Datasheet MIC39101-1.8BM, MIC39101-2.5BM, MIC39101-3.3BM, MIC39101-5.0BM, MIC39100-5.0BS Datasheet (MICREL)

MIC39100/39101/39102 Micrel

MIC39100/39101/39102

1A Low-Voltage Low-Dropout Regulator

General Description

The MIC39100, MIC39101, and MIC39102 are 1A low­dropout linear voltage regulators that provide low-voltage,
high-current output from an extremely small package. Utiliz­ing Micrel’s proprietary Super βeta PNP™ pass element, the
MIC39100/1/2 offers extremely low dropout (typically 410mV
at 1A) and low ground current (typically 11mA at 1A).

The MIC39100 is a fixed output regulator offered in the
SOT-223 package. The MIC39101 and MIC39102 are fixed
and adjustable regulators, respectively, in a thermally en­hanced power 8-lead SOP (small outline package).

The MIC39100/1/2 is ideal for PC add-in cards that need to
convert from standard 5V to 3.3V, 3.3V to 2.5V or 2.5V to

1.8V. A guaranteed maximum dropout voltage of 630mV over
all operating conditions allows the MIC39100/1/2 to provide

2.5V from a supply as low as 3.13V and 1.8V from a supply
as low as 2.43V.

The MIC39100/1/2 is fully protected with overcurrent limiting,
thermal shutdown, and reversed-battery protection. Fixed
voltages of 5.0V, 3.3V, 2.5V, and 1.8V are available on
MIC39100/1 with adjustable output voltages to 1.24V on
MIC39102.

For other voltages, contact Micrel.

Features

• Fixed and adjustable output voltages to 1.24V

• 410mV typical dropout at 1A

Ideal for 3.0V to 2.5V conversion
Ideal for 2.5V to 1.8V conversion

• 1A minimum guaranteed output current

• 1% initial accuracy

• Low ground current

• Current limiting and thermal shutdown

• Reversed-battery protection

• Reversed-leakage protection

• Fast transient response

• Low-profile SOT-223 package

• Power SO-8 package

Applications

• LDO linear regulator for PC add-in cards

• PowerPC™ power supplies

• High-efficiency linear power supplies

• SMPS post regulator

• Multimedia and PC processor supplies

• Battery chargers

• Low-voltage microcontrollers and digital logic

Typical Applications

V

3.3V

IN

MIC39100

IN 2.5V

OUT

GND

2.5V/1A Regulator

10µF
tantalum

Ordering Information

Part Number Voltage Junction Temp. Range Package

MIC39100-1.8BS 1.8V –40°C to +125°C SOT-223
MIC39100-2.5BS 2.5V –40°C to +125°C SOT-223
MIC39100-3.3BS 3.3V –40°C to +125°C SOT-223
MIC39100-5.0BS 5.0V –40°C to +125°C SOT-223
MIC39101-1.8BM 1.8V –40°C to +125°C SOP-8
MIC39101-2.5BM 2.5V –40°C to +125°C SOP-8
MIC39101-3.3BM 3.3V –40°C to +125°C SOP-8
MIC39101-5.0BM 5.0V –40°C to +125°C SOP-8
MIC39102BM Adj. –40°C to +125°C SOP-8

100k

V

IN

3.3V

ENABLE

SHUTDOWN

2.5V/1A Regulator with Error Flag

MIC39101

IN

EN

GND

OUT

R1

FLG

Error
Flag
Output

2.5V

10µF
tantalum

MIC39102

IN

EN

GND

OUT

ADJ

ENABLE

SHUTDOWN

V

2.5V

IN

1.5V/1A Adjustable Regulator

R1

R2

1.5V

10µF
tantalum

Super βeta PNP 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 MIC39100/39101/39102

MIC39100/39101/39102 Micrel

Pin Configuration

GND

TAB

132

IN OUTGND

MIC39100-x.x

Fixed

SOT-223 (S)

IN

OUT

FLG

1EN
2
3
4

MIC39101-x.x

Fixed

SOP-8 (M)

8 GND

GND

7

GND

6

GND

5

IN

OUT

ADJ

1EN
2
3
4

MIC39102

Adjustable

SOP-8 (M)

8 GND

GND

7

GND

6

GND

5

Pin Description

Pin No. Pin No. Pin No. Pin Name Pin Function

MIC39100 MIC39101 MIC39102

1 1 1 EN Enable (Input): CMOS-compatible control input. Logic high = enable, logic

low or open = shutdown.

2 2 IN Supply (Input)

3 3 3 OUT Regulator Output

4 FLG Flag (Output): Open-collector error flag output. Active low = output under-

voltage.

4 ADJ Adjustment Input: Feedback input. Connect to resitive voltage-divider

network.

2, TAB 5–85–8 GND Ground

MIC39100/39101/39102 2 June 2000

MIC39100/39101/39102 Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (V
Enable Voltage (V
Storage Temperature (T

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

ESD, Note 3

) ..................................... –20V to +20V

IN

) ..................................................+20V

EN

) ....................... –65°C to +150°C

S

Operating Ratings (Note 2)

Supply Voltage (V
Enable Voltage (V
Maximum Power Dissipation (P

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

Package Thermal Resistance

) .................................. +2.25V to +16V

IN

) ..................................................+16V

EN

)..................... Note 4

D(max)

SOT-223 (θJC).....................................................15°C/W

SOP-8 (θJC).........................................................20°C/W

Electrical Characteristics

VIN = V

Symbol Parameter Condition Min Typ Max Units

V

OUT

∆V

OUT

V

DO

I

GND

I

OUT(lim)

Enable Input

V

EN

I

EN

Flag Output

I

FLG(leak)

V

FLG(do)

V

FLG

+ 1V; VEN = 2.25V; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted

OUT

Output Voltage 10mA –11%

10mA ≤ I

Line Regulation I

= 10mA, V

OUT

Load Regulation VIN = V

≤ 1A, V

OUT

OUT

+ 1V, 10mA ≤ I

OUT

+ 1V ≤ VIN ≤ 8V –22%

OUT

+ 1V ≤ VIN ≤ 16V 0.06 0.5 %

≤ 1A, 0.2 1 %

OUT

/∆T Output Voltage Temp. Coefficient, 40 100 ppm/°C

Note 5

Dropout Voltage, Note 6 I

= 100mA, ∆V

OUT

= –1% 140 200 mV

OUT

250 mV

I

Ground Current, Note 7 I

Current Limit V

= 500mA, ∆V

OUT

I

= 750mA, ∆V

OUT

= 1A, ∆V

I

OUT

= 100mA, VIN = V

OUT

I

= 500mA, VIN = V

OUT

I

= 750mA, VIN = V

OUT

I

= 1A, VIN = V

OUT

= 0V, VIN = V

OUT

OUT

= –1% 275 mV

OUT

= –1% 330 500 mV

OUT

= –1% 550 mV

410 630 mV

+ 1V 400 µA

OUT

+ 1V 4 mA

OUT

+ 1V 6.5 mA

OUT

+ 1V 11 20 mA

OUT

+ 1V 1.8 2.5 A

OUT

Enable Input Voltage logic low (off) 0.8 V

logic high (on) 2.25 V

Enable Input Current VEN = 2.25V 1 15 30 µA

75 µA

V

= 0.8V 2 µA

EN

4 µA

Output Leakage Current VOH = 16V 0.01 1 µA

2 µA

Output Low Voltage VIN = 2.250V, IOL, = 250µA, Note 9 210 300 mV

400 mV
Low Threshold % of V
High Threshold % of V

OUT
OUT

93 %

99.2 %

Hysteresis 1%

June 2000 3 MIC39100/39101/39102

MIC39100/39101/39102 Micrel

Symbol Parameter Condition Min Typ Max Units
MIC39102 Only

Reference Voltage 1.228 1.240 1.252 V

1.215 1.265 V

Note 10 1.203 1.277 V

Adjust Pin Bias Current 40 80 nA

120 nA

Reference Voltage Note 7 20 ppm/°C
Temp. Coefficient

Adjust Pin Bias Current 0.1 nA/°C
Temp. Coefficient

Note 1. Exceeding the absolute maximum ratings 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. P
Note 5. Output voltage temperature coefficient is ∆V
Note 6. VDO = VIN – V

Note 7. I
Note 8. VEN ≤ 0.8V, VIN ≤ 8V, and V
Note 9. For a 2.5V device, VIN = 2.250V (device is in dropout).
Note 10. V
Note 11. Thermal regulation is defined as the change in output voltage at a time t after a change in power dissipation is applied, excluding load or line

= (T

D(max)

voltage is the input-to-output voltage differential with the minimum input voltage being 2.25V. Minimum input operating voltage is 2.25V.

is the quiescent current. IIN = I

GND

≤ V

REF

OUT

– TA) ÷ θJA, where θJA depends upon the printed circuit layout. See “Applications Information.”

J(max)

OUT

when V

decreases to 98% of its nominal output voltage with VIN = V

OUT

= 0V.

OUT

≤ (VIN – 1V), 2.25V ≤ V

OUT(worst case)

+ I

GND

IN

.

OUT

≤ 16V, 10mA ≤ IL ≤ 1A, TJ = T

÷ (T

J(max)

– T

MAX

J(min)

.

) where T

is +125°C and T

J(max)

+ 1V. For output voltages below 2.25V, dropout

OUT

J(min)

is –40°C.

regulation effects. Specifications are for a 200mA load pulse at VIN = 16V for t = 10ms.

MIC39100/39101/39102 4 June 2000

MIC39100/39101/39102 Micrel

0

20

40

60

80

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

PSRR (dB)

FREQUENCY (Hz)

0

20

40

60

80

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

PSRR (dB)

FREQUENCY (Hz)

Power Supply

Rejection Ratio

I

OUT

= 1A

C

OUT

= 10µF

C

IN

= 0

VIN = 3.3V
V

OUT

= 2.5V

10

100

1k

10k

100k

1M

300

350

400

450

500

550

600

-40 -20 0 20 40 60 80 100 120

DROPOUT VOLTAGE (mV)

TEMPERATURE (°C)

Dropout Voltage
vs. Temperature

3.3V

2.5V

I

LOAD

= 1A

1.8V

0

2

4

6

8

10

12

14

0 200 400 600 800 1000

GROUND CURRENT (mA)

OUTPUT CURRENT (mA)

Ground Current

vs. Output Current

2.5V

3.3V

1.8V

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

02468

GROUND CURRENT (mA)

SUPPLY VOLTAGE (V)

Ground Current

vs. Supply Voltage (3.3V)

I

LOAD

=100mA

I

LOAD

=10mA

Typical Characteristics

Power Supply

80

60

40

PSRR (dB)

20

Rejection Ratio

VIN = 5V

= 3.3V

V

OUT

I

= 1A

OUT

= 10µF

C

OUT

= 0

C

IN

0

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

10

1k

100

FREQUENCY (Hz)

10k

100k

Power Supply

80

60

40

PSRR (dB)

20

Rejection Ratio

VIN = 3.3V

= 2.5V

V

OUT

I

= 1A

OUT

= 47µF

C

OUT

= 0

C

IN

0

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

10

1k

100

FREQUENCY (Hz)

10k

100k

1M

1M

Power Supply

Rejection Ratio

VIN = 5V
V

OUT

I

= 1A

OUT

= 47µF

C

OUT

= 0

C

IN

1k

10

100

10k

Dropout Voltage

vs. Output Current

500
450
400
350
300
250
200
150
100

DROPOUT VOLTAGE (mV)

50

0

0 250 500 750 1000 1250

OUTPUT CURRENT (mA)

2.5V

1.8V
TA = 25°C

= 3.3V

100k

3.3V

1M

2.8

2.6

2.4

2.2

2.0

1.8

OUTPUT VOLTAGE (V)

1.6

1.4

2.0

1.8

1.6

1.4

1.2

1.0

June 2000 5 MIC39100/39101/39102

0.8

0.6

0.4

GROUND CURRENT (mA)

0.2
0

Dropout Characteristics

(2.5V)

I

=100mA

LOAD

I

=750mA

LOAD

I

=1A

LOAD

2 2.3 2.6 2.9 3.2 3.5

SUPPLY VOLTAGE (V)

Ground Current

vs. Supply Voltage (2.5V)

I

100mA

LOAD

=

I

10mA

LOAD

=

02468

SUPPLY VOLTAGE (V)

Dropout Characteristics

3.6
I

3.4

LOAD

3.2

3.0

2.8

2.6

OUTPUT VOLTAGE (V)

2.4

2.8 3.2 3.6 4.0 4.4

(3.3V)

=100mA

I

=750mA

LOAD

I

=1A

LOAD

SUPPLY VOLTAGE (V)

Ground Current

vs. Supply Voltage (2.5V)

35
30
25

I

20
15
10

5

GROUND CURRENT (mA)

0

02468

SUPPLY VOLTAGE (V)

LOAD

=1A

MIC39100/39101/39102 Micrel

Ground Current

vs. Supply Voltage (3.3V)

50

40

I

=1A

LOAD

30

20

10

GROUND CURRENT (mA)

0

02468

SUPPLY VOLTAGE (V)

Ground Current

vs. Temperature

20

I

= 1A

LOAD

15

10

5

GROUND CURRENT (mA)

0

-40 -20 0 20 40 60 80 100 120

2.5V

TEMPERATURE (°C)

1.8V

3.3V

Ground Current

1.0

0.8

0.6

0.4

0.2

GROUND CURRENT (mA)

vs. Temperature

I

LOAD

3.3V

2.5V

1.8V

0

-40 -20 0 20 40 60 80 100120

TEMPERATURE (°C)

Output Voltage

3.40

3.35

3.30

3.25

OUTPUT VOLTAGE (V)

3.20

vs. Temperature

Typical 3.3V

Device

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

10mA

=

Ground Current

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

GROUND CURRENT (mA)

0.5

vs. Temperature

2.5V

3.3V

1.8V

I

= 500mA

LOAD

0

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

Short Circuit

vs. Temperature

2.5

2.0

1.5

1.0

0.5

SHORT CIRCUIT CURRENT (A)

3.3V

2.5V

0

-40 -20 0 20 40 60 80 100 120

TEMPERATURE (°C)

1.8V

Error Flag

Pull-Up Resistor

6

5

FLAG HIGH

4

3

2

FLAG VOLTAGE (V)

1

0

0.01 0.1 1 10 100 100010000

(OK)

RESISTANCE (kΩ)

VIN = 5V

FLAG LOW

(FAULT)

Enable Current

vs. Temperature

12

10

8

6

4

2

ENABLE CURRENT µA)

0

-40 -20 0 20 40 60 80 100120140

VIN = V

OUT

V

= 2.4V

EN

TEMPERATURE (°C)

+ 1V

Flag-Low Voltage

250

200

150

100

FLAG VOLTAGE (mV)

vs. Temperature

FLAG-LOW

VOLTAGE

VIN = 2.25V
R

PULL-UP

50

0

-40 -20 0 20 40 60 80 100120140

TEMPERATURE (°C)

= 22kΩ

MIC39100/39101/39102 6 June 2000

MIC39100/39101/39102 Micrel

Load Transient Response

TIME (500µs/div.)

LOAD CURRENT

(500mA/div.)

OUTPUT VOL TA GE

(200mV/div.)

V

OUT

= 2.5V

C

OUT

= 47µF

1A

10mA

Functional Characteristics

Load Transient Response

V

= 2.5V

OUT

= 10µF

C

OUT

(200mV/div.)

OUTPUT VOL TA GE

1A

100mA

(500mA/div.)

LOAD CURRENT

TIME (250µs/div.)

Line Transient Response

V

= 2.5V

OUT

= 10µF

C

OUT

(50mV/div.)

OUTPUT VOL TA GE

(2V/div.)

INPUT VOL TA GE

TIME (25µs/div.)

June 2000 7 MIC39100/39101/39102

MIC39100/39101/39102 Micrel

Functional Diagrams

FLAG

IN

Ref.

MIC39100

1.240V

Thermal

Shut­down

OV I

18V

GND

LIMIT

OUT

MIC39100 Fixed Regulator Block Diagram

IN

O.V.
I

LIMIT

Ref.

1.240V1.180V

18V

OUT

EN

MIC39101

IN

EN

MIC39102

Thermal

Shut­down

MIC39101 Fixed Regulator with Flag and Enable Block Diagram

O.V.
I

LIMIT

Ref.

1.240V

Thermal

Shut­down

18V

GND

OUT

ADJ

GND

MIC39102 Adjustable Regulator Block Diagram

MIC39100/39101/39102 8 June 2000

MIC39100/39101/39102 Micrel

Applications Information

The MIC39100/1/2 is a high-performance low-dropout volt­age regulator suitable for moderate to high-current voltage
regulator applications. Its 630mV dropout voltage at full load
and overtemperature makes it especially valuable in battery­powered systems and as high-efficiency noise filters in post­regulator applications. Unlike older NPN-pass transistor de­signs, where the minimum dropout voltage is limited by the
base-to-emitter voltage drop and collector-to-emitter satura­tion voltage, dropout performance of the PNP output of these
devices is limited only by the low VCE saturation voltage.

A trade-off for the low dropout voltage is a varying base drive
requirement. Micrel’s Super βeta PNP™ process reduces
this drive requirement to only 2% of the load current.

The MIC39100/1/2 regulator is fully protected from damage
due to fault conditions. Linear current limiting is provided.
Output current during overload conditions is constant. Ther­mal shutdown disables the device when the die temperature
exceeds the maximum safe operating temperature. Tran­sient protection allows device (and load) survival even when
the input voltage spikes above and below nominal. The
output structure of these regulators allows voltages in excess
of the desired output voltage to be applied without reverse
current flow.

MIC39100-x.x

V

IN

IN OUT

C

IN

GND

Figure 1. Capacitor Requirements

Output Capacitor

The MIC39100/1/2 requires an output capacitor to maintain
stability and improve transient response. Proper capacitor
selection is important to ensure proper operation. The
MIC39100/1/2 output capacitor selection is dependent upon
the ESR (equivalent series resistance) of the output capacitor
to maintain stability. When the output capacitor is 10µF or
greater, the output capacitor should have an ESR less than
2Ω. This will improve transient response as well as promote
stability. Ultra-low-ESR capacitors (<100mΩ), such as ce­ramic chip capacitors, may promote instability. These very
low ESR levels may cause an oscillation and/or underdamp­ed transient response. A low-ESR solid tantalum capacitor
works extremely well and provides good transient response
and stability over temperature. Aluminum electrolytics can
also be used, as long as the ESR of the capacitor is <2Ω.

The value of the output capacitor can be increased without
limit. Higher capacitance values help to improve transient
response and ripple rejection and reduce output noise.

V

OUT

C

OUT

Input Capacitor

An input capacitor of 1µF or greater is recommended when
the device is more than 4 inches away from the bulk ac supply
capacitance or when the supply is a battery. Small, surface
mount, ceramic chip capacitors can be used for bypassing.
Larger values will help to improve ripple rejection by bypass­ing the input to the regulator, further improving the integrity of
the output voltage.

Error Flag

The MIC39101 features an error flag (FLG), which monitors
the output voltage and signals an error condition when this
voltage drops 5% below its expected value. The error flag is
an open-collector output that pulls low under fault conditions
and may sink up to 10mA. Low output voltage signifies a
number of possible problems, including an overcurrent fault
(the device is in current limit) or low input voltage. The flag
output is inoperative during overtemperature conditions. A
pull-up resistor from FLG to either VIN or V

is required for

OUT

proper operation. For information regarding the minimum and
maximum values of pull-up resistance, refer to the graph in
the typical characteristics section of the data sheet.

Enable Input

The MIC39101 and MIC39102 versions feature an active­high enable input (EN) that allows on-off control of the
regulator. Current drain reduces to “zero” when the device is
shutdown, with only microamperes of leakage current. The
EN input has TTL/CMOS compatible thresholds for simple
logic interfacing. EN may be directly tied to VIN and pulled up
to the maximum supply voltage

Transient Response and 3.3V to 2.5V or 2.5V to 1.8V
Conversion

The MIC39100/1/2 has excellent transient response to varia­tions in input voltage and load current. The device has been
designed to respond quickly to load current variations and
input voltage variations. Large output capacitors are not
required to obtain this performance. A standard 10µF output
capacitor, preferably tantalum, is all that is required. Larger
values help to improve performance even further.

By virtue of its low-dropout voltage, this device does not
saturate into dropout as readily as similar NPN-based de­signs. When converting from 3.3V to 2.5V or 2.5V to 1.8V, the
NPN based regulators are already operating in dropout, with
typical dropout requirements of 1.2V or greater. To convert
down to 2.5V or 1.8V without operating in dropout, NPN­based regulators require an input voltage of 3.7V at the very
least. The MIC39100 regulator will provide excellent perfor­mance with an input as low as 3.0V or 2.5V respectively. This
gives the PNP based regulators a distinct advantage over
older, NPN based linear regulators.

Minimum Load Current

The MIC39100/1/2 regulator is specified between finite loads.
If the output current is too small, leakage currents dominate
and the output voltage rises. A 10mA minimum load current
is necessary for proper regulation.

June 2000 9 MIC39100/39101/39102

MIC39100/39101/39102 Micrel

Adjustable Regulator Design

MIC39102

OUT

ENABLE

SHUTDOWN

IN

V

IN

EN

V 1.240V 1

=+

OUT

GND

ADJ

R1

R2

R1













R2

V

OUT

C

OUT

Figure 2. Adjustable Regulator with Resistors

The MIC39102 allows programming the output voltage any­where between 1.24V and the 16V maximum operating rating
of the family. Two resistors are used. Resistors can be quite
large, up to 1MΩ, because of the very high input impedance
and low bias current of the sense comparator: The resistor
values are calculated by:

V



R1 R2

=−





1.240

OUT



1





Where VO is the desired output voltage. Figure 2 shows
component definition. Applications with widely varying load
currents may scale the resistors to draw the minimum load
current required for proper operation (see above).

Power SOP-8 Thermal Characteristics

One of the secrets of the MIC39101/2’s performance is its
power SO-8 package featuring half the thermal resistance of
a standard SO-8 package. Lower thermal resistance means
more output current or higher input voltage for a given
package size.

Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a single­piece electrical and thermal conductor. This concept has
been used by MOSFET manufacturers for years, proving
very reliable and cost effective for the user.

Thermal resistance consists of two main elements, θ

JC

(junction-to-case thermal resistance) and θCA (case-to-ambi­ent thermal resistance). See Figure 3. θJC is the resistance
from the die to the leads of the package. θCA is the resistance
from the leads to the ambient air and it includes θCS (case-to-

sink thermal resistance) and θ

(sink-to-ambient thermal

SA

resistance).
Using the power SOP-8 reduces the θJC dramatically and

allows the user to reduce θCA. The total thermal resistance,

θJA (junction-to-ambient thermal resistance) is the limiting

factor in calculating the maximum power dissipation capabil­ity of the device. Typically, the power SOP-8 has a θJC of
20°C/W, this is significantly lower than the standard SOP-8
which is typically 75°C/W. θ

is reduced because pins 5

CA

through 8 can now be soldered directly to a ground plane
which significantly reduces the case-to-sink thermal resis­tance and sink to ambient thermal resistance.

Low-dropout linear regulators from Micrel are rated to a
maximum junction temperature of 125°C. It is important not
to exceed this maximum junction temperature during opera­tion of the device. To prevent this maximum junction tempera­ture from being exceeded, the appropriate ground plane heat
sink must be used.

SOP-8

θ

JA

θ

θ

JC

CA

printed circuit board

AMBIENT

ground plane

heat sink area

Figure 3. Thermal Resistance

Figure 4 shows copper area versus power dissipation with
each trace corresponding to a different temperature rise
above ambient.

From these curves, the minimum area of copper necessary
for the part to operate safely can be determined. The maxi­mum allowable temperature rise must be calculated to deter­mine operation along which curve.

900
800

)

∆TJA =

2

700
600
500
400
300
200

COPPER AREA (mm

100

0

0 0.25 0.50 0.75 1.00 1.25 1.50

40°C

50°C

55°C

65°C

75°C

85°C

POWER DISSIPATION (W)

100°C

Figure 4. Copper Area vs. Power-SOP

Power Dissipation

Figure 5. Copper Area vs. Power-SOP

900

TJ = 125°C

800

)

2

700

TA = 85°C 50°C 25°C
600
500
400
300
200

COPPER AREA (mm

100

0

0 0.25 0.50 0.75 1.00 1.25 1.50

POWER DISSIPATION (W)

Power Dissipation

MIC39100/39101/39102 10 June 2000

MIC39100/39101/39102 Micrel

∆T = T
T

J(max)

T

A(max)

– T

J(max)

A(max)

= 125°C

= maximum ambient operating temperature

For example, the maximum ambient temperature is 50°C, the

∆T is determined as follows:

∆T = 125°C – 50°C
∆T = 75°C

Using Figure 4, the minimum amount of required copper can
be determined based on the required power dissipation.
Power dissipation in a linear regulator is calculated as fol­lows:

P

= (VIN – V

D

OUT

) I

OUT

+ VIN· I

GND

If we use a 2.5V output device and a 3.3V input at an output
current of 1A, then our power dissipation is as follows:

PD = (3.3V – 2.5V) × 1A + 3.3V × 11mA
PD = 800mW + 36mW
PD = 836mW

From Figure 4, the minimum amount of copper required to
operate this application at a ∆T of 75°C is 160mm2.

Quick Method

Determine the power dissipation requirements for the design
along with the maximum ambient temperature at which the
device will be operated. Refer to Figure 5, which shows safe
operating curves for three different ambient temperatures:
25°C, 50°C and 85°C. From these curves, the minimum
amount of copper can be determined by knowing the maxi­mum power dissipation required. If the maximum ambient
temperature is 50°C and the power dissipation is as above,
836mW, the curve in Figure 5 shows that the required area of
copper is 160mm2.

The θJA of this package is ideally 63°C/W, but it will vary
depending upon the availability of copper ground plane to
which it is attached.

June 2000 11 MIC39100/39101/39102

MIC39100/39101/39102 Micrel

Package Information

3.15 (0.124)

2.90 (0.114)

C

L

2.41 (0.095)

2.21 (0.087)

0.10 (0.004)

0.02 (0.0008)

0.026 (0.65)
MAX)

0.157 (3.99)

0.150 (3.81)

0.050 (1.27)

C

L

4.7 (0.185)

4.5 (0.177)

TYP

6.70 (0.264)

6.30 (0.248)

SOT-223 (S)

PIN 1

0.020 (0.51)

0.013 (0.33)

0.0098 (0.249)

0.0040 (0.102)

3.71 (0.146)

3.30 (0.130)

1.04 (0.041)

0.85 (0.033)

1.70 (0.067)

1.52 (0.060)

0.84 (0.033)

0.64 (0.025)

7.49 (0.295)

6.71 (0.264)

16°
10°

10°

MAX

DIMENSIONS:

INCHES (MM)

DIMENSIONS:

MM (INCH)

0.38 (0.015)

0.25 (0.010)

0.91 (0.036) MIN

45°

0.010 (0.25)

0.007 (0.18)

0.064 (1.63)

0.045 (1.14)

0.197 (5.0)

0.189 (4.8)

SEATING

PLANE

0°–8°

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

8-Lead SOP (M)

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

MIC39100/39101/39102 12 June 2000