MIC39100-1.8BSTR [MICROCHIP]
Fixed Positive LDO Regulator, 1.8V, 0.63V Dropout, PDSO4, SOT-223, 4 PIN;型号: | MIC39100-1.8BSTR |
厂家: | MICROCHIP |
描述: | Fixed Positive LDO Regulator, 1.8V, 0.63V Dropout, PDSO4, SOT-223, 4 PIN 光电二极管 输出元件 调节器 |
文件: | 总12页 (文件大小:446K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
MIC39100/39101/39102
1A Low-Voltage Low-Dropout Regulator
General Description
Features
TheMIC39100,MIC39101,andMIC39102are1Alow-dropout
linearvoltageregulatorsthatprovidelow-voltage,high-current
outputfromanextremelysmallpackage.UtilizingMicrel’spro-
prietary 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).
• 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
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 en-
hanced power 8-lead SOIC package.
• Current limiting and thermal shutdown
• Reversed-battery protection
• Reversed-leakage protection
• Fast transient response
• Low-profile SOT-223 package
• Power SO-8 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.Aguaranteed 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.
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
The MIC39100/1/2 is fully protected with overcurrent limit-
ing, 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.
• Low-voltage microcontrollers and digital logic
For other voltages, contact Micrel.
Typical Applications
100k
Error
Flag
Output
MIC39100
IN OUT
MIC39101
MIC39102
VIN
3.3V
VIN
3.3V
VIN
2.5V
2.5V
IN
OUT
2.5V
IN
OUT
1.5V
R1
R1
R2
ENABLE
SHUTDOWN
ENABLE
SHUTDOWN
EN
FLG
EN
ADJ
10µF
tantalum
10µF
tantalum
10µF
tantalum
GND
GND
GND
2.5V/1A Regulator
2.5V/1A Regulator with Error Flag
1.5V/1A Adjustable Regulator
Super βeta PNP is a 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
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Micrel
Ordering Information
Part Number
Voltage Junction Temp. Range
Package
Standard
RoHS Compliant
MIC39100-1.8BS MIC39100-1.8WS*
MIC39100-2.5BS MIC39100-2.5WS*
MIC39100-3.3BS MIC39100-3.3WS*
MIC39100-5.0BS MIC39100-5.0WS*
MIC39101-1.8BM MIC39101-1.8YM
MIC39101-2.5BM MIC39101-2.5YM
MIC39101-3.3BM MIC39101-3.3YM
MIC39101-5.0BM MIC39101-5.0YM
1.8V
2.5V
3.3V
5.0V
1.8V
2.5V
3.3V
5.0V
Adj.
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
SOT-223
SOT-223
SOT-223
SOT-223
SOIC-8
SOIC-8
SOIC-8
SOIC-8
SOIC-8
MIC39102BM
MIC39102YM
* RoHS compliant with ‘high-melting solder’ exemption.
Pin Configuration
GND
TAB
1
2
3
IN GND OUT
MIC39100-x.x
Fixed
SOT-223 (S)
EN
IN
1
2
3
4
8
7
6
5
GND
GND
GND
GND
EN
IN
1
2
3
4
8
7
6
5
GND
GND
GND
GND
OUT
FLG
OUT
ADJ
MIC39101-x.x
Fixed
SOIC-8 (M)
MIC39102
Adjustable
SOIC-8 (M)
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
3
4
2
3
IN
Supply (Input)
3
OUT
FLG
Regulator Output
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
5–8
5–8
GND
Ground
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MIC39100/39101/39102
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (V ).......................................–20V to +20V
Supply Voltage (V )................................... +2.25V to +16V
IN
IN
Enable Voltage (V ) ..................................................+20V
Enable Voltage (V ) ..................................................+16V
EN
EN
Storage Temperature (T ) ........................ –65°C to +150°C
Maximum Power Dissipation (P
)..................... Note 4
S
D(max)
Lead Temperature (soldering, 5 sec.)........................ 260°C
Junction Temperature (T )........................ –40°C to +125°C
J
ESD, Note 3
Package Thermal Resistance
SOT-223 (θ ) .....................................................15°C/W
JC
SOIC-8 (θ )........................................................20°C/W
JC
Electrical Characteristics(Note 12)
VIN = VOUT + 1V; VEN = 2.25V; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
VOUT
Output Voltage
10mA
–1
–2
1
2
%
%
10mA ≤ IOUT ≤ 1A, VOUT + 1V ≤ VIN ≤ 8V
Line Regulation
IOUT = 10mA, VOUT + 1V ≤ VIN ≤ 16V
VIN = VOUT + 1V, 10mA ≤ IOUT ≤ 1A,
0.06
0.2
40
0.5
1
%
%
Load Regulation
ΔVOUT/ΔT
ppm/°C
Output Voltage Temp. Coefficient,
100
Note 5
VDO
Dropout Voltage, Note 6
IOUT = 100mA, ΔVOUT = –1%
140
200
250
mV
mV
IOUT = 500mA, ΔVOUT = –1%
IOUT = 750mA, ΔVOUT = –1%
IOUT = 1A, ΔVOUT = –1%
275
330
mV
mV
500
550
630
mV
mV
410
400
4
IGND
Ground Current, Note 7
IOUT = 100mA, VIN = VOUT + 1V
IOUT = 500mA, VIN = VOUT + 1V
IOUT = 750mA, VIN = VOUT + 1V
IOUT = 1A, VIN = VOUT + 1V
µA
mA
mA
mA
A
6.5
11
20
IOUT(lim)
Enable Input
VEN
Current Limit
VOUT = 0V, VIN = VOUT + 1V
1.8
2.5
Enable Input Voltage
Enable Input Current
logic low (off)
logic high (on)
VEN = 2.25V
0.8
V
V
2.25
IEN
1
15
30
75
µA
µA
VEN = 0.8V
2
4
µA
µA
Flag Output
IFLG(leak)
Output Leakage Current
Output Low Voltage
VOH = 16V
0.01
210
1
2
µA
µA
VFLG(do)
VFLG
VIN = 2.250V, IOL, = 250µA, Note 9
300
400
mV
mV
Low Threshold
High Threshold
Hysteresis
% of VOUT
% of VOUT
93
%
%
%
99.2
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Micrel
Symbol
Parameter
Condition
Min
Typ
Max
Units
MIC39102 Only
Reference Voltage
1.228 1.240 1.252
V
V
V
1.215
1.203
1.265
1.277
Note 10
Note 7
Adjust Pin Bias Current
40
20
80
120
nA
nA
Reference Voltage
Temp. Coefficient
ppm/°C
Adjust Pin Bias Current
Temp. Coefficient
0.1
nA/°C
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. PD(max) = (TJ(max) – TA) ÷ θJA, where θJA depends upon the printed circuit layout. See “Applications Information.”
Note 5. Output voltage temperature coefficient is ΔVOUT(worst case) ÷ (TJ(max) – TJ(min)) where TJ(max) is +125°C and TJ(min) is –40°C.
Note 6. VDO = VIN – VOUT when VOUT decreases to 98% of its nominal output voltage with VIN = VOUT + 1V. For output voltages below 2.25V, dropout
voltage is the input-to-output voltage differential with the minimum input voltage being 2.25V. Minimum input operating voltage is 2.25V.
Note 7. IGND is the quiescent current. IIN = IGND + IOUT
.
Note 8. VEN ≤ 0.8V, VIN ≤ 8V, and VOUT = 0V.
Note 9. For a 2.5V device, VIN = 2.250V (device is in dropout).
Note 10. VREF ≤ VOUT ≤ (VIN – 1V), 2.25V ≤ VIN ≤ 16V, 10mA ≤ IL ≤ 1A, TJ = TMAX
.
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
regulation effects. Specifications are for a 200mA load pulse at VIN = 16V for t = 10ms.
Note 12. Specification for packaged product only.
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MIC39100/39101/39102
Micrel
Typical Characteristics
P ower S upply
R ejection R atio
P ower S upply
R ejection R atio
P ower S upply
R ejection R atio
80
80
60
40
20
0
80
60
40
20
0
VIN = 5V
VOUT = 3.3V
VIN = 5V
VOUT = 3.3V
VIN = 3.3V
VOUT = 2.5V
60
40
IOUT = 1A
20
IOUT = 1A
C OUT = 47µF
C IN = 0
IOUT = 1A
C OUT = 10µF
C IN = 0
C OUT = 10µF
C IN = 0
0
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
1k 10k
1M
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
1k 10k
1M
1k 10k
1M
10 100
100k
10 100
FREQUENCY (Hz)
100k
10 100
FREQUENCY (Hz)
100k
FREQUENCY (Hz)
P ower S upply
R ejection R atio
Dropout Voltage
vs . Output C urrent
Dropout Voltage
vs . Temperature
80
60
40
20
0
600
550
500
450
400
350
300
500
450
400
350
300
250
200
150
100
50
VIN = 3.3V
VOUT = 2.5V
ILOAD = 1A
2.5V
1.8V
3.3V
3.3V
1.8V
TA = 25°C
2.5V
IOUT = 1A
C OUT = 47µF
C IN = 0
0
1E+1 1E+2 1E+3 1E+4 1E+5 1E+6
1k 10k
-40 -20
0
20 40 60 80 100 120
1M
3.5
8
0
250 500 750 1000 1250
OUTPUT CURRENT (mA)
10 100
FREQUENCY (Hz)
100k
TEMPERATURE (°C)
Dropout C haracteris tics
(2.5V)
Dropout C haracteris tics
(3.3V)
G round C urrent
vs . Output C urrent
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
3.6
3.4
3.2
3.0
2.8
2.6
2.4
14
12
10
8
I
=100mA
I
=100mA
LOAD
LOAD
1.8V
2.5V
I
=750mA
3.3V
LOAD
I
=750mA
6
LOAD
I
=1A
LOAD
4
I
=1A
LOAD
2
0
0
200 400 600 800 1000
OUTPUT CURRENT (mA)
2
2.3
2.6
2.9
3.2
2.8
3.2
3.6
4.0
4.4
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
G round C urrent
vs . S upply Voltage (2.5V)
G round C urrent
vs . S upply Voltage (2.5V)
G round C urrent
vs . S upply Voltage (3.3V)
1.4
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
35
1.2
1.0
0.8
0.6
0.4
0.2
0
30
25
20
15
10
5
I
LOAD =100mA
I
=100mA
=10mA
LOAD
I
I
=1A
LOAD
LOAD
I
=10mA
LOAD
0
0
2
4
6
8
0
2
4
6
0
2
4
6
8
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
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MIC39100/39101/39102
Micrel
G round C urrent
vs . S upply Voltage (3.3V)
G round C urrent
vs . Temperature
G round C urrent
vs . Temperature
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
50
40
30
20
10
0
1.0
0.8
0.6
0.4
0.2
0
2.5V
3.3V
I
=10mA
LOAD
I
=1A
LOAD
1.8V
3.3V
2.5V
1.8V
ILOAD = 500mA
-40 -20
0
20 40 60 80 100 120
0
2
4
6
8
-40 -20
0
20 40 60 80 100 120
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
Output Voltage
vs . Temperature
G round C urrent
vs . Temperature
S hort C ircuit
vs . Temperature
20
15
10
5
3.40
3.35
3.30
3.25
3.20
2.5
2.0
1.5
1.0
0.5
0
ILOAD = 1A
2.5V
3.3V
Typical 3.3V
Device
1.8V
2.5V
1.8V
3.3V
0
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
E rror F lag
P ull-Up R es is tor
E nable C urrent
vs . Temperature
F lag-L ow Voltage
vs . Temperature
6
5
4
3
2
1
12
10
8
250
200
150
100
50
VIN = 5V
VIN = VOUT + 1V
F LAG -LOW
VOLTAG E
VE N = 2.4V
F LAG HIG H
(OK)
6
VIN = 2.25V
R P ULL-UP = 22kΩ
4
F LAG LOW
(FAULT)
2
0
0
0
0.01 0.1
1
10 100 1000 10000
-40 -20
0
20 40 60 80 100 120 140
-40 -20
0
20 40 60 80 100 120 140
RESISTANCE (kΩ)
TEMPERATURE (°C)
TEMPERATURE (°C)
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MIC39100/39101/39102
Micrel
Functional Characteristics
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MIC39100/39101/39102
Micrel
Functional Diagrams
IN
OUT
OV ILIMIT
18V
1.240V
Ref.
Thermal
Shut-
down
MIC39100
GND
MIC39100 Fixed Regulator Block Diagram
OUT
IN
O.V.
ILIMIT
18V
1.180V
1.240V
Ref.
FLAG
EN
Thermal
Shut-
down
GND
MIC39101
MIC39101 Fixed Regulator with Flag and Enable Block Diagram
OUT
IN
O.V.
ILIMIT
18V
1.240V
Ref.
ADJ
EN
Thermal
Shut-
down
GND
MIC39102
MIC39102 Adjustable Regulator Block Diagram
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August 2005
MIC39100/39101/39102
Micrel
Input Capacitor
Applications Information
An input capacitor of 1µF or greater is recommended when
thedeviceismorethan4inchesawayfromthebulkacsupply
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 bypass-
ing the input to the regulator, further improving the integrity
of the output voltage.
The MIC39100/1/2 is a high-performance low-dropout volt-
age regulator suitable for moderate to high-current voltage
regulator applications. Its 630mV dropout voltage at full load
and overtemperature makes it especially valuable in bat-
tery-powered systems and as high-efficiency noise filters in
post-regulatorapplications.UnlikeolderNPN-passtransistor
designs, where the minimum dropout voltage is limited by the
base-to-emitter voltage drop and collector-to-emitter satura-
tion voltage, dropout performance of the PNPoutput of these
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
devices is limited only by the low V saturation voltage.
CE
Atrade-off for the low dropout voltage is a varying base drive
requirement.Micrel’sSuperβetaPNP™processreducesthis
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. Ther-
mal shutdown disables the device when the die temperature
exceedsthemaximumsafeoperatingtemperature.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
pull-up resistor from FLG to either V or V
is required
IN
OUT
for 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
TheMIC39101andMIC39102versionsfeatureanactive-high
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/CMOScompatiblethresholdsforsimplelogicinterfacing.
current flow.
MIC39100-x.x
VIN
VOUT
IN
OUT
GND
CIN
COUT
EN may be directly tied to V and pulled up to the maximum
IN
supply voltage
Transient Response and 3.3V to 2.5V or 2.5V to 1.8V
Conversion
Figure 1. Capacitor Requirements
Output Capacitor
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.
The MIC39100/1/2 requires an output capacitor to maintain
stability and improve transient response. Proper capaci-
tor selection is important to ensure proper operation. The
MIC39100/1/2 output capacitor selection is dependent upon
theESR(equivalentseriesresistance)oftheoutputcapacitor
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-ESRcapacitors(<100mΩ),suchasceramic
chip capacitors, may promote instability.These very low ESR
levelsmaycauseanoscillationand/orunderdampedtransient
response.Alow-ESRsolidtantalumcapacitorworksextremely
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.
By virtue of its low-dropout voltage, this device does not satu-
rate 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 typi-
cal dropout requirements of 1.2V or greater. To convert down
to 2.5V or 1.8V without operating in dropout, NPN-based
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.
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.
Minimum Load Current
TheMIC39100/1/2regulatorisspecifiedbetweenfiniteloads.
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.
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MIC39100/39101/39102
Micrel
Adjustable Regulator Design
Using the power SOIC-8 reduces the θ dramatically and
JC
allows the user to reduce θ . The total thermal resistance,
CA
θ
(junction-to-ambient thermal resistance) is the limiting
MIC39102
JA
factor in calculating the maximum power dissipation capabil-
VIN
IN
OUT
VOUT
COUT
R1
R2
ity of the device. Typically, the power SOIC-8 has a θ of
JC
ENABLE
SHUTDOWN
EN
ADJ
20°C/W, this is significantly lower than the standard SOIC-8
GND
which is typically 75°C/W. θ is reduced because pins 5
CA
through 8 can now be soldered directly to a ground plane
whichsignificantlyreducesthecase-to-sinkthermalresistance
and sink to ambient thermal resistance.
R1
R2
VOUT = 1.240V 1+
Low-dropout linear regulators from Micrel are rated to a
maximumjunctiontemperatureof125°C.Itisimportantnotto
exceed this maximum junction temperature during operation
of the device. To prevent this maximum junction temperature
frombeingexceeded, theappropriategroundplaneheatsink
must be used.
Figure 2. Adjustable Regulator with Resistors
The MIC39102 allows programming the output voltage any-
wherebetween1.24Vandthe16Vmaximumoperatingrating
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
OUT
R1 = R2
−1
SOIC-8
1.240
Where V is the desired output voltage. Figure 2 shows
O
component definition. Applications with widely varying load
currents may scale the resistors to draw the minimum load
current required for proper operation (see above).
JA
ground plane
heat sink area
JC
CA
Power SOIC-8 Thermal Characteristics
AMBIENT
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 pack-
age size.
printed circuit board
Figure 3. Thermal Resistance
Figure 4 shows copper area versus power dissipation with
each trace corresponding to a different temperature rise
above ambient.
Lower thermal resistance is achieved by joining the four
ground leads with the die attach paddle to create a single-
piece electrical and thermal conductor. This concept has
been used by MOSFET manufacturers for years, proving
very reliable and cost effective for the user.
Fromthesecurves,theminimumareaofcoppernecessaryfor
the part to operate safely can be determined. The maximum
allowable temperature rise must be calculated to determine
operation along which curve.
Thermal resistance consists of two main elements, θ (junc-
JC
tion-to-case thermal resistance) and θ (case-to-ambient
CA
thermal resistance). See Figure 3. θ is the resistance from
JC
the die to the leads of the package. θ is the resistance
CA
from the leads to the ambient air and it includes θ (case-
CS
to-sink thermal resistance) and θ (sink-to-ambient thermal
SA
resistance).
900
800
900
T
= 125°C
800
700
600
500
400
300
200
100
0
J
∆TJ A
=
700
600
500
400
300
200
100
0
TA = 85°C
50°C 25°C
0
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
0
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
Figure 4. Copper Area vs. Power-SOIC
Power Dissipation
Figure 5. Copper Area vs. Power-SOIC
Power Dissipation
M9999-082505
10
August 2005
MIC39100/39101/39102
Micrel
Quick Method
ΔT = T
– T
A(max)
J(max)
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 maxi-
mum 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
T
= 125°C
J(max)
T
= maximum ambient operating temperature
A(max)
For example, the maximum ambient temperature is 50°C,
the ΔT is determined as follows:
ΔT = 125°C – 50°C
ΔT = 75°C
Using Figure 4, the minimum amount of required copper can
bedeterminedbasedontherequiredpowerdissipation.Power
dissipation in a linear regulator is calculated as follows:
2
of copper is 160mm .
The θ 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.
P = (V – V
) I
+ V ·I
IN GND
JA
D
IN
OUT OUT
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:
P = (3.3V – 2.5V) × 1A + 3.3V × 11mA
D
P = 800mW + 36mW
D
P = 836mW
D
From Figure 4, the minimum amount of copper required to
2
operate this application at a ΔT of 75°C is 160mm .
August 2005
11
M9999-082505-B
MIC39100/39101/39102
Micrel
Package Information
3.15 (0.124)
2.90 (0.114)
C
L
7.49 (0.295)
6.71 (0.264)
3.71 (0.146)
3.30 (0.130)
C
L
2.41 (0.095)
2.21 (0.087)
1.04 (0.041)
0.85 (0.033)
4.7 (0.185)
4.5 (0.177)
DIMENSIONS:
MM (INCH)
1.70 (0.067)
16°
6.70 (0.264)
6.30 (0.248)
1.52 (0.060)
10°
0.10 (0.004)
0.38 (0.015)
10°
0.02 (0.0008)
0.25 (0.010)
MAX
0.84 (0.033)
0.64 (0.025)
0.91 (0.036) MIN
SOT-223 (S)
8-Lead SOIC (M)
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
This 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 can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant 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.
© 2005 Micrel Incorporated
M9999-082505
12
August 2005
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