Datasheet MIC5231-5.0BM5, MIC5231-2.75BM5, MIC5231-3.0BM5, MIC5231-3.3BM5 Datasheet (MICREL)

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MIC5231 Micrel

MIC5231

Micropower µCap LDO Regulator

Preliminary Information

General Description

The MIC5231 µCap low-dropout voltage regulator is intended for low-output-current biasing applications. It features extremely low ground current, not greater than 4µA under all load and temperature conditions, making it efficient and ideal for keep-alive applications in devices such as notebook computers.

The MIC5231 offers better than 2% initial accuracy and low dropout (typically 150mV at 10mA output current). An output capacitor is not required for stable operation, decreasing cost and board space. Tiny ceramic chip capacitors may be used to improve transient response.

The MIC5231 also features a control pin which allows the regulator to be shut down when not required. Its shutdownstate draws zero current, benefitting battery-powered applications.

The MIC5231 is available in fixed output voltages of 2.75V,

3.0V, 3.3V and 5V in the small SOT-23-5 IttyBitty™ package. Contact Micrel for other voltage options.

Features

• Extremely low quiescent current—

• No output capacitor requirement

• Stable with ceramic or tantalum capacitors

• IttyBitty™ SOT-23-5 surface-mount package

• 10mA output drive

• Low 150mV at 10mA dropout voltage

• Tight load and line regulation

• Low temperature coefficient

• Logic-level enable input

only 0.65µA

Applications

• Real time clocks

• SRAM backup

• Cellular telephones

• Laptop, notebook and palmtop computers

• Battery-powered equipment

• Bar code scanners

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

Typical Application

Ordering Information

Part Number Marking Voltage Temperature Range Package

MIC5231-2.75BM5 LM2H 2.75V –40°C to +125°C SOT-23-5

MIC5231-3.0BM5 LM30 3.0V –40°C to +125°C SOT-23-5

MIC5231-3.3BM5 LM33 3.3V –40°C to +125°C SOT-23-5

MIC5231-5.0BM5 LM50 5.0V –40°C to +125°C SOT-23-5

5V Linear Regulator Application

MIC5231-5.0BM5

OUT

GND

V 5V

OUT

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

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MIC5231 Micrel

Pin Configuration

Pin Description

Pin Number Pin Name Pin Function

1 EN Enable (Input): Active high. Logic high = enable; logic low = shutdown. Do

2 GND Ground

3 IN Supply Input

4 OUT Regulated Output

5 NC not internally connected

GND

LM50

NCOUT

MIC5231-5.0BM5

not float.

Part Identification

Absolute Maximum Ratings (Note 1)

Supply Voltage (VIN) .................................... –0.6V to +14V

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

Storage Temperature (TA) ....................... –60°C to +150°C

ESD, Note 3 .................................................................. 2kV

Operating Ratings (Note 2)

Input Voltage (VIN) ........................................... 3.5V to 12V

Ambient Temperature (TA) ......................... –40°C to +85°C

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

Thermal Resistance, Note 4

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MIC5231 Micrel

Electrical Characteristics

VIN = V

Symbol Parameter Conditions Min Typ Max Units

OUT

∆V

OUT

∆V

OUT/VOUT

∆V

OUT/VOUT

PSRR Ripple Rejection f = 100Hz, IL = 100µA50dB

Enable Input

ENL

ENH

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: The maximum allowable power dissipation at any TA (ambient temperature) is P

Note 5: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.

Note 6: Regulation is measured at constant junction temperature using low duty cycle pulse testing.

Note 7: Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V

+ 1V; IL = 100µA; CL = 0.47µF; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted.

OUT

Output Voltage Accuracy variation from nominal V

OUT

–2+2% –3 +3 %

/∆T Output Voltage Note 5 250 ppm/°C

Temperature Coefficient

Line Regulation VIN = 6V to 12V 0.2 0.25 %

Load Regulation IL = 10µA to 10mA, Note 6 0.2 1 %

Dropout Voltage, Note 7 IL = 1mA 15 mV

IL = 10mA 150 300 mV

Ground Pin Current VIN = 6V, IL = 10mA 0.65 3 µA

VIN = 12V, IL = 10mA 1.1 4 µA

Enable Input Voltage VEN = logic low (regulator off) 0.4 0.18 V

VEN = logic high ((regulator on) 1.4 V

Enable Input Current V

130°C/W. Mounted to a standard PC board, the θJA is approximately 235°C/W.

differential. For outputs below 3.5V, dropout voltage is the input-to-output differential with the minimum input voltage 3.5V. Minimum input operating voltage is 3.5V.

≤ 0.18V (regulator off) 1 nA

ENL

≥ 1.4V (regulator on) 1 nA

ENH

D(max)

= (T

– TA) ÷ θJA. The θJC of the MIC5231 is

J(max)

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Ground Current

vs. Output Current

0.5

GROUND CURRENT (µA)

0110

OUTPUT CURRENT (mA)

Ground Current

3.10

3.05

3.00

2.95

OUTPUT VOLTAGE (V)

2.90

vs. Temperature

-50 -20 10 40 70 100 130

TEMPERATURE (°C)

Ground Current

vs. Supply Volta

0.8

0.7

0.6

0.5

0.4

Ground Current (µA)

0.3

0.2 24681012

Supply Voltage (V)

0.8

0.6

0.4

0.2

GROUND CURRENT (µA)

-40 0 40 80 120

Short Circuit Current

150

100

SHORT CIRCUIT CURRENT (mA)

vs. Temperature

-50 -20 10 40 70 100 130

TEMPERATURE (°C)

Ground Current

vs. Temperature

TEMPERATURE (°C)

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MIC5231 Micrel

Block Diagram

IN OUT

MIC5231

GND

Applications Information

Input Capacitor

A 0.1µF (or larger) capacitor should be placed from the IN (supply input) to GND (ground) if there is more than 20 cm of wire between IN and the ac filter capacitor or if supplied from a battery.

Output Capacitors

The MIC5231 does not require an output capacitor for stability. A 1µF or larger capacitor is recommended between OUT (output) and GND to improve the regulator’s transient response. A 0.1µF capacitor can be used to reduce overshoot recovery time at the expense of overshoot amplitude. The ESR (effective series resistance) of this capacitor has no effect on regulator stability, but low-ESR capacitors improve high frequency transient response. The value of this capacitor may be increased without limit, but values larger than 10µF tend to increase the settling time after a step change in input voltage or output current.

The MIC5231 has no minimum load current; it will remain stable and in regulation with no load (other than the internal voltage divider). This is especially important in real-time clock and CMOS RAM keep-alive applications.

Minimum Load Current

The MIC5231 does not require a minimum load for proper operation. This allows the device to operate in applications where very light output currents are required for keep-alive purposes. This is important for powering SRAM or Flash memory in low-power modes for handheld devices.

Bandgap

Reference

Safe Operating Conditions

The MIC5231 does not incorporate current limit or thermal shutdown in the design. The output pass element is approximately 15 ohms, therefore, when a short occurs from the output to ground, the current is self-limited. The pass element has a positive temperature coefficient, such that when the device gets hot, the output impedance goes up, limiting the current even further. The maximum junction temperature for the device is 125°C, and it is important that this is not exceeded for any length of time.

Thermal Considerations

The MIC5231 is not intended for sourcing currents that would cause a large power loss in the device, but since it is not current limited, it is possible to source more than the rated 10mA. At this point, it is important to ensure that the die temperature does not exceed 125°C.

Power dissipation in the regulator is calculated as follows:

PD = (VIN – V

OUT

)*I

OUT

+ VIN *I

GND

The MIC5231 consumes only 0.65uA over load and does not need to consider that contribution in the power dissipation equation, therefore the equation is simplified.

PD = (VIN – V

OUT

)*I

OUT

The MIC5231, in the IttyBitty SOT23-5 package, has a thermal resistance, junction-to-ambient, of 235°C/W. Using this number, the power dissipation capability of that package, without exceeding a 125°C junction temperature rating, can easily be calculated.

= (T

D(max)

= (125°C – Ta)/235°C/W

D(max)

j(max)

– Ta)/θ

If the device is being operated at 85°C, the maximum power

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dissipation allowed can easily be determined.

= (125°C – 85°C)/235°C/W

D(max)

= 170mW

D(max)

Therefore, the device can only dissipate 170mW maximum. If the MIC5231 is powered off of a 12V source and the output voltage is 3.3V, the maximum output current can be calculated.

PD = (Vin - Vout)·Iout

170mW = (12V - 3.3V)·Iout

Iout = 170mW/8.7V

Iout = 19.5mA

Therefore, the device can source almost 20mA at an ambient of 85°C before the die temperature exceeds 125°C.

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MIC5231 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)

3.00 (0.118)

2.60 (0.102)

SOT-23-5 (M5)

10°

0°

DIMENSIONS:

MM (INCH)

0.60 (0.024)

0.10 (0.004)

0.20 (0.008)

0.09 (0.004)

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MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970

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.

MIC5231 8 June 2000