MIC5256-1.8BM5 - Micrel, Inc.

MIC5256

150mA µCap LDO with Error Flag

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 MIC5256 is an efficient, precise CMOS voltage

regulator. It offers better than 1% initial accuracy,

extremely low-dropout voltage (typically 135mV at 150mA)

and low ground current (typically 90µA) over load. The

MIC5256 features an error flag that indicates an output

fault condition such as overcurrent, thermal shutdown and

dropout.

Designed specifically for handheld and battery-powered

devices, the MIC5256 provides a TTL-logic-compatible

enable pin. When disabled, power consumption drops

nearly to zero.

The MIC5256 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, faster

transient response, and an active clamp to speed up

device turnoff. Available in the IttyBitty® SOT-23-5

package and the new Thin SOT-23-5, which offers the

same footprint as the standard IttyBitty® SOT-23-5, but

only 1mm tall. The MIC5256 offers a range of output

voltages.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Features

• Input voltage range: 2.7V to 6.0V

• Thin SOT package: 1mm height

• Error flag indicates fault condition

• Stable with ceramic output capacitor

• Ultralow dropout: 135mV @ 150mA

• High output accuracy:

– 1.0% initial accuracy

– 2.0% over temperature

• Low quiescent current:90µA

• Tight load and line regulation

• Thermal-shutdown and current-limit protection

• “Zero” off-mode current

• TTL logic-controlled enable input

Applications

• Cellular phones and pagers

• Cellular accessories

• Battery-powered equipment

• Laptop, notebook, and palmtop computers

• Consumer/personal electronics

___________________________________________________________________________________________________________

Typical Application

Low-Noise Regulator Application

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Ordering Information

Part Number Marking

Standard Pb-Free Standard Pb-Free*

Voltage** Junction Temperature

Range Package

MIC5256-1.5BM5 MIC5256-1.5YM5 LX15 LX15 1.5V –40° to +125°C 5-Pin SOT23

MIC5256-1.8BM5 MIC5256-1.8YM5 LX18 LX18 1.8V –40° to +125°C 5-Pin SOT23

MIC5256-2.5BM5 MIC5256-2.5YM5 LX25 LX25 2.5V –40° to +125°C 5-Pin SOT23

MIC5256-2.6BM5 MIC5256-2.6YM5 LX26 LX26 2.6V –40° to +125°C 5-Pin SOT23

MIC5256-2.7BM5 MIC5256-2.7YM5 LX27 LX27 2.7V –40° to +125°C 5-Pin SOT23

MIC5256-2.8BM5 MIC5256-2.8YM5 LX28 LX28 2.8V –40° to +125°C 5-Pin SOT23

MIC5256-2.85BM5 MIC5256-2.85YM5 LX2J LX2J 2.85V –40° to +125°C 5-Pin SOT23

MIC5256-2.9BM5 MIC5256-2.9YM5 LX29 LX29 2.9V –40° to +125°C 5-Pin SOT23

MIC5256-3.0BM5 MIC5256-3.0YM5 LX30 LX30 3.0V –40° to +125°C 5-Pin SOT23

MIC5256-3.1BM5 MIC5256-3.1YM5 LX31 LX31 3.1V –40° to +125°C 5-Pin SOT23

MIC5256-3.3BM5 MIC5256-3.3YM5 LX33 LX33 3.3V –40° to +125°C 5-Pin SOT23

MIC5256-2.85BD5 MIC5256-2.85YD5 NX2J NX2J 2.85V –40° to +125°C 5-Pin TSOT23

Notes:

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

** Other Voltage available. Contact Micrel for details.

Pin Configur ation

MIC5256-x.xBM5

5-Pin SOT23

MIC5256-x.xBD5

5-Pin Thin SOT23

MIC5256-x.xYM5

5-Pin SOT23

MIC5256-x.xYD5

5-Pin Thin SOT23

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Pin Description

Pin Number Pin Name Pin Name

1 IN Supply Input.

2 GND Ground.

3 EN

Enable/Shutdown (Input): CMOS compatible input. Logic high = enable; logic low = shutdown. Do not

leave open.

4 FLG Error Flag (Output): Open-drain output. Active low indicates an output undervoltage condition.

5 OUT Regulator Output.

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Absolute Maximum Ratings(1)

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

Enable Voltage (VEN)............................................ 0V to +7V

Power Dissipation (PD)........................... Internally Limited(3)

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

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

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

EDS Rating(4).................................................................. 2kV

Operating Ratings(2)

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

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

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

Thermal Resistance

SOT23-5 (θJA) ..................................................235°C/W

Electrical Characteristics(5)

VIN = VOUT + 1V, VEN = VIN; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C  TJ  +125°C; unless noted.

Symbol Parameter Condition Min. Typ. Max. Units

VO Output Voltage Accuracy IOUT = 100µA –1

–2

VLNR Line Regulation VIN = VOUT + 1V to 6V 0.02 0.05 %/V

VLDR Load Regulation IOUT = 0.1mA to 150mA(6) 1.5 2.5 %

IOUT = 100µA 0.1 5 mV

IOUT = 100mA 90 150 mV

VIN –

VOUT Dropout Voltage(7)

IOUT = 150mA 135 200

250

IQ Quiescent Current VEN  0.4V (shutdown) 0.2 1 µA

IOUT = 0mA 90 150 µA

IGND Ground Pin Current(8) IOUT = 150mA 117 µA

f = 10Hz, VIN = VOUT + 1V; COUT = 1.0µF 60 dB

f = 100Hz, VIN = VOUT + 0.5V; COUT =

1.0µF

60 dB

PSRR Ripple Rejection

f = 10kHz, VIN = VOUT + 0.5V 45 dB

ILIM Current Limit VOUT = 0V 160 425 mV

en Output Voltage Noise TBD µV(rms)

Enable Input

VIL Enable Input Logic-Low Voltage VIN = 2.7V to 5.5V, regulator shutdown 0.4 V

VIH Enable Input Logic-High

Voltage

VIN = 2.7V to 5.5V, regulator enabled 1.6 V

VIL  0.4V, regulator shutdown 0.01 µA

IEN Enable Input Current VIH  1.6V, regulator enabled 0.01 µA

Shutdown Resistance

Discharge

500 

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Electrical Characteristics(5) (Continued)

VIN = VOUT + 1V, VEN = VIN; IOUT = 100µA; TJ = 25°C, bold values indicate –40°C  TJ  +125°C; unless noted.

Symbol Parameter Condition Min. Typ. Max. Units

Error Flag

VFLG Low Threshold

High Threshold

% of VOUT (Flag ON)

% of VOUT (Flag OFF)

VOL Output Logic-Low Voltage IL = 100µA, fault condition 0.02 0.1 V

IFL Flag Leakage Current flag off, VFLG = 6V 0.01 µA

Thermal Protection

Thermal-Shutdown

Temperature 150 °C

Thermal-Shutdown Hysteresis 10 °C

Notes:

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

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

3. The maximum allowable power dissipation of any TA (ambient temperature) is PD(max) = TJ(max)–TA / JA. Exceeding the maximum allowable power

dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The JA of the MIC5255-x.xBM5 (all versions) is

235°C/W on a PC board (see “Thermal Considerations” section for further details).

4. Devices are ESD sensitive. Handling precautions recommended.

5. Specification for packaged product only.

6. Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested for load regulation in the load range from

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

7. Dropout Voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1Vdifferential.

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.

8. Ground pin current is the regulator quiescent current. The total current drawn from the supply is the sum of the load current plus the ground pin

current.

Test Circuit

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Typical Characteristics

100

105

110

115

120

125

130

0.1 1 10 100 1000

(TNERRUCDNUORGµ)A

OUTPUT CURRENT (mA)

Ground Pin Current

VIN = VOUT + 1V

100

120

140

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

(TNERRUCDNUORGµ)A

INPUT VOLTAGE (V)

Ground Pin Current

ILOAD = 150mA

0.5

1.5

2.5

3.5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

)V(EGATLOVTUPTUO

INPUT VOLTAGE (V)

Dropout Characteristics

ILOAD = 150mA

ILOAD = 100µA

100

120

140

160

180

-40 -20 0 20 40 60 80 100120140

)Vm(EGATLOVTUOPORD

TEMPERATURE (°C)

Dropout Voltage

ILOAD = 150mA

100

120

140

160

180

0 20 40 60 80 100 120 140 160

)Vm(EGATLOVTUOPORD

OUTPUT CURRENT (mA)

Dropout Voltage

T = –40C

T = 25C T = 125C

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Typical Characteristics (Continued)

100

200

300

400

500

600

3 3.5 4 4.5 5 5.5 6

)Am(TNERRUCTIUCRICTROHS

INPUT VOLTAGE (V)

Short Circuit Current

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Functional Characteristics

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Functional Diagram

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Application Information

Enable/Shutdown

The MIC5256 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. 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

The MIC5256 is a high-performance, high-bandwidth

device. Therefore, it requires a well-bypassed input

supply for optimal performance. A 1µF capacitor is

required from the input to ground to provide stability.

Low-ESR ceramic capacitors provide optimal

performance at a minimum of space. Additional high-

frequency capacitors, such as small valued NPO

dielectric type capacitors, help filter out high frequency

noise and are good practice in any RF based circuit.

Output capacitor

The MIC5256 requires an output capacitor for stability.

The design requires 1µF 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 300m. The output capacitor can

be increased, but performance has been optimized for a

1µF ceramic output capacitor and does not improve

significantly with larger capacitance.

X7R/X5R dielectric-type ceramic capacitors are

recommended 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

an X7R ceramic capacitor to ensure the same minimum

capacitance over the equivalent operating temperature

range.

Error Flag

The error flag output is an active-low, open-drain output

that drives low when a fault condition AND an under-

voltage detection occurs. Internal circuitry intelligently

monitors overcurrent, overtemperature and dropout

conditions and ORs these outputs together to indicate

some fault condition. The output of that OR gate is

ANDed with an output voltage monitor that detects an

undervoltage condition. That output drives the open-

drain transistor to indicate a fault. This prevents

chattering or inadvertent triggering of the error flag. The

error flag must be pulled-up using a resistor from the flag

pin to either the input or the output.

The error flag circuit was designed essentially to work

with a capacitor to ground to act as a power-on reset

generator, signaling a power-good situation once the

regulated voltage was up and/or out of a fault condition.

This capacitor delays the error signal from pulling high,

allowing the down stream circuits time to stabilize. When

the error flag is pulled-up to the input without using a

pull-down capacitor, then there can be a glitch on the

error flag upon start up of the device. This is due to the

response time of the error flag circuit as the device starts

up. When the device comes out of the “zero” off mode

current state, all the various nodes of the circuit power

up before the device begins supplying full current to the

output capacitor. The error flag drives low immediately

and then releases after a few microseconds. The

intelligent circuit that triggers an error detects the output

going into current limit AND the output being low while

charging the output capacitor. The error output then pulls

low for the duration of the turn-on time. A capacitor from

the error flag to ground will filter out this glitch. The glitch

does not occur if the error flag pulled up to the output.

Active Shutdown

The MIC5256 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.

No Load Stability

The MIC5256 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 MIC5256 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) 

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

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

is layout dependent; Table 1 shows examples of

junction-to-ambient thermal resistance for the MIC5256.

Package θJA Recommen ded

Minimum Footprint θJA 1” Square

Copper Clad θJC

SOT23-5

(M5 or D5) 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:

D = (VIN – VOUT) IOUT + VIN IGND

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 MIC5256-3.0BM5 at

50°C with a minimum footprint layout, the maximum

input voltage for a set output current can be determined

as follows:

⎟

⎠

⎞

⎜

⎝

⎛

°−°

=C/W235

C50C125

PD(max)

D(max) = 315mW

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 3.0V 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.

315mW = (VIN – 3.0V) 150mA

315mW = VIN·•150mA – 450mW

810mW = VIN·•150mA

VIN(max) = 5.4V

Therefore, a 3.0V application at 150mA of output current

can accept a maximum input voltage of 5.4V 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 Regulators handbook.

Fixed Regulator Applications

Figure 1. Low-Noise Fixed Voltag e Application

Figure 1 shows a standard low-noise configuration with a

47k pull-up resistor from the error flag to the input

voltage and a pull-down capacitor to ground for the

purpose of fault indication. EN (Pin 3) is connected to IN

(Pin 1) for an application where enable/shutdown is not

required. COUT = 1.0µF minimum.

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Package Information

5-Pin SOT (M5)

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Package Information (Continued)

5-Pin Thin SOT (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

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 Micrel for any damages resulting from such use or sale.

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