Datasheet MIC5246-3.3BM5, MIC5246-2.7BM5, MIC5246-2.85BM5, MIC5246-2.8BM5, MIC5246-3.0BM5 Datasheet (MICREL)

MIC5246 Micrel

MIC5246

150mA µCap CMOS LDO Regulator

Preliminary Information

General Description

The MIC5246 is an efficient, precise CMOS voltage regulator
optimized for low-noise applications. The MIC5246 offers
better than 1% initial accuracy, extremely-low-dropout volt­age (typically 150mV at 150mA) and constant ground current
(typically 85µA)over load . The MIC5246 features an error
flag that indicates an output fault condition such as overcurrent,
thermal shutdown and dropout. The MIC5246 provides a very
low noise output, ideal for RF applications where quiet
voltage sources are required.

Designed specifically for hand-held and battery-powered
devices, the MIC5246 provides a TTL-logic-compatible en­able pin. When disabled, power consumption drops nearly to
zero.

The MIC5246 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 MIC5246 also offers a range of fixed output
voltages.

Features

• Error flag indicates fault condition

• Ultralow dropout—100mV @ 100mA

• 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

• TTL-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

MIC5246-2.6BM5 LT26 2.6V –40°C to +125°C SOT-23-5
MIC5246-2.7BM5 LT27 2.7V –40°C to +125°C SOT-23-5
MIC5246-2.8BM5 LT28 2.8V –40°C to +125°C SOT-23-5
MIC5246-2.85BM5 LT2J 2.85V –40°C to +125°C SOT-23-5
MIC5246-3.0BM5 LT30 3.0V –40°C to +125°C SOT-23-5
MIC5246-3.3BM5 LT33 3.3V –40°C to +125°C SOT-23-5

Other voltages available. Contact Micrel for details.

47kΩ

MIC5246-x.xBM5

V

IN

15
2

Enable

Shutdown

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

34

EN

Low-Noise Regulator Application

V

OUT

C

OUT

FLG

C

FLG

IttyBitty is a trademark of Micrel, Inc.

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

June 2000 1 MIC5246

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

5 OUT Regulator Output

GND

2

IN

13

EN

LTxx

45

FLG

MIC5246-x.xBM5

logic low = shutdown. Do not leave open.

undervoltage condition.

OUT

Absolute Maximum Ratings (Note 1)

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

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

Flag Output Voltage (V

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

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

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

FLG

Operating Ratings (Note 2)

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

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

IN

Flag Output Voltage (V

IN

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

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

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

FLG

IN
IN

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

ESD, Note 3

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Electrical Characteristics

VIN = V

Symbol Parameter Conditions Min Typical Max Units

V

O

∆V

LNR

∆V

LDR

VIN – V

I

Q

I

GND

PSRR Power Supply Rejection f = 120Hz, C
I

LIM

Enable Input

V

IL

V

IH

I

EN

Thermal Protection

Error Flag

V

FLG

V

OL

I

FL

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 at 1V

Note 6. 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

Note 7. The error flag is a function of the output voltage being 5% low and the detection of one of the following: overcurrent, overtemperature or

+ 1V, VEN = V

OUT

Output Voltage Accuracy I

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

IN; IOUT

= 0mA –11%

OUT

–22%

OUT

Line Regulation VIN = V
Load Regulation I
Dropout Voltage, Note 5 I

OUT
OUT

I

OUT

I

OUT

I

OUT

+ 0.1V to 6V –0.3 0 0.3 %/V

OUT

= 0.1mA to 150mA, Note 4 23%

= 100µA 1.5 5 mV

= 50mA 50 85 mV
= 100mA 100 150 mV
= 150mA 150 200 mV

250 mV
Quiescent Current VEN ≤ 0.4V (shutdown) 0.2 1 µA
Ground Pin Current, Note 6 I

Current Limit V

= 0mA 85 150 µA

OUT

I

= 150mA 85 150 µA

OUT

= 10µF50dB

OUT

= 0V 160 300 mA

OUT

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

VIH ≥ 1.6V 0.01 µA

Shutdown Resistance Discharge 500 Ω

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

Low Threshold % of V
High Threshold % of V

(Flag ON) 90 %

OUT

(Flag OFF) 96 %

OUT

Output Logic-Low Voltage IL = 100µA, fault condition 0.02 0.4 V
Flag Leakage Current flag off, V

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.

pin current.

dropout. See “Applications Information” section for additional information.

= 6V 0.01 µA

FLG

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)

)

)

)

Typical Characteristics

Power Supply Rejection Ratio

60

50

40

30

PSRR (dB)

20

10

I

= 100µA

LOAD

0

1x1011x1021x1031x1041x1051x10

FREQUENCY (Hz

Power Supply Rejection Ratio

60

50

40

30

PSRR (dB)

20

10

I

= 150mA

0

1x1011x1021x1031x1041x1051x10

FREQUENCY (Hz

Power Supply Rejection Ratio

60

50

40

30

PSRR (dB)

20

10

I

= 50mA

LOAD

6

0

1x1011x1021x1031x1041x1051x10

FREQUENCY (Hz

6

Ground Current

vs. Output Current

90

88

86

84

82

GROUND CURRENT (µA)

6

80

0 1 10 100 1000

OUTPUT CURRENT (mA)

Power Supply Rejection Ratio

60

50

40

30

PSRR (dB)

20

10

I

= 100mA

LOAD

0

1x1011x1021x1031x1041x1051x10

FREQUENCY (Hz

Ground Pin Current

100

80

60

40

20

GROUND CURRENT (µA)

Iload = 100µA

0

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

6

Ground Pin Current

100

80

60

40

20

GROUND CURRENT (µA)

I

= 150mA

LOAD

0

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

Dropout Characteristics

4

3

2

1

VOLTAGE OUT (V)

0

012345

100µA

150mA

VOLTAGE IN (V)

Ground Pin Current

100

80

60

40

20

GROUND CURRENT (µA)

0

012345

I

LOAD

VOLTAGE IN (V)

= 100µA

Dropout Voltage

200

150

100

50

DROPOUT VOLTAGE (µV)

0

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

I

LOAD

= 100µA

Ground Pin Current

100

80

60

40

20

GROUND CURRENT (µA)

0

012345

I

= 150mA

VOLTAGE IN (V)

Dropout Voltage

250

200

150

100

50

DROPOUT VOLTAGE (µV)

0

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

I

LOAD

= 150mA

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Typical Characteristics

Short Circuit Current

400

300

200

100

SHORT CIRCUIT CURRENT (mA)

vs. Temperature

V

= 0V

0

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

OUT

Output Voltage

3.40

3.36

3.32

3.28

3.24

OUTPUT VOLTAGE (V)

3.20

vs. Temperature

-40 -10 20 50 80 110 140

TEMPERATURE (°C)

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Block Diagrams

IN

EN

Reference

Voltage

Thermal

Sensor

Under-

voltage

Lockout

Overcurrent

Dropout

Detection

Startup/

Shutdown

Control

FAULT

Quickstart

Error

Amplifier

Current

Amplifier

ACTIVE SHUTDOWN

Out of

Regulation

Detection

GND

PULL

UP

PULL

DOWN

OUT

FLG

MIC5246 6 June 2000

MIC5246 Micrel

P

TT

D(max)

J(max) A

JA

=

−











θ

Applications Information

Enable/Shutdown

The MIC5246 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 MIC5246 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 MIC5246 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.

X7R dielectric 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 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 or a tantalum capacitor to ensure the same minimum
capacitance value over the operating temperature range.
Tantalum capacitors have a very stable dielectric (10% over
their operating temperature range) and can also be used with
this device.

Error Flag

The error flag output is an active-low, open-drain output that
drives low when a fault condition AND an undervoltage
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.

Error Flag Circuit

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 downstream
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. This glitch is filtered by putting a capacitor from the error
flag to ground. The glitch does not occur if the error flag pulled
up to the output.

Transient Response

The MIC5246 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 MIC5246 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 MIC5246 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:

T

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 MIC5246.

Package θJA Recommended θJA 1" Square θ

Minimum Footprint Copper Clad

SOT-23-5 (M5) 235°C/W 185°C/W 145°C/W

JC

Table 1. SOT-23-5 Thermal Resistance

June 2000 7 MIC5246

MIC5246 Micrel

15
2
34

1µF

V

OUT

MIC5246-x.xBM5

47kΩ

V

IN

The actual power dissipation of the regulator circuit can be
determined using the equation:

= (VIN – V

P

D

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 MIC5246-3.0BM5 at 50°C with
a minimum footprint layout, the maximum input voltage for a
set output current can be determined as follows:

P

D(max)

P

D(max)



125 C 5 C

°− °

=



235 C/W



= 315mW

°



0





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
V

IN(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

lators

handbook.

Designing with Low-Dropout Voltage Regu-

Fixed Regulator Applications

Figure 1. Low-Noise Fixed Voltage Application

Figure 1 shows a standard low-noise configuration with a
47kΩ pull-up resistor from the error flag to the input voltage
and a pull-down capacitor to ground for the purpose of fault
indication.

Dual-Supply Operation

When used in dual supply systems where the regulator load
is returned to a negative supply, the output voltage must be
diode clamped to ground.

MIC5246 8 June 2000

MIC5246 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)

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MIC5246 10 June 2000

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

TEL + 1 [phone] FAX + 1 [phone] 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.

© 2000 Micrel Incorporated

MIC5246 12 June 2000