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PDF MIC4950 Data sheet ( Hoja de datos )
| Número de pieza | MIC4950 | |
| Descripción | Hyper Speed Control 5A Buck Regulator | |
| Fabricantes | Micrel Semiconductor | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de MIC4950 (archivo pdf) en la parte inferior de esta página. Total 18 Páginas | ||
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MIC4950
Hyper Speed Control™ 5A Buck Regulator
General Description
The MIC4950 is a high-efficiency, 5A synchronous buck
regulator with ultra-fast transient response. It is perfectly
suited for supplying processor core and I/O voltages from
a 5V or 3.3V bus. The MIC4950 provides a switching
frequency up to 3.3MHz while achieving peak efficiencies
up to 95%. An additional benefit of high-frequency
operation is very low output ripple voltage throughout the
entire load range with the use of a small output capacitor.
The MIC4950 is designed for use with a very small
inductor, down to 1µH, and an output ceramic capacitor as
small as 10µF, without the need for external ripple
injection. A wide range of output capacitor types and
values can also be accommodated.
The MIC4950 supports safe start-up into a pre-biased
output, and offers short-circuit and thermal shutdown
protections.
The MIC4950 is available in 8-Pin SOIC and 10-Pin 3mm
× 4mm DFN packages with an operating junction
temperature range from –40°C to +125°C.
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
Features
Input voltage: 2.7V to 5.5V
5A output current
Up to 95% efficiency
Up to 3.3MHz operation
Safe start-up into a pre-biased output
Power Good output
Ultra-fast transient response
Low output voltage ripple
Low RDSON integrated MOSFET switches
0.01µA shutdown current
Thermal shutdown and current limit protection
Output voltage as low as 0.7V
8-Pin SOIC and 3mm × 4mm DFN-10L
–40°C to +125°C junction temperature range
Applications
DTVs
Set-top boxes
Printers
DVD players
Distributed power supplies
Typical Application
Hyper Speed Control 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
March 20, 2014
Revision 1.1
1 page  
Micrel, Inc.
Typical Characteristics
100
95
90
85
80
75
70
65
60
0
Efficiency
vs. Output Current
VIN = 5V
VOUT = 3.3V
1234
OUTPUT CURRENT (A)
5
Current Limit
vs. Input Voltage
12
10
8
6
4
2 VOUT = 1.8V
0
2.5
3.0 3.5 4.0 4.5 5.0
INPUT VOLTAGE (V)
5.5
3
2
1
0
-1
-2
4.50
Line Regulation
vs. Input Voltage
VOUT = 1.8V
IOUT = 0A
4.75
5.00
5.25
INPUT VOLTAGE (V)
5.50
100
95
90
85
80
75
70
65
60
0
Efficiency
vs. Output Current
VIN = 5.0V
VOUT = 1.8V
VIN = 3.3V
VOUT = 1.8V
1234
OUTPUT CURRENT (A)
5
12
10
8
6
4
2
0
0.0
Current Limit
vs. Feedback Voltage
VIN = 5V
VOUT = 1.8V
0.1 0.2 0.3 0.4 0.5
FEEDBACK VOLTAGE (V)
3
2
1
0
-1
-2
2.7
Line Regulation
vs. Input Voltage
VOUT = 1.8V
IOUT = 1A
3.0 3.3
INPUT VOLTAGE (V)
3.6
MIC4950
100
95
90
85
80
75
70
65
60
0
Efficiency
vs. Output Current
VIN = 3.3V
VOUT = 1.2V
VIN = 5V
VOUT = 1.2V
1234
OUTPUT CURRENT (A)
5
3.0
2.0
1.0
0.0
-1.0
-2.0
2.7
Line Regulation
vs. Input Voltage
IOUT = 0A
3.0 3.3
INPUT VOLTAGE (V)
3.6
3
2
1
0
-1
-2
4.50
Line Regulation
vs. Input Voltage
VOUT = 1.8V
IOUT = 1A
4.75
5.00
5.25
INPUT VOLTAGE (V)
5.50
March 20, 2014
5
Revision 1.1
5 Page 
Micrel, Inc.
When the required duty cycle is very low, the required
OFF time is typically far from the Minimum OFF Time limit
(about 176 ns typ). In this case, the MIC4950 operates by
delivering at each switching cycle a determined ON time
(dependent on the input voltage). A new ON time is
invoked by the error comparator when the FB voltage
falls below the regulation threshold. In this mode the
MIC4950 operates as an adaptive Constant-ON-Time
ripple controller, with nearly constant switching
frequency. Regulation takes place by controlling the
valley of the FB ripple waveform.
When higher duty cycles are required, regulation can no
longer be maintained by decreasing the OFF time below
the Minimum OFF Time limit. When this limit is reached,
then the OFF Time is no longer reduced, and the
MIC4950 smoothly transitions to an ON-time modulation
mode. In the ON-time modulation region, frequency
reduces with the increase of the required ON-time/duty
cycle, and regulation finally takes place on the peak of
the FB ripple waveform.
Note that because of the shift of the regulation threshold
between different modes, line regulation might suffer
when the input voltage and/or duty cycle variations force
the MIC4950 to switch form one regulation mode to the
other. In applications where wide input voltage variations
are expected, ensure that the line regulation is adequate
for the intended application.
MIC4950
March 20, 2014
11
Revision 1.1
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet MIC4950.PDF ] | |
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