Micrel MIC39100-2.5BS 1a low-voltage low-dropout regulator Datasheet

MIC39100/39101/39102
Micrel
MIC39100/39101/39102
1A Low-Voltage Low-Dropout Regulator
General Description
Features
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.
• 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
•
•
•
•
•
•
•
For other voltages, contact Micrel.
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
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
Typical Applications
100k
VIN
3.3V
MIC39100
IN
OUT
GND
VIN
3.3V
2.5V
10µF
tantalum
ENABLE
SHUTDOWN
2.5V/1A Regulator
Error
Flag
Output
MIC39101
IN
OUT
2.5V
R1
EN
FLG
GND
10µF
tantalum
2.5V/1A Regulator with Error Flag
VIN
2.5V
ENABLE
SHUTDOWN
MIC39102
IN
OUT
1.5V
R1
EN
ADJ
GND
R2
10µF
tantalum
1.5V/1A Adjustable Regulator
Super βeta PNP is a trademark of Micrel, Inc.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
June 2000
1
MIC39100/39101/39102
MIC39100/39101/39102
Micrel
Pin Configuration
GND
TAB
1
IN
2
3
GND OUT
MIC39100-x.x
Fixed
SOT-223 (S)
EN 1
8 GND
EN 1
8 GND
IN 2
7 GND
IN 2
7 GND
OUT 3
6 GND
OUT 3
6 GND
FLG 4
5 GND
ADJ 4
5 GND
MIC39101-x.x
Fixed
SOP-8 (M)
MIC39102
Adjustable
SOP-8 (M)
Pin Description
Pin No.
Pin No.
Pin No.
MIC39100 MIC39101 MIC39102
1
3
Pin Function
1
1
EN
Enable (Input): CMOS-compatible control input. Logic high = enable, logic
low or open = shutdown.
2
2
IN
Supply (Input)
3
3
OUT
Regulator Output
FLG
Flag (Output): Open-collector error flag output. Active low = output undervoltage.
4
ADJ
Adjustment Input: Feedback input. Connect to resitive voltage-divider
network.
5–8
GND
Ground
4
2, TAB
Pin Name
5–8
MIC39100/39101/39102
2
June 2000
MIC39100/39101/39102
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (VIN) ..................................... –20V to +20V
Enable Voltage (VEN) .................................................. +20V
Storage Temperature (TS) ....................... –65°C to +150°C
Lead Temperature (soldering, 5 sec.) ....................... 260°C
ESD, Note 3
Supply Voltage (VIN) .................................. +2.25V to +16V
Enable Voltage (VEN) .................................................. +16V
Maximum Power Dissipation (PD(max))..................... Note 4
Junction Temperature (TJ) ....................... –40°C to +125°C
Package Thermal Resistance
SOT-223 (θJC) ..................................................... 15°C/W
SOP-8 (θJC) ......................................................... 20°C/W
Electrical Characteristics
VIN = VOUT + 1V; VEN = 2.25V; TJ = 25°C, bold values indicate –40°C ≤ TJ ≤ +125°C; unless noted
Symbol
Parameter
Condition
VOUT
Output Voltage
10mA
10mA ≤ IOUT ≤ 1A, VOUT + 1V ≤ VIN ≤ 8V
Line Regulation
IOUT = 10mA, VOUT + 1V ≤ VIN ≤ 16V
Load Regulation
VIN = VOUT + 1V, 10mA ≤ IOUT ≤ 1A,
∆VOUT/∆T
Output Voltage Temp. Coefficient,
Note 5
VDO
Dropout Voltage, Note 6
Min
Max
Units
1
2
%
%
0.06
0.5
%
0.2
1
%
40
100
ppm/°C
IOUT = 100mA, ∆VOUT = –1%
140
200
250
mV
mV
IOUT = 500mA, ∆VOUT = –1%
275
IOUT = 750mA, ∆VOUT = –1%
330
500
mV
410
550
630
mV
mV
–1
–2
IOUT = 1A, ∆VOUT = –1%
IGND
IOUT(lim)
Typ
mV
IOUT = 100mA, VIN = VOUT + 1V
400
µA
IOUT = 500mA, VIN = VOUT + 1V
4
mA
IOUT = 750mA, VIN = VOUT + 1V
6.5
mA
IOUT = 1A, VIN = VOUT + 1V
11
20
mA
Current Limit
VOUT = 0V, VIN = VOUT + 1V
1.8
2.5
A
Enable Input Voltage
logic low (off)
0.8
V
Ground Current, Note 7
Enable Input
VEN
logic high (on)
IEN
Enable Input Current
VEN = 2.25V
2.25
1
V
15
VEN = 0.8V
30
75
µA
µA
2
4
µA
µA
Flag Output
IFLG(leak)
Output Leakage Current
VOH = 16V
0.01
1
2
µA
µA
VFLG(do)
Output Low Voltage
VIN = 2.250V, IOL, = 250µA, Note 9
210
300
400
mV
mV
VFLG
Low Threshold
% of VOUT
High Threshold
% of VOUT
93
99.2
Hysteresis
June 2000
%
1
3
%
%
MIC39100/39101/39102
MIC39100/39101/39102
Symbol
Parameter
Micrel
Condition
Min
Typ
Max
Units
1.228
1.215
1.203
1.240
1.252
1.265
1.277
V
V
V
40
80
120
nA
nA
MIC39102 Only
Reference Voltage
Note 10
Adjust Pin Bias Current
Reference Voltage
Temp. Coefficient
Note 7
Adjust Pin Bias Current
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.
20
ppm/°C
0.1
nA/°C
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 ∆VOUT(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.
MIC39100/39101/39102
4
June 2000
MIC39100/39101/39102
Micrel
Typical Characteristics
Power Supply
Rejection Ratio
Power Supply
Rejection Ratio
80
80
80
VIN = 5V
VOUT = 3.3V
VIN = 5V
VOUT = 3.3V
60
PSRR (dB)
40
IOUT = 1A
COUT = 47µF
CIN = 0
0
1E+1
1k 1E+4
10k 1E+5
1M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
20 IOUT = 1A
COUT = 10µF
CIN = 0
0
1E+1
1k 1E+4
10k 1E+5
1M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
Dropout Voltage
vs. Output Current
Dropout Voltage
vs. Temperature
Power Supply
Rejection Ratio
40
20 IOUT = 1A
COUT = 47µF
CIN = 0
0
1E+1
1k 1E+4
10k 1E+5
1M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
500
450
2.6
2.2
ILOAD =750mA
ILOAD =1A
1.6
2.3
2.6
2.9
3.2
SUPPLY VOLTAGE (V)
TA = 25°C
100
50
0
500
450
350
300
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Ground Current
vs. Output Current
14
ILOAD =100mA
3.4
3.2
3.0
ILOAD =750mA
2.8
ILOAD =1A
2.6
3.2
3.6
4.0
SUPPLY VOLTAGE (V)
Ground Current
vs. Supply Voltage (2.5V)
GROUND CURRENT (mA)
ILOAD =100mA
1.2
1.0
0.8
0.6
0.4
ILOAD =10mA
0.2
0
0
June 2000
2
4
6
SUPPLY VOLTAGE (V)
8
10
8
6
25
ILOAD =1A
15
10
5
1.8V
2.5V
3.3V
4
2
200 400 600 800 1000
OUTPUT CURRENT (mA)
Ground Current
vs. Supply Voltage (3.3V)
1.4
30
20
12
0
0
4.4
35
1.6
1.4
2.5V
400
Dropout Characteristics
(3.3V)
Ground Current
vs. Supply Voltage (2.5V)
2.0
1.8
1.8V
3.3V
250 500 750 1000 1250
OUTPUT CURRENT (mA)
2.4
2.8
3.5
ILOAD = 1A
550
0
1.4
2
1.8V
200
150
OUTPUT VOLTAGE (V)
2.4
1.8
3.3V
300
250
3.6
ILOAD =100mA
2.0
2.5V
400
350
Dropout Characteristics
(2.5V)
2.8
600
GROUND CURRENT (mA)
PSRR (dB)
60
DROPOUT VOLTAGE (mV)
VIN = 3.3V
VOUT = 2.5V
DROPOUT VOLTAGE (mV)
20
80
40
GROUND CURRENT (mA)
40
20 IOUT = 1A
COUT = 10µF
CIN = 0
0
1E+1
1k 1E+4
10k 1E+5
1M
10 1E+2
100k 1E+6
100 1E+3
FREQUENCY (Hz)
OUTPUT VOLTAGE (V)
VIN = 3.3V
VOUT = 2.5V
60
PSRR (dB)
PSRR (dB)
60
GROUND CURRENT (mA)
Power Supply
Rejection Ratio
1.2
1.0
ILOAD =100mA
0.8
0.6
ILOAD =10mA
0.4
0.2
0
0
0
2
4
6
SUPPLY VOLTAGE (V)
5
8
0
2
4
6
SUPPLY VOLTAGE (V)
8
MIC39100/39101/39102
MIC39100/39101/39102
Micrel
1.0
GROUND CURRENT (mA)
ILOAD =1A
30
20
10
0.8
0.6
3.3V
0.4
0.2
8
ILOAD = 1A
15
1.8V
2.5V
10
3.3V
5
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
3.40
3.35
3.25
3.20
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
12
FLAG VOLTAGE (V)
4
FLAG HIGH
(OK)
3
2
1
0
0.01 0.1
FLAG LOW
(FAULT)
1
10 100 100010000
RESISTANCE (kΩ)
MIC39100/39101/39102
ENABLE CURRENT µA)
6
5
Typical 3.3V
Device
3.30
Error Flag
Pull-Up Resistor
VIN = 5V
1.8V
5.0
4.5
10
Enable Current
vs. Temperature
VIN = VOUT + 1V
VEN = 2.4V
8
6
4
2
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
6
Ground Current
vs. Temperature
2.5V
3.3V
4.0
3.5
3.0
2.5
1.8V
2.0
1.5
1.0
ILOAD = 500mA
0.5
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Output Voltage
vs. Temperature
Ground Current
vs. Temperature
OUTPUT VOLTAGE (V)
GROUND CURRENT (mA)
20
2
4
6
SUPPLY VOLTAGE (V)
2.5V
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
0
0
ILOAD =10mA
SHORT CIRCUIT CURRENT (A)
40
2.5
2.0
Short Circuit
vs. Temperature
3.3V
1.5
2.5V
1.8V
1.0
0.5
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
250
FLAG VOLTAGE (mV)
GROUND CURRENT (mA)
50
Ground Current
vs. Temperature
GROUND CURRENT (mA)
Ground Current
vs. Supply Voltage (3.3V)
200
Flag-Low Voltage
vs. Temperature
FLAG-LOW
VOLTAGE
150
100
VIN = 2.25V
RPULL-UP = 22kΩ
50
0
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (°C)
June 2000
MIC39100/39101/39102
Micrel
Functional Characteristics
Load Transient Response
OUTPUT VOLTAGE
(200mV/div.)
OUTPUT VOLTAGE
(200mV/div.)
Load Transient Response
VOUT = 2.5V
COUT = 10µF
VOUT = 2.5V
COUT = 47µF
1A
LOAD CURRENT
(500mA/div.)
LOAD CURRENT
(500mA/div.)
1A
100mA
TIME (250µs/div.)
10mA
TIME (500µs/div.)
VOUT = 2.5V
COUT = 10µF
INPUT VOLTAGE
(2V/div.)
OUTPUT VOLTAGE
(50mV/div.)
Line Transient Response
TIME (25µs/div.)
June 2000
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MIC39100/39101/39102
MIC39100/39101/39102
Micrel
Functional Diagrams
OUT
IN
OV ILIMIT
1.240V
Ref.
18V
Thermal
Shutdown
MIC39100
GND
MIC39100 Fixed Regulator Block Diagram
OUT
IN
O.V.
ILIMIT
1.180V
FLAG
Ref.
18V
1.240V
EN
Thermal
Shutdown
GND
MIC39101
MIC39101 Fixed Regulator with Flag and Enable Block Diagram
OUT
IN
O.V.
ILIMIT
Ref.
18V
1.240V
ADJ
EN
Thermal
Shutdown
GND
MIC39102
MIC39102 Adjustable Regulator Block Diagram
MIC39100/39101/39102
8
June 2000
MIC39100/39101/39102
Micrel
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 VOUT is required 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
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.
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.
VIN
MIC39100-x.x
IN
CIN
VOUT
OUT
GND
COUT
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.
June 2000
9
MIC39100/39101/39102
MIC39100/39101/39102
Micrel
sink thermal resistance) and θSA (sink-to-ambient thermal
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. θCA is reduced because pins 5
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.
Adjustable Regulator Design
VIN
MIC39102
OUT
IN
VOUT
R1
ENABLE
SHUTDOWN
EN
ADJ
GND
COUT
R2
 R1
VOUT = 1.240V 1 +

 R2 
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  OUT − 1
 1.240 
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, θJC
(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-
SOP-8
θJA
θJC
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.
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.
COPPER AREA (mm2)
∆TJA =
100°C
900
40°C
50°C
55°C
65°C
75°C
85°C
COPPER AREA (mm2)
700
600
500
400
300
200
100
0
0
ground plane
heat sink area
AMBIENT
900
800
θCA
800
T = 125°C
J
700
TA = 85°C
50°C 25°C
600
500
400
300
200
100
0
0
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
Figure 4. Copper Area vs. Power-SOP
Power Dissipation
MIC39100/39101/39102
0.25 0.50 0.75 1.00 1.25 1.50
POWER DISSIPATION (W)
Figure 5. Copper Area vs. Power-SOP
Power Dissipation
10
June 2000
MIC39100/39101/39102
Micrel
∆T = TJ(max) – TA(max)
TJ(max) = 125°C
TA(max) = 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:
PD = (VIN – VOUT) IOUT + VIN · IGND
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.
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.
June 2000
11
MIC39100/39101/39102
MIC39100/39101/39102
Micrel
Package Information
3.15 (0.124)
2.90 (0.114)
CL
3.71 (0.146) 7.49 (0.295)
3.30 (0.130) 6.71 (0.264)
CL
2.41 (0.095)
2.21 (0.087)
1.04 (0.041)
0.85 (0.033)
4.7 (0.185)
4.5 (0.177)
0.10 (0.004)
0.02 (0.0008)
DIMENSIONS:
MM (INCH)
6.70 (0.264)
6.30 (0.248)
1.70 (0.067)
16°
1.52 (0.060)
10°
10°
MAX
0.38 (0.015)
0.25 (0.010)
0.84 (0.033)
0.64 (0.025)
0.91 (0.036) MIN
SOT-223 (S)
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
0.064 (1.63)
0.045 (1.14)
45°
0.0098 (0.249)
0.0040 (0.102)
0.197 (5.0)
0.189 (4.8)
0°–8°
SEATING
PLANE
0.010 (0.25)
0.007 (0.18)
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
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
USA
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
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