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PDF MIC2207 Data sheet ( Hoja de datos )
| Número de pieza | MIC2207 | |
| Descripción | 3mmx3mm 2MHz 3A PWM Buck Regulator | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MIC2207 (archivo pdf) en la parte inferior de esta página. Total 21 Páginas | ||
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MIC2207
www.DataSheet4U.com
3mmx3mm 2MHz 3A PWM Buck
Regulator
General Description
The Micrel MIC2207 is a high efficiency PWM buck
(step-down) regulators that provides up to 3A of
output current. The MIC2207 operates at 2MHz and
has proprietary internal compensation that allows a
closed loop bandwidth of over 200KHz.
The low on-resistance internal p-channel MOSFET
of the MIC2207 allows efficiencies over 94%,
reduces external components count and eliminates
the need for an expensive current sense resistor.
The MIC2207 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 MIC2207 is available in the exposed pad 3mm x
3mm MLF-12L package with a junction operating
range from –40°C to +125°C.
Features
• 2.7 to 5.5V supply voltage
• 2MHz PWM mode
• Output current to 3A
• >94% efficiency
• 100% maximum duty cycle
• Adjustable output voltage option down to 1V
• Ultra-fast transient response
• Ultra-small external components
Stable with a 1µH inductor and a 4.7µF
output capacitor
• Fully integrated 3A MOSFET switch
• Micropower shutdown
• Thermal shutdown and current limit
protection
• Pb-free 3mm x 3mm MLF-12L 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
MIC2207
3A 2MHz Buck Regulator
MIC2207
3.3V Efficiency
96 OUT
94 4.5VIN
92
90 5VIN 5.5VIN
88
86
84
82
800 0.5 1 1.5 2 2.5 3
OUTPUT CURRENT (A)
Micrel, Inc • 2180 Fortune Drive • San Jose, Ca 95131 • USA • tel +1 (408) 944-0800 • fax +1 (408) 474-1000 • http://www.micrel.com
April 2005
M9999-040705
www.micrel.com
1 page  
Micrel
Typical Characteristics cont.
SUPPLY VOLTAGE (V)
Feedback Voltage
vs. Supply Voltage
1.2
1
0.8
0.6
0.4
0.2
VEN = VIN
00 1 2 3 4 5
SUPPLY VOLTAGE (V)
R
DSON
160 vs. Temperature
140
120
100
80
60
40
20 3.3VIN
0
TEMPERATURE (°C)
Max. Continuous Output
vs. Ambient Temp. 3.3V *
3.5 OUT
3.0 5VIN
2.5
2.0
1.5
1.0 *Using Recommended
Layout (1oz. Copper
0.5 and
060B.O.7M0. 80 90 100 110 120
AMBIENT 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
TEMPERATURE (°C)
Quiescent Current
vs. Supply Voltage
900
800
700
600
500
400
300
200
100
00
VEN = VIN
12345
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)
Max Continuous Current
vs. Ambient Temp. 2.5V *
3.5 OUT
3
2.5 3.3VIN
2
5VIN
1.5
1
0.5
*Using recommended
layout (1oz. copper) and
060B.O.7M0. 80 90 100 110 120
AMBIENT TEMPERATURE (°C)
April 2005
5
MIC2207
www.DataSheet4U.com
Frequency
2.500
vs. Temperature
2.400
2.300
2.200
2.100
2.000
1.900
1.800
1.700
1.600 VIN = 3.3V
1.500
TEMPERATURE (°C)
120
115
110
105
100
95
90
85
80
75
720.7
R
DSON
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
3.3VIN
0
TEMPERATURE (°C)
Max Continuous Current
vs. Ambient Temp. 1.8V *
3.5 OUT
3 5VIN
2.5 3.3VIN
2
1.5
1
0.5
*Using recommended
layout (1oz. copper) and
060B.O.7M0. 80 90 100 110 120
AMBIENT TEMPERATURE (°C)
M9999-040705
www.micrel.com
5 Page 
Micrel
Therefore, peak to peak ripple current is;
Ipk −pk
=
(V IN − VOUT
)×
VOUT
VIN
2MHz × L
Since the average peak to peak current is equal to
the load current. The actual peak (or highest current
the inductor will see in a steady state condition) is
equal to the output current plus ½ the peak to peak
current.
Ipk
= IOUT
+
(VIN
−
VOUT )×
VOUT
VIN
2 × 2MHz × L
Figure 4 demonstrates the off-time. During the off-
time, the high-side internal P-channel MOSFET
turns off. Since the current in the inductor has to
discharge, the current flows through the free-
wheeling Schottky diode to the output. In this case,
the inductor discharge rate is (where VD is the diode
forward voltage);
−
(VOUT +
L
VD
)
The total off time can be calculated as;
TOFF
=
1− D
2MHz
Figure 4. Off-Time
Discontinuous Operation
Discontinuous operation is when the inductor current
discharges to zero during the off cycle. Figure 5.
demonstrates the switch voltage and inductor
currents during discontinuous operation.
MIC2207
www.DataSheet4U.com
Figure 5. Discontinuous Operation
When the inductor current (IL) has completely
discharged, the voltage on the switch node rings at
the frequency determined by the parasitic
capacitance and the inductor value. In figure 5, it is
drawn as a DC voltage, but to see actual operation
(with ringing) refer to the functional characteristics.
Discontinuous mode of operation has the advantage
over full PWM in that at light loads, the MIC2207 will
skip pulses as nessasary, reducing gate drive
losses, drastically improving light load efficiency.
Efficiency Considerations
Calculating the efficiency is as simple as measuring
power out and dividing it by the power in;
Efficiency
=
POUT
PIN
× 100
Where input power (PIN) is;
PIN = VIN × IIN
and output power (POUT) is calculated as;
POUT = VOUT × IOUT
The Efficiency of the MIC2207 is determined by
several factors.
• Rdson (Internal P-channel Resistance)
• Diode conduction losses
• Inductor Conduction losses
• Switching losses
Rdson losses are caused by the current flowing
through the high side P-channel MOSFET. The
amount of power loss can be approximated by;
PSW = RDSON × IOUT 2 × D
April 2005
11 M9999-040705
www.micrel.com
11 Page | ||
| Páginas | Total 21 Páginas | |
| PDF Descargar | [ Datasheet MIC2207.PDF ] | |
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