Datasheet MIC5245-3.3BMM, MIC5245-3.3BM5, MIC5245-3.1BM5, MIC5245-2.5BM5, MIC5245-2.7BM5 Datasheet (MICREL)

MIC5245 Micrel

MIC5245

150mA µCap CMOS LDO Regulator

Preliminary Information

General Description

The MIC5245 is an efficient, precise CMOS voltage regulator
optimized for ultra-low-noise applications. The MIC5245 of­fers better than 1% initial accuracy, extremely low dropout
voltage (typically 150mV at 150mA) and constant ground
current over load (typically 100µA). The MIC5245 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 MIC5245 provides a TTL logic compatible en­able pin. When disabled, power consumption drops nearly to
zero.

The MIC5245 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
and power MSO-8 packages, the MIC5245 also offers a
range of fixed output voltages.

Ordering Information

Features

• Ultralow dropout—100mV @ 100mA

• Ultralow noise—30µV(rms)

• Stability with tantalum or ceramic capacitors

• Load independent, ultralow ground current

• 150mA output current

• Current limiting

• Thermal Shutdown

• Tight load and line regulation

•“Zero” off-mode current

• 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

MIC5245-x.xBM5

V

IN

Enable

Shutdown

N (pin 3) may be

onnected directly

IN (pin 1).

EN

Part Number Marking Voltage Junction Temp. Range Package

MIC5245-2.5BM5 LS25 2.5V –40°C to +125°C SOT-23-5
MIC5245-2.7BM5 LS27 2.7V –40°C to +125°C SOT-23-5
MIC5245-2.8BM5 LS28 2.8V –40°C to +125°C SOT-23-5
MIC5245-2.85BM5 LS2J 2.85V –40°C to +125°C SOT-23-5
MIC5245-3.0BM5 LS30 3.0V –40°C to +125°C SOT-23-5
MIC5245-3.1BM5 LS31 3.1V –40°C to +125°C SOT-23-5
MIC5245-3.3BM5 LS33 3.3V –40°C to +125°C SOT-23-5
MIC5245-3.3BMM — 3.3V –40°C to +125°C MSOP-8

Other voltages available. Contact Micrel for details.

15
2
3

4

V

C

BYP

(optional)

OUT

C

OUT

SHUTDOWN

V

IN

V

OUT

C

ENABLE

OUT

MIC5245-3.3MM

1
2
3
4

C

BYP

(OPTIONAL)

8
7
6
5

Ultra-Low-Noise Regulator Application

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

June 2000 1 MIC5245

MIC5245 Micrel

Pin Configuration

GND

2

IN

13

OUTBYP

EN

IN

OUT

BYP

1
2
3
4

8-Pin MSOP (BMM)

EN

LSxx

45

MIC5245-x.xBM5

Pin Description

Pin Number Pin Number Pin Name Pin Function

Power MOS-8 SOT-23

2 1 IN Supply Input

5–8 2 GND Ground

1 3 EN Enable/Shutdown (Input): CMOS compatible input. Logic high = enable;

logic low = shutdown. Do not leave open.

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

output noise. May be left open.

3 5 OUT Regulator Output

8 GND

GND

7

GND

6

GND

5

Absolute Maximum Ratings (Note 1)

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

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

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

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

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

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

MSOP-8 (θJA)......................................................80°C/W

IN

ESD, Note 3

MIC5245 2 June 2000

MIC5245 Micrel

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

e

n

Enable Input

V

IL

V

IH

I

EN

Thermal Protection

+ 1V, VEN = V

OUT

Output Voltage Accuracy I

Line Regulation VIN = V
Load Regulation I

OUT

Dropout Voltage, Note 5 I

Quiescent Current VEN ≤ 0.4V (shutdown) 0.2 1 µA
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 2.0 1V
Enable Input Current VIL ≤ 0.4V 0.17 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.

IN; IOUT

= 0mA –11%

OUT

+ 0.1V to 6V –0.3 0 0.3 %/V

OUT

= 0.1mA to 150mA, Note 4 2.0 3.0 %

OUT

= 100µA 1.5 5 mV

OUT

I

= 50mA 50 85 mV

OUT

I

= 100mA 100 150 mV

OUT

I

= 150mA 150 200 mV

OUT

= 0mA 100 150 µA

OUT

I

= 150mA 100 µA

OUT

= 10µF, C

OUT

= 0V 160 300 mA

OUT

= 10µF, C

OUT

f = 10Hz to 100kHz

= 0.01µF, 30

BYP

= 0.01µF50dB

BYP

VIH ≥ 2.0V 1.5 µA

–22%

250 mV

µV(rms)

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

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.

June 2000 3 MIC5245

MIC5245 Micrel

Typical Characteristics

Power Supply

100

PSRR (dB)

Rejection Ratio

10k

VIN = 4V
V

OUT

100k

= 3V

1M

I

= 100µA

OUT

C

= 1µF tant

80

OUT

60

40

20

0

1E+11E+21E+31E+41E+51E+61E+7

10

1k

100

FREQUENCY (Hz)

Power Supply

100

PSRR (dB)

Rejection Ratio

10k

VIN = 4V
V

OUT

100k

= 3V

1M

I

= 150mA

OUT

C

= 1µF tant

80

OUT

60

40

20

0

1E+11E+21E+31E+4 1E+51E+61E+7

10

1k

100

FREQUENCY (Hz)

10M

10M

Power Supply

100

80

60

40

PSRR (dB)

20

Rejection Ratio

I

= 10mA

OUT

C

= 1µF tant

OUT

0

1E+11E+21E+31E+4 1E+51E+61E+7

10

1k

100

FREQUENCY (Hz)

10k

VIN = 4V
V

OUT

100k

= 3V

1M

Power Supply

100

PSRR (dB)

Rejection Ratio

80

60

40

I

= 100µA

20

VIN = 4V
V

OUT

0

1E+11E+21E+3 1E+41E+51E+61E+7

100 1k 10k 100k 1M 10M

10

OUT

C

= 10µF cer.

OUT

= 3V

C

= 0.01µF

BYP

FREQUENCY (Hz)

10M

Power Supply

100

80

60

40

PSRR (dB)

20

Rejection Ratio

I

= 100mA

OUT

C

= 1µF tant

OUT

0

1E+11E+21E+31E+4 1E+51E+61E+7

10

1k

100

FREQUENCY (Hz)

10k

VIN = 4V
V

OUT

100k

= 3V

1M

Power Supply

100

80

60

40

PSRR (dB)

20

Rejection Ratio

VIN = 4V
V

= 3V

OUT

I

= 10mA

OUT

C

= 10µF cer.

OUT

C

= 0.01µF

0

1E+11E+21E+31E+4 1E+51E+61E+7

100 1k 10k 100k 1M 10M

10

BYP

FREQUENCY (Hz)

10M

Power Supply

100

PSRR (dB)

Rejection Ratio

VIN = 4V
V

80

60

40

20

= 3V

OUT

I

= 100mA

OUT

C

= 10µF cer.

OUT

C

= 0.01µF

0

1E+11E+21E+31E+4 1E+51E+61E+7

100 1k 10k 100k 1M 10M

10

BYP

FREQUENCY (Hz)

Power Supply Ripple Rejection

vs. Voltage Drop

80
70
60
50
40
30
20

RIPPLE REJECTION (dB)

10

0

0 200 400 600 800 1000

I

= 100mA

OUT

100mA

10mA

C
C

VOLTAGE DROP (mV)

100µA

= 10µF cer.

OUT

= 0.01µF

BYP

Power Supply

100

80

60

40

PSRR (dB)

20

NOISE (µV/√Hz)

Rejection Ratio

VIN = 4V
V

= 3V

OUT

I

= 150mA

OUT

C

= 10µF cer.

OUT

C

= 0.01

BYP

0

1E+11E+21E+31E+4 1E+51E+61E+7

100 1k 10k 100k 1M 10M

10

FREQUENCY (Hz)

Noise Performance

10

IL = 100µA

1

VIN = 4V

0.1

V

= 3V

OUT

C

= 1µF cer.

OUT

C

= 0.01µF

BYP

0.01
10 100 1k 10k 100k 1M

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

FREQUENCY (Hz)

Power Supply Ripple Rejection

vs. Voltage Drop

80
70
60
50
40
30
20

RIPPLE REJECTION (dB)

10

0

0 200 400 600 800 1000

10

1

VIN = 4V

0.1

V

NOISE (µV/√Hz)

0.01
10

1E+1 1E+2 1E+3 1E+4 1E+5 1E+6

10mA100µA

I

= 100mA

OUT

C

VOLTAGE DROP (mV)

Noise Performance

= 3V

OUT

C

= 10µF cer.

OUT

C

= 0.01µF

BYP

1k

100

FREQUENCY (Hz)

10k

150mA

= 1µF

OUT

IL = 100µA

100k

1M

MIC5245 4 June 2000

MIC5245 Micrel

0

25

50

75

100

012345

QUIESCENT CURRENT (µA)

INPUT VOLTAGE (V)

0

100

200

300

400

500

600

-40-20 0 20 40 60 80 100120140

OUTPUT CURRENT (mA)

TEMPERATURE (°C)

Ground Pin Current

150

VIN = 4V
V

= 3V

OUT

125

100

75

I

QUIESCENT CURRENT (µA)

50

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

OUT

= 150mA

Ground Pin Current

95

VIN = 4V
V

= 3V

OUT

90

QUIESCENT CURRENT (µA)

85

0.1 1 10 100 500

LOAD CURRENT (mA)

Ground Pin Current

V

= 3V

OUT

I

OUT

Ground Pin Current

200

VIN = 4V
V

= 3V

OUT

150

100

50

QUIESCENT CURRENT (µA)

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

I

OUT

= 100µA

= 100µA

Ground Pin Current

100

V

= 3V

OUT

75

50

25

I

OUT

= 150mA

QUIESCENT CURRENT (µA)

0

012345

INPUT VOLTAGE (V)

Dropout Characteristics

3.5
V

OUT

3.0

RL = 30kΩ

2.5

2.0

1.5

1.0

OUTPUT VOLTAGE (V)

0.5

0

012345

300

250

200

150

100

50

DROPOUT VOLTAGE (mV)

0

0 25 50 75 100 125 150

OUTPUT CURRENT (mA)

June 2000 5 MIC5245

= 3V

RL = 30Ω

INPUT VOLTAGE (V)

Dropout Voltage

TA = 125°C

TA = 25°C

TA = -40°C

Dropout Voltage

8

I

= 100µA

LOAD

6

4

2

DROPOUT VOLTAGE (mV)

0

-40-20 0 20 40 60 80 100120140

TEMPERATURE (°C)

Short Circuit Current

VIN = 3.5V
V

= 3V

EN

300

Dropout Voltage

IL = 150mA

250

200

150

100

50

DROPOUT VOLTAGE (mV)

0

-40-20 0 20 40 60 80 100120140

TEMPERATURE (°C)

Output Voltage

3.05

3.00

2.95

2.90

OUTPUT VOLTAGE (V)

2.85

vs. Temperature

VIN = 4V

TYPICAL 3V DEVICE

I

= 100µA

LOAD

-50 0 50 100 150

TEMPERATURE (°C)

MIC5245 Micrel

Enable Pin Bias Current

2.0

1.5

1.0

0.5

ENABLE PIN CURRENT (µA)

0

-40-20 0 20 40 60 80 100120140

TEMPERATURE (°C)

Functional Characteristics

Line Transient Response

(50mV/div.)

∆ OUTPUT VOLTAGE

VIN = 4.0V

VEN = 100mV

Enable Threshold Voltage

4

3

2

VIN = 4.0V

1

THRESHOLD VOLTAGE (V)

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Load Transient Response

(100mV/div.)

∆ OUTPUT VOLTAGE

6V

V

= 3V

(2V/div.)

INPUT VOL TAGE

C

C

BYP

I

OUT

OUT

= 10µF

OUT

= 0.01µF
= 100µA

4V

OUTPUT CURRENT

TIME (10ms/div.)

Enable Pin Delay

(1V/div.)

ENABLE VOL TAGE

VIN = 4V

= 3V

V

(1V/div.)

OUTPUT VOL TAGE

C
C
I

OUT
OUT
BYP

OUT

= 10µF

= 0.01µF

= no load

TIME (20µs/div.)

(2V/div.)

ENABLE VOL TAGE

V

= 3V
C
C
I

OUT
OUT
BYP

OUT

= 10µF

= 0.01µF

= no load

(1V/div.)

OUTPUT VOL TAGE

VIN = 4V

= 3V

V

OUT

= 10µF cer.

C

OUT

= 0.01µF

C

BYP

TIME (100µs/div.)

Shutdown Delay

TIME (1ms/div.)

150mA

100µA

MIC5245 6 June 2000

MIC5245 Micrel

Block Diagrams

IN

EN

GND

Reference

Voltage

Thermal

Sensor

Under-

voltage

Lockout

Startup/

Shutdown

Control

FAULT

Quickstart/

Cancellation

Error

Amplifier

Noise

Current

Amplifier

ACTIVE SHUTDOWN

PULL

PULL

DOWN

BYP

UP

OUT

June 2000 7 MIC5245

MIC5245 Micrel

P

TT

D(max)

J(max) A

JA

=

−











θ

Applications Information

Enable/Shutdown

The MIC5245 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 MIC5245 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 MIC5245 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.

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.

Transient Response

The MIC5245 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 (100µA).

Active Shutdown

The MIC5245 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 MIC5245 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 MIC5245.

Package

SOT-23-5 (M5) 235°C/W 185°C/W 145°C/W

θθ

θJA Recommended

θθ

Minimum Footprint Copper Clad

θθ

θJA 1" Square

θθ

θθ

θ

θθ

JC

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 MIC5245-3.3BM5 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 50 C

°− °

=



235 C/W



= 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 3.3V and an output current of 150mA,
the maximum input voltage can be determined. Because this
device is CMOS and the ground current is typically 87µA over
the load range, the power dissipation contributed by the
ground current is < 1% and can be ignored for this calculation.

315mW = (VIN – 3.3V) 150mA
315mW = V
810mW = V
V

IN(max)

× 150mA – 495mW

IN

× 150mA

IN

= 5.4V

Therefore, a 3.3V 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

MIC5245 8 June 2000

MIC5245 Micrel

effects on voltage regulators, refer to the Regulator Thermals
section of Micrel’s

lators

handbook.

Designing with Low-Dropout Voltage Regu-

Fixed Regulator Applications

MIC5245-x.xBM5

V

IN

15
2
3

V

OUT

1µF

4

0.01µF

Figure 1. Ultra-Low-Noise Fixed Voltage Application

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

MIC5245-x.xBM5

V

IN

15
2
34

EN

V

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

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.

June 2000 9 MIC5245

MIC5245 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)

MIC5245 10 June 2000

MIC5245 Micrel

June 2000 11 MIC5245

MIC5245 Micrel

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

MIC5245 12 June 2000