Datasheet MIC5219-3.0BMM, MIC5219-3.3BM5, MIC5219-3.3BMM, MIC5219-2.7BM5, MIC5219-2.8BM5 Datasheet (MICREL)

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Page 1

MIC5219 Micrel

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 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 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 space-saving SOT-23-5 and MM8™ 8-lead power MSOP packages. For higher power requirements see the MIC5209 or MIC5237.

Features

• Guaranteed 500mA-peak output over the full operating temperature range

• 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

1 2 3 4

470pF

5V 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

July 2000 1 MIC5219

8 7 6 5

ENABLE

SHUTDOWN

MIC5219-3.3BM5

15 2 3

3.3V

OUT

2.2µF tantalum

470pF

3.3V Ultra-Low-Noise Regulator

Page 2

MIC5219 Micrel

Ordering Information

Part Number Marking Volts Junction Temp. Range Package

MIC5219-3.0BMM — 3.0V –40°C to +125°C MSOP-8 MIC5219-3.3BMM — 3.3V –40°C to +125°C MSOP-8 MIC5219-3.6BMM — 3.6V –40°C to +125°C MSOP-8 MIC5219-5.0BMM — 5.0V –40°C to +125°C MSOP-8 MIC5219BMM — Adj. –40°C to +125°C MSOP-8 MIC5219-2.6BM5 LG26 2.6V –40°C to +125°C SOT-23-5 MIC5219-2.7BM5 LG27 2.7V –40°C to +125°C SOT-23-5 MIC5219-2.8BM5 LG28 2.8V –40°C to +125°C SOT-23-5 MIC5219-2.9BM5 LG29 2.9V –40°C to +125°C SOT-23-5 MIC5219-3.0BM5 LG30 3.0V –40°C to +125°C SOT-23-5 MIC5219-3.3BM5 LG33 3.3V –40°C to +125°C SOT-23-5 MIC5219-3.6BM5 LG36 3.6V –40°C to +125°C SOT-23-5 MIC5219-5.0BM5 LG50 5.0V –40°C to +125°C SOT-23-5 MIC5219BM5 LGAA Adj. –40°C to +125°C SOT-23-5

Other voltages available. Consult Micrel for details.

Pin Configuration

OUT

BYP

OUT

ADJ

Adjustable Voltage

Pin Description

8 7 6 5

MIC5219-x.xBMM

MM8™ MSOP-8

Fixed Voltages

8 7 6 5

MIC5219BMM

MM8™ MSOP-8

GND GND GND GND

GND

LGxx

OUTBYP

MIC5219-x.xBM5

SOT-23-5

Fixed Voltages

GND

LGAA

OUTADJ

MIC5219BM5

SOT-23-5

Adjustable Voltage

Part Identification

Pin No. Pin No. Pin Name Pin Function

MSOP-8 SOT-23-5

2 1 IN Supply Input

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

3 5 OUT Regulator Output 1 3 EN Enable (Input): CMOS compatible control input. Logic high = enable; logic

low or open = shutdown.

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

output noise. May be left open.

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

MIC5219 2 July 2000

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MIC5219 Micrel

Absolute Maximum Ratings

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

Power Dissipation (P Junction Temperature (T

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

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

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

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

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 I

LIMIT

∆V

OUT

ENABLE Input

ENL

ENH

+ 1.0V; C

OUT

Output Voltage Accuracy variation from nominal V

= 4.7µF, I

OUT

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

OUT

–11%

–22%

/∆T Output Voltage Note 2 40 ppm/°C

Temperature Coefficient Line Regulation VIN = V

+ 1V to 12V 0.009 0.05 %/V

OUT

0.1

OUT

Load Regulation I

Dropout Voltage, Note 4 I

= 100µA to 500mA Note 3 0.05 0.5 %

OUT

= 100µA1060mV

OUT

= 50mA 115 175 mV

OUT

= 150mA 175 300 mV

OUT

= 500mA 350 500 mV

OUT

0.7

250

400

600

Ground Pin Current, Notes 5, 6 VEN ≥ 3.0V, I

= 100µA80130µA

OUT

170

≥ 3.0V, I

= 50mA 350 650 µA

OUT

900

≥ 3.0V, I

= 150mA 1.8 2.5 mA

OUT

3.0

≥ 3.0V, I

= 500mA 12 20 mA

OUT

Ground Pin Quiescent Current, VEN ≤ 0.4V 0.05 3 µA Note 6

Current Limit V

VEN ≤ 0.18V 0.10 8 µA

= 0V 700 1000 mA

OUT

/∆PDThermal Regulation Note 7 0.05 %/W

Output Noise I

= 50mA, C

OUT

= 50mA, C

OUT

= 2.2µF, C

OUT

= 2.2µF, C

OUT

= 0 500

BYP

= 470pF 300

BYP

nV/ Hz nV/ Hz

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

0.18

VEN = logic high (regulator enabled) 2.0 V

Enable Input Current V

≤ 0.4V 0.01 –1 µA

ENL

≤ 0.18V 0.01 –2 µA

ENL

≥ 2.0V 2 5 20 µA

ENH

July 2000 3 MIC5219

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MIC5219 Micrel

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

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

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

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

Note 6: VEN is the voltage externally applied to devices with the EN (enable) input pin. 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

Note 8: C

operating the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, T dissipation at any ambient temperature is calculated using: P tion will result in excessive die temperature, and the regulator will go into thermal shutdown. See Table 1 and the “Thermal Considerations”

, the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power

J(max)

D(max)

= (T

– TA) ÷ θJA. Exceeding the maximum allowable power dissipa-

J(max)

section for details.

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

differential.

the load current plus the ground pin current.

regulation effects. Specifications are for a 500mA load pulse at VIN = 12V for t = 10ms.

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

BYP

MIC5219 4 July 2000

Page 5

MIC5219 Micrel

-100

-80

-60

-40

-20

1E+11E+21E+31E+4 1E+51E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100mA

OUT

= 1µF

VIN = 6V V

OUT

= 5V

100

10k

100k

10M

-100

-80

-60

-40

-20

1E+11E+21E+31E+4 1E+51E+6 1E+7

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

OUT

= 100mA

OUT

= 2.2µF

BYP

= 0.01µF

VIN = 6V V

OUT

= 5V

100

10k

100k

10M

100

0 0.1 0.2 0.3 0.4

RIPPLE REJECTION (dB)

VOLTAGE DROP (V)

√

0.0001

0.001

0.01

0.1

1E+11E+21E+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)

Dropout Voltage

vs. Output Current

Typical Characteristics

Power Supply

Rejection Ratio

-20

VIN = 6V V

= 5V

OUT

-40

-60

PSRR (dB)

-80

-100

1E+11E+21E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

= 100µA

OUT

= 1µF

OUT

10k

100k

Power Supply

Rejection Ratio

VIN = 6V V

-20

-40

-60

PSRR (dB)

-80

-100

= 5V

OUT

= 100µA

OUT

= 2.2µF

OUT

= 0.01µF

BYP

1E+11E+21E+31E+4 1E+51E+6 1E+7

100

10k

FREQUENCY (Hz)

100k

10M

Power Supply

Rejection Ratio

-20

VIN = 6V V

= 5V

OUT

-40

-60

PSRR (dB)

-80

-100

1E+11E+21E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

= 1mA

OUT

= 1µF

OUT

10k

100k

Power Supply

Rejection Ratio

VIN = 6V V

-20

-40

-60

PSRR (dB)

-80

-100

= 5V

OUT

= 1mA

OUT

= 2.2µF

OUT

= 0.01µF

BYP

1E+11E+21E+31E+4 1E+51E+6 1E+7

100

10k

FREQUENCY (Hz)

100k

10M

RIPPLE REJECTION (dB)

Hz)

0.1

July 2000 5 MIC5219

0.01

NOISE (µV/

0.001

0.0001

Power Supply Ripple Rejection

vs. Voltage Drop

1mA

10mA

= 100mA

OUT

= 1µF

0 0.1 0.2 0.3 0.4

VOLTAGE DROP (V)

OUT

Noise Performance

= 5V

OUT

= 10µF

OUT

electrol

tic

1E+11E+21E+31E+4 1E+51E+6 1E+7

100

FREQUENCY (Hz)

100mA

10mA

1mA

10k 100k1M10M

Power Supply Ripple Rejection

vs. Voltage Drop

1mA

= 100mA

OUT

10mA

= 2.2µF

OUT

= 0.01µF

BYP

Noise Performance

100mA

OUT

electrolytic C

BYP

100

= 5V

= 10µF

= 100pF

1mA

10mA

10k 100k1M10M

Noise Performance

10mA, C

OUT

0.1

0.01

NOISE (µV/√Hz)

0.001 V

0.0001

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

100

FREQUENCY (Hz)

OUT

10k 100k 1M 10M

= 1µF

= 5V

Page 6

MIC5219 Micrel

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. Supply Voltage

GROUND CURRENT (mA)

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

MIC5219 6 July 2000

Page 7

MIC5219 Micrel

OUT

BYP

(optional)

GND

REF

Bandgap

Ref.

Current Limit

Thermal Shutdown

OUT

MIC5219-x.xBM5/MM

Block Diagrams

Ultra-Low-Noise Fixed Regulator

Bandgap

Ref.

REF

Current Limit

Thermal Shutdown

MIC5219BM5/MM [adj.]

GND

Ultra-Low-Noise Adjustable Regulator

OUT

BYP

(optional)

OUT

July 2000 7 MIC5219

Page 8

MIC5219 Micrel

P =

T – T

(max)

J(max) A

()

Applications Information

The MIC5219 is designed for 150mA to 200mA output current 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 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 5Ω 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.

is the maximum junction temperature of the die,

J(MAX)

125°C, and TA 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

θθ

θJA Recommended

θθ

Minimum Footprint 2 oz. 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

Substituting P

D(MAX)

) I

OUT

+ VIN I

GND

OUT

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

°°

P =

D(max)

()

C/W

°220

= 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 Characteristics 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

lators

handbook.

Designing with Low-Dropout Voltage Regu-

MIC5219 8 July 2000

Page 9

MIC5219 Micrel

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 (θ

= 220°C/W for

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

T – T

()

P =

(max)

J(max) A

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

125 C – 25 C

°°

P =

D(max)

()

C/W

°220

= 455mW

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

P I V I

= 455mW = (VIN – V

D(max)

= 500mA

OUT

= 5V

OUT

= 20mA

GND

OUT

) I

OUT

+ VIN I

GND

455mW = (VIN – 5V) 500mA + VIN × 20mA

2.995W = 520mA × V V

IN(max)

2.955W

520mA

5.683V

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 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 to that used in 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 =

 

DIN



455mW =

0.274 =

% Duty Cycle



V – V I V I



()



100

% DC

 





8V – 5V 500mA 8V 20mA

()





100

% Duty Cycle

 



100

OUT OUT



1.66W





GND

+×

% 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

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.

July 2000 9 MIC5219

Page 10

MIC5219 Micrel

400mA

VOLTAGE DROP (V)

0 20406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

VOLTAGE DROP (V)

400mA

0 20406080100

100mA

200mA

300mA

500mA

DUTY CYCLE (%)

VOLTAGE DROP (V)

0 20406080100

100mA

200mA

500mA

400mA

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

400mA

VOLTAGE DROP (V)

0 20406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

VOLTAGE DROP (V)

400mA

0 20406080100

DUTY CYCLE (%)

100mA

200mA

300mA

500mA

VOLTAGE DROP (V)

400mA

0 20406080100

100mA

500mA

DUTY CYCLE (%)

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

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

300mA

200mA

300mA

400mA

VOLTAGE DROP (V)

0 20406080100

500mA

DUTY CYCLE (%)

100mA

200mA

300mA

400mA

VOLTAGE DROP (V)

0 20406080100

100mA

200mA

300mA

500mA

DUTY CYCLE (%)

VOLTAGE DROP (V)

400mA

0 20406080100

100mA

500mA

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

VOLTAGE DROP (V)

0 20406080100

400mA

DUTY CYCLE (%)

200mA

300mA

500mA

400mA

VOLTAGE DROP (V)

0 20406080100

DUTY CYCLE (%)

200mA

300mA

500mA

400mA

VOLTAGE DROP (V)

0 20406080100

500mA

DUTY CYCLE (%)

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

MIC5219 10 July 2000

Page 11

MIC5219 Micrel

PD × 50mA = 0.875 × 173mW PD × 50mA = 151mW

The power dissipation at 500mA must also be calculated.

× 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.

P P P

= 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

Dropout Voltage Regulators

handbook.

Designing with Low-

Fixed Regulator Circuits

MIC5219-x.x

IN OUT EN BYP

GND

1µF

OUT

MIC5219-x.x

IN OUT EN BYP

GND

470pF

OUT

2.2µF

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 5. Low-Noise Fixed Voltage Regulator

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 8. Ultra-Low-Noise Adjustable Application.

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

July 2000 11 MIC5219

Page 12

MIC5219 Micrel

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)

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.

MIC5219 12 July 2000