Datasheet MIC5247-1.8BM5, MIC5247-2.0BM5, MIC5247-2.4BM5, MIC5247-1.5BM5 Datasheet (MICREL)

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MIC5247 Micrel

MIC5247

150mA Low-Voltage µCap Linear Regulator

Preliminary Information

General Description

The MIC5247 is an efficient, precise low voltage CMOS voltage regulator optimized for ultra-low-noise applications. The MIC5247 offers better than 1% initial accuracy, and 85µA constant ground current over load (typically 85µA). The MIC5247 provides a very low noise output, ideal for RF applications where quiet voltage sources are required. A noise bypass pin is also available for further reduction of output noise.

Designed specifically for hand-held and battery-powered devices, the MIC5247 provides a logic compatible enable pin. When disabled, power consumption drops nearly to zero.

The MIC5247 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices.

Key features include current limit, thermal shutdown, a pushpull output for faster transient response, and an active clamp to speed up device turnoff. Available in the IttyBitty™ SOT-23-5 package, the MIC5247 also offers a range of fixed output voltages.

Features

• Ultralow noise

• Low voltage outputs

• Load independent, ultralow ground current: 85µA

• 150mA output current

• Current limiting

• Thermal Shutdown

• Tight load and line regulation

•“Zero” off-mode current

• Stability with low-ESR capacitors

• Fast transient response

• Logic-controlled enable input

Applications

• Cellular phones and pagers

• Cellular accessories

• Battery-powered equipment

• Laptop, notebook, and palmtop computers

• PCMCIA VCC and VPP regulation/switching

• Consumer/personal electronics

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

• High-efficiency linear power supplies

Typical Application

Ordering Information

Part Number Marking Voltage Junction Temp. Range Package

MIC5247-1.5BM5 LU15 1.5V –40°C to +125°C SOT-23-5 MIC5247-1.8BM5 LU18 1.8V –40°C to +125°C SOT-23-5 MIC5247-2.0BM5 LU20 2.0V –40°C to +125°C SOT-23-5 MIC5247-2.4BM5 LU24 2.4V –40°C to +125°C SOT-23-5

Other voltages available. Contact Micrel for details.

MIC5247-x.xBM5

15 2

Enable

Shutdown

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

Ultra-Low-Noise Regulator Application

OUT

BYP

(optional)

IttyBitty is a trademark of Micrel, Inc.

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

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MIC5247 Micrel

Pin Configuration

Pin Description

Pin Number Pin Name Pin Function

1 IN Supply Input 2 GND Ground 3 EN Enable/Shutdown (Input): CMOS compatible input. Logic high = enable;

4 BYP Reference Bypass: Connect external 0.01pF capacitor to GND to reduce

5 OUT Regulator Output

GND

LUxx

OUTBYP

MIC5247-x.xBM5

logic low = shutdown. Do not leave open.

output noise. May be left open.

Absolute Maximum Ratings (Note 1)

Supply Input Voltage (VIN) .................................. 0V to +7V

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

Junction Temperature (TJ) ...................................... +150°C

Storage Temperature ............................... –65°C to +150°C

Operating Ratings (Note 2)

Input Voltage (VIN) ......................................... +2.7V to +6V

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

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

Thermal Resistance (θJA)......................................235°C/W

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

ESD, Note 3

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MIC5247 Micrel

Electrical Characteristics

VIN = V

Symbol Parameter Conditions Min Typical Max Units

∆V

LNR

∆V

LDR

VIN – V I

GND

PSRR Power Supply Rejection f ≤ 1kHz 50 dB I

LIM

Enable Input

Thermal Protection

+ 1.0V; VIN = VEN; I

OUT

Output Voltage Accuracy I

Line Regulation VIN = V Load Regulation I Load Regulation for 1.5V only I

OUT

Dropout Voltage I Quiescent Current V Ground Pin Current, Note 6 I

Current Limit V Output Voltage Noise C

Enable Input Logic-Low Voltage VIN = 2.7V to 5.5V, regulator shutdown 0.8 0.4 V Enable Input Logic-High Voltage VIN = 2.7V to 5.5V, regulator enabled 1.6 1V Enable Input Current VIL ≤ 0.4V 0.01 µA

Shutdown Resistance Discharge 500 Ω

Thermal Shutdown Temperature 150 °C Thermal Shutdown Hysteresis 10 °C

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

OUT

= 0mA –11%

OUT

–22%

+ 0.1V to 6V –0.3 +0.3 %/V

OUT

= 0.1mA to 150mA, Note 4 23%

OUT

= 0.1mA to 150mA, V

OUT

= 150mA (see Note 5) 150 mV

OUT

≤ 0.4V (shutdown) 0.2 1 µA

= 0mA 85 150 µA

OUT

= 150mA 85 150 µA

OUT

= 0V 160 300 mA

OUT

= 10µF, C

OUT

f = 10Hz to 100kHz

= 0.01µF, 30 µVrms

BYP

= 1.5V 3 4 %

OUT

VIH ≥ 1.6V 0.01 µA

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. Devices are ESD sensitive. Handling precautions recommended. Note 4. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load

Note 5. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured a1V

Note 6. Ground pin current is the regulator quiescent current plus pass transistor base current. The total current drawn from the supply is the sum of

range from 0.1mA to 150mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.

differential. For outputs below 2.7V, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7V. Minimum input operating voltage is 2.7V.

the load current plus the ground pin current.

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MIC5247 Micrel

)

1x1011x1021x1031x1041x1051x10

PSRR (dB)

FREQUENCY (Hz)

Power Supply Rejection Ratio

BYP

= 0

0.01µF

1µF

IL = 100mA V

= 3.4V

OUT

= 2.4V

OUT

= 10µF Ceramic

100

01234

GROUND CURRENT (µA)

INPUT VOLTAGE (V)

Ground Pin Current

LOAD

= 100µA

100

200

300

400

500

-40 -10 20 50 80 110 140

SHORT CIRCUIT CURRENT (mA)

TEMPERATURE (°C)

Short Circuit Current

vs. Temperature

VOUT = 0

)

1x10

-1

1x1001x1011x1021x10

GROUND CURRENT (µA)

OUTPUT CURRENT (mA)

Ground Current

vs. Output Current

VIN = V

OUT

+ 1

Typical Characteristics

Power Supply Rejection Ratio

= 1µF

BYP

= 0.01µF

70 60

= 0

BYP

50 40

PSRR (dB)

30 20 10

IL = 100µA V

= 3.4V

= 2.4V

OUT

= 10µF Ceramic

OUT

1x1011x1021x1031x1041x1051x10

FREQUENCY (Hz)

Power Supply Rejection Ratio

0.01µF

1µF

PSRR (dB)

IL= 150mA

= 3.4V

OUT

1x1011x1021x1031x1041x1051x10

= 0

BYP

= 2.4V

= 10µF Ceramic

FREQUENCY (Hz

Power Supply Rejection Ratio

1µF

60 50

0.01µF

PSRR (dB)

IL = 50mA

= 3.4V

= 2.4V

OUT

=10µF Ceramic

OUT

1x1011x1021x1031x1041x1051x10

= 0

BYP

FREQUENCY (Hz

Noise Performance

-5

1x10

= 0

BYP

-6

1x10

= 0.01µF

BYP

-7

1x10

VIN = 2.8V

= 1.8V

OUT

= 4.7µF

OUT

-8

1x10

1x1011x1021x1031x1041x1051x10

OUTPUT SPECTRAL NOISE DENSITY (µV/rt Hz)

FREQUENCY (Hz

LOAD

= 50mA

Ground Pin Current

100

GROUND CURRENT (µA)

= 100µA

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

Ground Pin Current

100

MIC5247 4 November 6, 2000

GROUND CURRENT (µA)

01234

INPUT VOLTAGE (V)

LOAD

= 150mA

Ground Pin Current

100

GROUND CURRENT (µA)

= 150mA

LOAD

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

Dropout Characteristics

= 100µA

LOAD

VOLTAGE OUT (V)

01234

INPUT VOLTAGE (V)

LOAD

150mA

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MIC5247 Micrel

)

Output Voltage

vs. Temperature

2.5

2.4

OUTPUT VOLTAGE (V)

= 100µA

LOAD

2.3

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

Turn-On Time

vs. Bypass Capacitance

200

150

100

Rise Time

TIME (µs)

Prop Delay

1x10-51x10-41x10-31x10-21x10

BYPASS CAPACITOR (µF

C I

LOAD

OUT

= 10µF = 100mA

-1

1x1001x10

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Functional Characteristics

(100mV/div.)

OUTPUT VOL TA GE

(100mA/div.)

OUTPUT CURRENT

Load Transient Response

TIME (100µs/div.)

OUT

BYP

OUT

100mA

= 10µF = 0

= 3.4V

= 2.4V

100µA

Line Transient Response

4.4V

(1V/div.)

INPUT VOL TA GE

(50mV/div.)

OUTPUT VOL TA GE

3.4V

TIME (500µs/div.)

C V I

LOAD

OUT

= 10µF = 2.4V = 100µA

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MIC5247 Micrel

Block Diagrams

GND

Reference

Voltage

Thermal

Sensor

Under-

voltage

Lockout

Startup/

Shutdown

Control

FAULT

Quickstart/

Cancellation

Error

Amplifier

ACTIVE SHUTDOWN

Noise

Current

Amplifier

PULL

DOWN

BYP

OUT

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MIC5247 Micrel

D(max)

J(max) A

−

 



 



Applications Information

Enable/Shutdown

The MIC5247 comes with an active-high enable pin that allows the regulator to be disabled. Forcing the enable pin low disables the regulator and sends it into a “zero” off-modecurrent state. In this state, current consumed by the regulator goes nearly to zero. Forcing the enable pin high enables the output voltage. This part is CMOS and the enable pin cannot be left floating; a floating enable pin may cause an indeterminate state on the output.

Input Capacitor

An input capacitor is not required for stability. A 1µF input capacitor is recommended when the bulk ac supply capacitance is more than 10 inches away from the device, or when the supply is a battery.

Output Capacitor

The MIC5247 requires an output capacitor for stability. The design requires 1µF or greater on the output to maintain stability. The capacitor can be a low-ESR ceramic chip capacitor. The MIC5247 has been designed to work specifically with the low-cost, small chip capacitors. Tantalum capacitors can also be used for improved capacitance over temperature. The value of the capacitor can be increased without bound.

Bypass Capacitor

A capacitor can be placed from the noise bypass pin to ground to reduce output voltage noise. The capacitor bypasses the internal reference. A 0.01µF capacitor is recommended for applications that require low-noise outputs.

The bypass capacitor can be increased without bound, further reducing noise and improving PSRR. Turn-on time remains constant with respect to bypass capacitance. Refer to the Typical Characteristics section for a graph of turn-on time vs. bypass capacitor.

Transient Response

The MIC5247 implements a unique output stage to dramatically improve transient response recovery time. The output is a totem-pole configuration with a P-channel MOSFET pass device and an N-channel MOSFET clamp. The N-channel clamp is a significantly smaller device that prevents the output voltage from overshooting when a heavy load is removed. This feature helps to speed up the transient response by significantly decreasing transient response recovery time during the transition from heavy load (100mA) to light load (85µA).

Active Shutdown

The MIC5247 also features an active shutdown clamp, which is an N-channel MOSFET that turns on when the device is disabled. This allows the output capacitor and load to discharge, de-energizing the load.

Thermal Considerations

The MIC5247 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 thermal resistance 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 junction-toambient thermal resistance for the MIC5247.

Package θJA Recommended θJA 1" Square θ

Minimum Footprint Copper Clad

SOT-23-5 (M5) 235°C/W 185°C/W 145°C/W

Table 1. SOT-23-5 Thermal Resistance

The actual power dissipation of the regulator circuit can be determined using the 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, when operating the MIC5247-2.4BM5 at room temperature with a minimum footprint layout, the maximum input voltage for a set output current can be determined as follows:

D(max)



125 C 25 C

°− °



235 C/W



= 425mW

 



The junction-to-ambient thermal resistance for the minimum footprint is 235°C/W, from Table 1. The maximum power dissipation must not be exceeded for proper operation. Using the output voltage of 2.4V and an output current of 150mA, the maximum input voltage can be determined. Because this device is CMOS and the ground current is typically 100µA over the load range, the power dissipation contributed by the ground current is < 1% and can be ignored for this calculation.

425mW = (VIN – 2.4V) 150mA 425mW = VIN·150mA – 360mW 785mW = VIN·150mA V

IN(max)

= 5.2V

Therefore, a 2.4V application at 150mA of output current can accept a maximum input voltage of 5.2V 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-

Fixed Regulator Applications

MIC5247-x.xBM5

15 2 3

OUT

1µF

0.01µF

Figure 1. Ultra-Low-Noise Fixed Voltage Application

MIC5247 8 November 6, 2000

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MIC5247 Micrel

Figure 1 includes a 0.01µF capacitor for low-noise operation and shows EN (pin 3) connected to IN (pin 1) for an application where enable/shutdown is not required. C

OUT

= 1µF

minimum.

Enable

Shutdown

MIC5247-x.xBM5

15 2 34

OUT

1.0µF

Figure 2. Low-Noise Fixed Voltage Application

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

is not required. C

BYP

= 1µF minimum.

OUT

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MIC5247 Micrel

Package Information

1.90 (0.075) REF

0.95 (0.037) REF

3.02 (0.119)

2.80 (0.110)

0.50 (0.020)

0.35 (0.014)

1.75 (0.069)

1.50 (0.059)

1.30 (0.051)

0.90 (0.035)

0.15 (0.006)

0.00 (0.000)

SOT-23-5 (M)

3.00 (0.118)

2.60 (0.102)

10°

0°

DIMENSIONS:

MM (INCH)

0.20 (0.008)

0.09 (0.004)

0.60 (0.024)

0.10 (0.004)

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.

MIC5247 10 November 6, 2000