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Número de pieza | MIC4722 | |
Descripción | 3mm x 3mm 2.7MHz 3A PWM Buck Regulator | |
Fabricantes | Micrel Semiconductor | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de MIC4722 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
No Preview Available ! MIC4722
3mm x 3mm 2.7MHz 3A PWM Buck Regulator
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The Micrel MIC4722 is a high efficiency PWM buck (step-
down) regulator that provides up to 3A of output current.
The MIC4722 operates at 2.7MHz that makes it suitable
for next generation XDSL modems requiring operating
frequencies in excess of 2.4MHz and has proprietary
internal compensation that allows a closed loop bandwidth
of over 200KHz.
The low on-resistance internal p-channel MOSFET of the
MIC4722 allows efficiencies over 92%, reduces external
components count and eliminates the need for an
expensive current sense resistor.
The MIC4722 operates from 2.7V to 5.5V input and the
output can be adjusted down to 1V. The devices can
operate with a maximum duty cycle of 100% for use in low-
dropout conditions.
The MIC4722 is available in the exposed pad 12-pin
3mm x 3mm MLF® package with a junction operating
range from –40°C to +125°C.
Features
• 2.7 to 5.5V supply voltage
• 2.7MHz PWM mode
• Output current to 3A
• >92% efficiency
• 100% maximum duty cycle
• Adjustable output voltage option down to 1V
• Ultra-fast transient response
• Ultra-small external components
Stable with a 0.47µH inductor and a 4.7µF output
capacitor
• Fully integrated 3A MOSFET switch
• Micropower shutdown
• Thermal shutdown and current limit protection
• Pb-free 12-pin 3mm x 3mm MLF® package
• –40°C to +125°C junction temperature range
Applications
• 5V or 3.3V Point of Load Conversion
• Telecom/Networking Equipment
• Set Top Boxes
• Storage Equipment
• Video Cards
Typical Application
MIC4722
3A 2.7MHz Buck Regulator
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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
September 2007
M9999-090507-B
1 page Micrel, Inc.
Typical Characteristics (cont.)
1.0010
Line Regulation
1.0008
1.0006
1.0004
www.da1ta.0s0h0e2et4u.com
1.0000
0.9998
0.9996
0.9994
0.9992
0.99920.7 3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
Feedback Voltage
vs. Supply Voltage
1.2
1.0
0.8
0.6
0.4
0.2
VEN = VIN
00 1 2 3 4 5
SUPPLY VOLTAGE (V)
RDSON
vs. Temperature
160
140
120
100
80
60
40
20 VIN = 3.3V
0 20 40 60 80
TEMPERATURE (°C)
Feedback Voltage
1.010
vs. Temperature
1.008
1.006
1.004
1.002
1.000
0.998
0.996
0.994
0.992 VIN = 3.3V
0.990
20 40 60 80
TEMPERATURE (°C)
800
700
600
500
400
300
200
100
00
Quiescent Current
vs. Supply Voltage
VEN = VIN
123456
SUPPLY VOLTAGE (V)
Enable Threshold
vs. Supply Voltage
1.2
1.0
0.8
0.6
0.4
0.2
20.7 3.2 3.7 4.2 4.7
SUPPLY VOLTAGE (V)
MIC4722
Frequency
vs. Temperature
3.2
3.1
3.0
2.9
2.8
2.7
2.6
2.5
2.4
2.3 VIN = 3.3V
2.2 20 40 60 80
TEMPERATURE (°C)
120
115
110
105
100
95
90
85
80
75
720.7
RDSON
vs. Supply Voltage
3.2 3.7 4.2 4.7 5.2
SUPPLY VOLTAGE (V)
Enable Threshold
vs. Temperature
1.2
1.0
0.8
0.6
0.4
0.2
VIN = 3.3V
0 20 40 60 80
TEMPERATURE (°C)
September 2007
5 M9999-090507-B
5 Page Micrel, Inc.
high side switch, and lower duty cycles place the power
losses on the Schottky diode.
Inductor conduction losses (PL) can be calculated by
multiplying the DC resistance (DCR) times the square of
the output current;
www.daPtaLsh=eeDt4Cu.Rco×mIOUT 2
Also, be aware that there are additional core losses
associated with switching current in an inductor. Since
most inductor manufacturers do not give data on the
type of material used, approximating core losses
becomes very difficult, so verify inductor temperature
rise.
Switching losses occur twice each cycle, when the
switch turns on and when the switch turns off. This is
caused by a non-ideal world where switching transitions
are not instantaneous, and neither are currents. Figure 6
demonstrates how switching losses due to the
transitions dissipate power in the switch.
MIC4722
Figure 6. Switching Transition Losses
Normally, when the switch is on, the voltage across the
switch is low (virtually zero) and the current through the
switch is high. This equates to low power dissipation.
When the switch is off, voltage across the switch is high
and the current is zero, again with power dissipation
being low. During the transitions, the voltage across the
switch (VS-D) and the current through the switch (IS-D) are
at middle, causing the transition to be the highest
instantaneous power point. During continuous mode,
these losses are the highest. Also, with higher load
currents, these losses are higher. For discontinuous
operation, the transition losses only occur during the “off”
transition since the “on” transitions there is no current
flow through the inductor.
September 2007
11 M9999-090507-B
11 Page |
Páginas | Total 20 Páginas | |
PDF Descargar | [ Datasheet MIC4722.PDF ] |
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