

220 C W

) I

OUT

+ VIN I

GND

2 955W

5 683V

.==

OUT

520mA

resistance improves power dissipation and allows for a larger safe operating region.

Figures 3 and 4 show safe operating regions for the MIC5219x.xBMM, the power MSOP package part. These graphs show three typical operating regions at different temperatures. 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 consideration and using two different board layouts, minimum footprint and 1" square copper PC board heat sink. (For further discussion of PC board heat sink characteristics, refer to “Application Hint 17, Designing PC Board Heat Sinks” .)

The information used to determine the safe operating regions can be obtained in a similar manner such as determining typical power dissipation, already discussed. Determining the maximum power dissipation based on the layout is the 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 best shown through an example. If the application calls for 5V 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.

% DC

Avg.P =

455mW =

0.274 =

% Duty Cycle Max = 7.4%2

With an output current of 500mA and a three-volt drop across the MIC5219-xxBMM, the maximum duty cycle is 27.4%.

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.

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

PD × 50mA = 173mW

 

DIN



% Duty Cycle



V – V I V I



()



100

% DC

  



8V – 5V 500mA 8V 20mA

()

 

100

% Duty Cycle

  

100

OUT OUT



1.66W

 

GND

+×

M999-031205 10 March 2005

Page 11

MIC5219 Micrel, Inc.

020406080100

VOLTAGE DROP (V)

DUTY CYCLE (%)

020406080100

VOLTAGE DROP (V)

DUTY CYCLE (%)

020406080100

VOLTAGE DROP (V)

DUTY CYCLE (%)

020406080100

VOLTAGE DROP (V)

DUTY CYCLE (%)

400mA

VOLTAGE DROP (V)

020406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

VOLTAGE DROP (V)

400mA

020406080100

100mA

200mA

300mA

500mA

DUTY CYCLE (%)

100mA

200mA

500mA

400mA

a. 25°C Ambient b. 50°C Ambient c. 85°C Ambient

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

400mA

VOLTAGE DROP (V)

020406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

VOLTAGE DROP (V)

400mA

020406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

100mA

400mA

500mA

a. 25°C Ambient b. 50°C Ambient c. 85°C Ambient

300mA

200mA

300mA

Figure 2. MIC5219-x.xBM5 (SOT-23-5) on 1-inch2 Copper Cladding

400mA

VOLTAGE DROP (V)

020406080100

500mA

DUTY CYCLE (%)

100mA

200mA

300mA

400mA

VOLTAGE DROP (V)

020406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

100mA

400mA

500mA

a. 25°C Ambient b. 50°C Ambient c. 85°C Ambient

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

VOLTAGE DROP (V)

020406080100

400mA

DUTY CYCLE (%)

200mA

300mA

500mA

400mA

VOLTAGE DROP (V)

020406080100

DUTY CYCLE (%)

200mA

300mA

500mA

400mA

500mA

a. 25°C Ambient b. 50°C Ambient c. 85°C Ambient

Figure 4. MIC5219-x.xBMM (MSOP-8) on 1-inch2 Copper Cladding

200mA

300mA

100mA

200mA

300mA

March 2005 11 M999-031205

Page 12

MIC5219 Micrel, Inc.

MIC5219-x.x

IN OUT

GND

470pF

EN BYP

2.2µF

OUT

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, PD must be multiplied by the duty cycle to obtain the actual average power dissipation at 50mA.

PD × 50mA = 0.875 × 173mW

PD × 50mA = 151mW

The power dissipation at 500mA must also be calculated.

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

PD × 500mA = 950mW

This number must be multiplied by the duty cycle at which it would be operating, 12.5%.

PD × = 0.125 × 950mW

PD × = 119mW

The total power dissipation of the device under these conditions is the sum of the two power dissipation figures.

= PD × 50mA + PD × 500mA

D(total)

= 151mW + 119mW

D(total)

= 270mW

D(total)

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 therefore would operate properly.

Multilayer boards with a ground plane, wide traces near the pads, and large supply-bus lines will have better thermal conductivity.

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.

Fixed Regulator Circuits

MIC5219-x.x

IN OUT

EN BYP

GND

1µF

OUT

Figure 5 shows a basic MIC5219-x.xBMX fixed-voltage regulator circuit. A 1µF minimum output capacitor is required for basic fixed-voltage applications.

Figure 6. Ultra-Low-Noise Fixed Voltage Regulator

Figure 6 includes the optional 470pF noise bypass capacitor between BYP and GND to reduce output noise. Note that the minimum value of C

must be increased when the bypass

OUT

capacitor is used.

Adjustable Regulator Circuits

MIC5219

IN OUT

EN ADJ

GND

1µF

OUT

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:



 

V 1.242V

OUT

  

Although ADJ is a high-impedance input, for best performance, R2 should not exceed 470kΩ.

MIC5219

IN OUT

EN ADJ

GND

470pF

OUT

2.2µF

Figure 8. Ultra-Low-Noise Adjustable Application

Figure 5. Low-Noise Fixed Voltage Regulator

Figure 8 includes the optional 470pF bypass capacitor from ADJ to GND to reduce output noise.

M999-031205 12 March 2005

Page 13

MIC5219 Micrel, Inc.



Package Information

0.122 (3.10)

0.112 (2.84)

0.036 (0.90)

0.032 (0.81)

0.012 (0.03)

0.0256 (0.65) TYP

1.90 (0.075) REF

0.95 (0.037) REF

3.02 (0.119)

2.80 (0.110)

0.199 (5.05)

0.187 (4.74)

0.120 (3.05)

0.116 (2.95)

0.043 (1.09)

0.038 (0.97)

0.008 (0.20)

0.004 (0.10)

8-Pin MSOP (MM)

1.75 (0.069)

1.50 (0.059)

1.30 (0.051)

0.90 (0.035)

0.012 (0.30) R

5° MAX

0° MIN

3.00 (0.118)

2.60 (0.102)

10°

0°

DIMENSIONS:

INCH (MM)

0.039 (0.99)

0.035 (0.89)

0.021 (0.53)

DIMENSIONS:

MM (INCH)

0.007 (0.18)

0.005 (0.13)

0.012 (0.03) R

0.20 (0.008)

0.09 (0.004)

0.50 (0.020)

0.35 (0.014)

0.15 (0.006)

0.00 (0.000)

SOT-23-5 (M5)

0.60 (0.024)

0.10 (0.004)

March 2005 13 M999-031205

Page 14

MIC5219 Micrel, Inc.

TOP VIEW BOTTOM VIEW

Dimensions in

millimeter

6-Pin MLF™ (ML)

SIDE VIEW

Rev. 01

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 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

M999-031205 14 March 2005

Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel for any damages resulting from such use or sale.