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PDF MIC3775 Data sheet ( Hoja de datos )
| Número de pieza | MIC3775 | |
| Descripción | 750mA UCap Low-Voltage Low-Dropout Regulator | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MIC3775 (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
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MIC3775
Micrel
MIC3775
750mA µCap Low-Voltage Low-Dropout Regulator
Final
General Description
The MIC3775 is a 750mA low-dropout linear voltage regula-
tors that provides low-voltage, high-current output from an
extremely small package. Utilizing Micrel’s proprietary
Superβeta PNP™ pass element, the MIC3775 offers ex-
tremely low-dropout (typically 280mV at 750mA) and low
ground current (typically 7.5mA at 750mA).
The MIC3775 is ideal for PC add-in cards that need to convert
from standard 5V to 3.3V or 3.0V, 3.3V to 2.5V or 2.5V to 1.8V
or 1.65V. A guaranteed maximum dropout voltage of 500mV
over all operating conditions allows the MIC3775 to provide
2.5V from a supply as low as 3.0V and 1.8V or 1.5V from a
supply as low as 2.25V.
The MIC3775 is fully protected with overcurrent limiting,
thermal shutdown, and reversed-leakage protection. Fixed
and adjustable output voltage options are available with an
operating temperature range of –40°C to +125°C.
For other voltages, contact Micrel.
Features
• Fixed and adjustable output voltages to 1.24V
• 280mV typical dropout at 750mA
Ideal for 3.0V to 2.5V conversion
Ideal for 2.5V to 1.8V or 1.65V conversion
• Stable with ceramic capacitor
• 750mA minimum guaranteed output current
• 1% initial accuracy
• Low ground current
• Current limiting and thermal shutdown
• Reversed-leakage protection
• Fast transient response
• Low-profile power MSOP-8 package
Applications
• Fiber optic modules
• 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
MIC3775-1.5BMM
MIC3775-1.65BMM
MIC3775-1.8BMM
MIC3775-2.5BMM
MIC3775-3.0BMM
MIC3775-3.3BMM
MIC3775BMM
Voltage
1.5V
1.65V
1.8V
2.5V
3.0V
3.3V
Adj.
Junction Temp. Range
–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
Package
MSOP-8
MSOP-8
MSOP-8
MSOP-8
MSOP-8
MSOP-8
MSOP-8
Typical Applications
Dropout
vs. Output Current
300
VIN
2.5V
ENABLE
SHUTDOWN
MIC3775BMM
IN OUT
EN ADJ
GND
R1
R2
1.25V
10µF
ceramic
250 1.8VOUT
200
150 3.3VOUT
100 2.5VOUT
1.25V/750mA Adjustable Regulator
Superβeta PNP is a trademark of Micrel, Inc.
PowerPC is a trademark of Motorola
50
0
0 0.25 0.5 0.75
OUTPUT CURRENT (A)
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
March 2003
1
MIC3775
1 page  
MIC3775
Typical Characteristics
Power Supply
Rejection Ratio
80
70
VIN = 5V
VOUT = 3.3V
60
50
40
30 IOUT=750mA
20 COUT =10µF
10 CIN =0
0
0.01 0.1 1 10 100 1000
FREQUENCY (KHz)
Power Supply
Rejection Ratio
80
70
VIN =3.3V
VOUT =2.5V
60
50
40
30 IOUT=750mA
20 COUT =47µF
10 CIN =0
0
0.01 0.1 1 10 100 1000
FREQUENCY (KHz)
Dropout Characteristics
(1.5V)
1.6
1.4
1.2
1.0
0.8 10mA Load
0.6
0.4 750mA Load
0.2
0
1.5 1.7 1.9 2.1 2.3 2.5
INPUT VOLTAGE (V)
Dropout Characteristics
(3.3V)
4.0
3.5
3.0
2.5
2.0 750mA Load
1.5
10mA Load
1.0
0.5
0
1.5 2 2.5 3 3.5 4 4.5
INPUT VOLTAGE (V)
March 2003
Power Supply
Rejection Ratio
80
70
VIN =5V
VOUT =3.3V
60
50
40
30 IOUT=750mA
20 COUT =47µF
10 CIN =0
0
0.01 0.1 1 10 100 1000
FREQUENCY (KHz)
Dropout
vs. Output Current
300
250 1.8VOUT
200
150 3.3VOUT
100 2.5VOUT
50
0
0 0.25 0.5 0.75
OUTPUT CURRENT (A)
Dropout Characteristics
(1.8V)
2.0
1.8
1.6
1.4 750mA Load
1.2
1.0 10mA Load
0.8
0.6
0.4
0.2
0
1.5 2 2.5 3
INPUT VOLTAGE (V)
Ground Current
vs. Output Current
7
6 2.5VOUT
5
4
3
2
1 3.3VOUT
0
0 0.25 0.5 0.75
OUTPUT CURRENT (A)
5
Micrel
Power Supply
Rejection Ratio
80
70
VIN =3.3V
VOUT =2.5V
60
50
40
30 IOUT=750mA
20 COUT =10µF
10 CIN =0
0
0.01 0.1 1
10 100 1000
FREQUENCY (KHz)
Dropout
vs. Temperature
400
350
300
250 2.5VOUT
200
150
100
50
0
-40 -20 0 20 40 60 80 100 120
TEMPERATURE (°C)
Dropout Characteristics
(2.5V)
3.0
2.5
2.0
750mA Load
1.5
1.0 10mA Load
0.5
0
1.5 2 2.5 3 3.5
INPUT VOLTAGE (V)
Ground Current
vs. Supply Voltage (1.5V)
0.8
0.7
0.6 100mA
0.5
0.4
0.3
0.2
0.1 10mA
0
0123456
INPUT VOLTAGE (V)
MIC3775
5 Page 
MIC3775
Adjustable Regulator Design
VIN
ENABLE
SHUTDOWN
MIC3775
IN OUT
EN ADJ
GND
R1
R2
VOUT
COUT
VOUT = 1.240V 1+ RR21
Figure 2. Adjustable Regulator with Resistors
The MIC3775 allows programming the output voltage any-
where between 1.24V and the 6V 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:
R1 =
R2
VOUT
1.240
−
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 MSOP-8 Thermal Characteristics
One of the secrets of the MIC3775’s performance is its power
MSOP-8 package featuring half the thermal resistance of a
standard MSOP-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 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.
Thermal resistance consists of two main elements, θJC
(junction-to-case thermal resistance) and θCA (case-to-ambi-
ent 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-
Micrel
sink thermal resistance) and θSA (sink-to-ambient thermal
resistance).
Using the power MSOP-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 capabil-
ity of the device. Typically, the power MSOP-8 has a θJA of
80°C/W, this is significantly lower than the standard MSOP-8
which is typically 160°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 resis-
tance 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 opera-
tion of the device. To prevent this maximum junction tempera-
ture from being exceeded, the appropriate ground plane
heatsink must be used.
MSOP-8
θJA
θJC θCA
ground plane
heat sink area
AMBIENT
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 maxi-
mum allowable temperature rise must be calculated to deter-
mine operation along which curve.
900
800
700
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-MSOP
Power Dissipation (∆TJA)
900
800 TJ = 125°C
700 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 5. Copper Area vs. Power-MSOP
Power Dissipation (TA)
March 2003
11
MIC3775
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet MIC3775.PDF ] | |
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