MIC5238-1.3YD5TR - Micrel

MIC5238

Ultra-Low Quiescent Current, 150mA

µCap LDO Regulator

IttyBitty is a registered trademark of Micrel, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

General Description

The MIC5238 is an ultra-low voltage output, 150mA LDO

regulator. Designed to operate in a single supply or dual

supply mode, the MIC5238 consumes only 23µA of bias

current, improving efficiency. When operating in the dual

supply mode, the efficiency greatly improves as the higher

voltage supply is only required to supply the 23µA bias

current while the output and base drive comes off of the

much lower input supply voltage.

As a µCap regulator, the MIC5238 operates with a 2.2µF

ceramic capacitor on the output, offering a smaller overall

solution. It also incorporates a logic-level enable pin that

allows the MIC5238 to be put into a zero off-current mode

when disabled.

The MIC5238 is fully protected with current limit and

thermal shutdown. It is offered in the IttyBitty® SOT-23-5

package with an operating junction temperature range of

–40°C to +125°C.

Data sheets and support documentation can be found on

Micrel’s web site at: www.micrel.com.

Features

• Ultra-low input voltage range:1.5V to 6V

• Ultra-low output voltage:1.0V minimum output voltage

• Low dropout voltage: 310mV at 150mA

• High output accuracy: ±2.0% over temperature

• µCap: stable with ceramic or tantalum capacitors

• Excellent line and load regulation specifications

• Zero shutdown current

• Reverse leakage protection

• Thermal shutdown and current limit protection

• IttyBitty® SOT-23-5 package

Applications

• PDAs and pocket PCs

• Cellular phones

• Battery powered systems

• Low power microprocessor power supplies

___________________________________________________________________________________________________________

Typical Application

Ultra-Low Voltage Application

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Ordering Information

Part Number

Standard Marking Code Pb-Free Marking Code*

Voltage** Junction

Temp. Range Package

MIC5238-1.0BM5 L410 MIC5238-1.0YM5 L410 1.0V –40° to +125°C SOT-23-5

MIC5238-1.1BM5 L411 MIC5238-1.1YM5 L411 1.1V –40° to +125°C SOT-23-5

MIC5238-1.3BM5 L413 MIC5238-1.3YM5 L413 1.3V –40° to +125°C SOT-23-5

MIC5238-1.0BD5 N410 MIC5238-1.0YD5 N410 1.0V –40° to +125°C TSOT-23-5

MIC5238-1.1BD5 N411 MIC5238-1.1YD5 N411 1.1V –40° to +125°C TSOT-23-5

MIC5238-1.3BD5 N413 MIC5238-1.3YD5 N413 1.3V –40° to +125°C TSOT-23-5

Notes:

* Under bar symbol ( _ ) may not be to scale.

** Other voltage options available. Contact Micrel Marketing for details.

Pin Configur ation

5-Pin SOT-23 (M5) 5-Pin Thin SOT-23 (D5)

Pin Description

Pin Number Pin Name Pin Function

1 IN Supply Input

2 GND Ground

3 EN

Enable (Input): Logic Low = shutdown; Logic High = enable. Don not leave

open.

4 BIAS Bias Supply Input

5 OUT Regulator Output

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Absolute Maximum Ratings(1)

Input Supply Voltage (VIN)................................. –0.3V to 7V

BIAS Supply Voltage (VBIAS).............................. –0.3V to 7V

Enable Supply Voltage (VEN)............................. –0.3V to 7V

Power Dissipation (PD)..............................Internally Limited

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

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

ESD Rating(3)......................................................1.5µA HBM

Operating Ratings(2)

Supply Voltage (VIN)............................................ 1.5V to 6V

BIAS Supply Voltage (VBIAS)................................ 2.3V to 6V

Enable Supply Voltage (VEN).................................. 0V to 6V

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

Package Thermal Resistance

SOT-23-5 (θJA) .................................................235°C/W

Electrical Characteristics(4)

TA = 25°C with VIN = VOUT + 1V; VBIAS = 3.3V; IOUT = 100µA; VEN = 2V, bold values indicate –40°C < TJ < +125°C, unless

specified.

Parameter Condition Min Typ Max Units

Output Voltage Accuracy Variation from nominal VOUT –1.5

–2

+1.5

Line Regulation VBIAS = 2.3V to 6V, Note 5 0.25 0.5 %

Input Line Regulation VIN = (VOUT 1V) to 6V 0.04 4 %

Load Regulation Load = 100µA to 150mA 0.7 1 %

IOUT = 100µA 50 mV

IOUT = 50mA 230 300

400

IOUT = 100mA 270 mV

Dropout Voltage

IOUT = 150mA 310 450

500

BIAS Current, Note 6 IOUT = 100µA 23 µA

IOUT = 100µA 7 20 µA

IOUT = 50mA, Note 7 0.35 mA

IOUT = 100mA 1 mA

Input Current, Pin 1

IOUT = 150mA 2 2.5 mA

VEN ≤ 0.2V, VIN = 6V, VBIAS = 6V 1.5 5 µA Ground Current in Shutdown

VEN = 0V, VIN = 6V, VBIAS = 6V 0.5 µA

Short Circuit Current VOUT = 0V 350 500 mA

Reverse Leakage VIN = 0V, VEN = 0V, VOUT = nom VOUT 5 µA

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Electrical Characteristics(4) cont.

TA = 25°C with VIN = VOUT + 1V; VBIAS = 3.3V; IOUT = 100µA; VEN = 2V, bold values indicate –40°C < TJ < +125°C, unless

specified.

Parameter Condition Min Typ Max Units

Enable Input

Input Low Voltage Regulator OFF 0.2

Input High Voltage Regulator ON 2.0 V

VEN = 0.2V, Regulator OFF –1.0 0.01 1.0 µA Enable Input Current

VEN = 0.2V, Regulator ON 0.1 1.0 µA

Notes:

1. Exceeding the absolute maximum rating may damage the device.

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

3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

4. Specification for packaged product only.

5. Line regulation measures a change in output voltage due to a change in the bias voltage.

6. Current measured from bias input to ground.

7. Current differential between output current and main input current at rated load current.

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Typical Characteristics

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Typical Characteristics cont .

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Functional Characteristics

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Functional Diagram

Block Diagram – Fixed Ou tput Voltage

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Application Information

Enable/Shutdown

The MIC5238 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-

mode-current state. In this state, current consumed by the

regulator goes nearly to zero. Forcing the enable pin high

enables the output voltage.

Input Bias Capacitor

The input capacitor must be rated to sustain voltages that

may be used on the input. An input capacitor may be

required when the device is not near the source power

supply or when supplied by a battery. Small, surface

mount, ceramic capacitors can be used for bypassing.

Larger values may be required if the source supply has

high ripple.

Output Capacitor

The MIC5238 requires an output capacitor for stability. The

design requires 2.2µF or greater on the output to maintain

stability. The design is optimized for use with low-ESR

ceramic chip capacitors. High ESR capacitors may cause

high frequency oscillation. The maximum recommended

ESR is 3Ω. The output capacitor can be increased without

limit. Larger valued capacitors help to improve transient

response.

X7R/X5R dielectric-type ceramic capacitors are recom-

mended because of their temperature performance. X7R-

type capacitors change capacitance by 15% over their

operating temperature range and are the most stable type

of ceramic capacitors. Z5U and Y5V dielectric capacitors

change value by as much as 50% and 60% respectively

over their operating temperature ranges. To use a ceramic

chip capacitor with Y5V dielectric, the value must be much

higher than a X7R ceramic capacitor to ensure the same

minimum capacitance over the equivalent operating

temperature range.

No-Load Stability

The MIC5238 will remain stable and in regulation with no

load unlike many other voltage regulators. This is especially

important in CMOS RAM keep-alive applications.

Thermal Considerations

The MIC5238 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:

AJ(max)

D(MAX)

T - T

TJ(MAX) is the maximum junction temperature of the die,

125°C, and TA is the ambient operating temperature. θJA is

layout dependent; Table 1 shows the junction-to-ambient

thermal resistance for the MIC5238.

Package θJA Recommended

Minimum Footprint

SOT-23-5 235°C/W

Table 1. SOT-23-5 Thermal Resistance

The actual power dissipation of the regulator circuit can be

determined using the equation:

D = (VIN – VOUT) IOUT + VINIGND

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, when operating the MIC5238-1.0BM5 at 50°C

with a minimum footprint layout, the maximum input voltage

for a set output current can be determined as follows.

C/W235

C50 - C125

PD(MAX) °

°°

D(MAX) = 319mW

The junction-to-ambient (θJA) thermal resistance for the

minimum footprint is 235°C/W, from Table 1. It is important

that the maximum power dissipation not be exceeded to

ensure proper operation. With very high input-to-output

voltage differentials, the output current is limited by the total

power dissipation. Total power dissipation is calculated

using the following equation:

D = (VIN – VOUT) IOUT + VIN x IGND + VBIAS x IBIAS

Since the bias supply draws only 18µA, that contribution

can be ignored for this calculation.

If we know the maximum load current, we can solve for the

maximum input voltage using the maximum power dissipa-

tion calculated for a 50°C ambient, 319mV.

D(MAX) = (VIN – VOUT) IOUT + VIN x IGND

319mW = (VIN – 1V) 150mA + VIN x 2.8mA

Ground pin current is estimated using the typical

characteristics of the device.

469mW = VIN (152.8mA)

IN = 3.07V

For higher current outputs only a lower input voltage will

work for higher ambient temperatures.

Assuming a lower output current of 20mA, the maximum

input voltage can be recalculated:

319mW = (VIN – 1V) 20mA + VIN x 0.2mA

339mW = VIN x 20.2mA

IN = 16.8V

Maximum input voltage for a 20mA load current at 50°C

ambient temperature is 16.8V. Since the device has a 6V

rating, it will operate over the whole input range.

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Dual Supply Mode Efficiency

By utilizing a bias supply the conversion efficiency can be

greatly enhanced. This can be realized as the higher bias

supply will only consume a few µA’s while the input supply

will require a few mA’s. This equates to higher efficiency

saving valuable power in the system. As an example,

consider an output voltage of 1V with an input supply of

2.5V at a load current of 150mA. The input ground current

under these conditions is 2mA, while the bias current is

only 20µA. If we calculate the conversion efficiency using

the single supply approach, it is as follows:

Input power = VIN × output current + VIN × (VBIAS ground

current + VIN ground current)

Input power = 2.5V × 150mA + 2.5 × (0.0002+0.002) =

380.5mW

Output power = 1V × 0.15 = 150mW

Efficiency = 150/380.5 × 100 = 39.4%

Now, using a lower input supply of 1.5V, and powering the

bias voltage only from the 2.5V input, the efficiency is as

follows:

Input power = VIN × output current + VIN × VIN ground

current + VBIAS x VBIAS ground current

Input power = 1.5 × 150mA + 1.5 × 0.002 + 2.5 × 0.0002 =

225mW

Output power = 1V × 150mA = 150mW

Efficiency = 150/225 × 100 = 66.6 %

Therefore, by using the dual supply MIC5238 LDO the

efficiency is nearly doubled over the single supply version.

This is a valuable asset in portable power management

applications equating to longer battery life and less heat

being generated in the application.

This in turn will allow a smaller footprint design and an

extended operating life.

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Package Information

5-Pin SOT-23 (M5)

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Package Information cont.

5-Pin Thin SOT-23 (D5)

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

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

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical impla

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

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