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PDF SP6134 Data sheet ( Hoja de datos )
| Número de pieza | SP6134 | |
| Descripción | 600kHz Synchronous PWM Step Down Controller | |
| Fabricantes | Exar | |
| Logotipo |  |
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January 2009
SP6134
600kHz Synchronous PWM Step Down Controller
Rev. 2.0.0
GENERAL DESCRIPTION
The SP6134 is a 600kHz constant frequency,
voltage mode, synchronous PWM step down
controller optimized for high efficiency.
The SP6134 is adequately suited for split plane
applications utilizing a low power 5V rail to
power the controller circuitry, minimizing
power dissipation. Its wide input voltage range
of 3V to 15V allows for conversions from the
standard 3.3V, 5V, 9.6V and 12V power rails
to an output voltage adjustable down to 0.8V.
Developed around a wide bandwidth internal
amplifier, the SP6134 can accommodate type
II and type III compensation schemes.
Protection features include a programmable
UVLO, thermal shutdown and output short
circuit protection.
The SP6134 is part of a larger family of step
down controllers operating at various
switching frequencies up to 1300kHz and input
voltages up to 28V. Refer to Exar’s SP6134H,
SP6132, SP6132H, SP6137 and SP6139 for
complete details.
The SP6134 is available in lead free, RoHS
compliant, space saving 10-pin MSOP
package.
APPLICATIONS
• 12V DPA
• Communications Systems
• Graphics Cards
FEATURES
• 3V to 15V Step Down Achieved Using
Dual Input
• On-Board 1.5Ω sink (2Ω source) NFET
Drivers
• Up to 15A Output Capability
• UVLO Detects Both VCC and VIN
• Short-Circuit Protection with Auto-
Restart
• Supports Type II or III Compensation
• Programmable Soft Start
• Fast Transient Response
• High Efficiency: Greater than 94%
• Non-synchronous Start-Up
• Small 10-Pin MSOP Package
• U.S. Patent #6,922,041
TYPICAL APPLICATION DIAGRAM
Fig. 1: SP6134 Application Diagram
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
www.exar.com
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
1 page  
SP6134
600kHz Synchronous PWM Step Down Controller
ORDERING INFORMATION
Part Number
SP6134CU-L
SP6134CU-L/TR
SP6134EU-L
SP6134EU-L/TR
SP6134EB
Temperature
Range
Marking
0°C≤TA≤+70°C
SP6134CU
CXXX
YWW
SP6134CU
0°C≤TA≤+70°C
CXXX
YWW
SP6134EU
-40°C≤TA≤+85°C
EXXX
YWW
SP6134EU
-40°C≤TA≤+85°C
EXXX
YWW
SP6134 Evaluation Board
Package
10 Pin MSOP
10 Pin MSOP
10 Pin MSOP
10 Pin MSOP
“YY” = Year – “WW” = Work Week – “XXX” = Lot Number
Packing
Quantity
Bulk
Tape & Reel
Bulk
Tape & Reel
Note 1
Note 2
© 2008 Exar Corporation
5/15
Rev. 2.0.0
5 Page 
SP6134
600kHz Synchronous PWM Step Down Controller
copper pad directly under the package,
without occupying additional board space, can
increase the maximum power from
approximately 1 to 1.2W. For DPAK package,
enlarging the tap mounting pad to 1 square
inches reduces the RΘJA from 96°C/W to
40°C/W.
SCHOTTKY DIODE SELECTION
When paralleled with the bottom MOSFET, an
optional Schottky diode can improve efficiency
and reduce noises. Without this Schottky
diode, the body diode of the bottom MOSFET
conducts the current during the non-overlap
time when both MOSFETs are turned off.
Unfortunately, the body diode has high
forward voltage and reverse recovery problem.
The reverse recovery of the body diode causes
additional switching noises when the diode
turns off. The Schottky diode alleviates these
noises and additionally improves efficiency
thanks to its low forward voltage. The reverse
voltage across the diode is equal to input
voltage, and the diode must be able to handle
the peak current equal to the maximum load
current.
The power dissipation of the Schottky diode is
determined by
PDiode = 2VF IOUTTNOL FS
where
TNOL = non-overlap time between GH and GL.
VF = forward voltage of the Schottky diode.
LOOP COMPENSATION DESIGN
The open loop gain of the whole system can
be divided into the gain of the error amplifier,
PWM modulator, buck converter output stage,
and feedback resistor divider. In order to
crossover at the selected frequency FCO, the
gain of the error amplifier has to compensate
for the attenuation caused by the rest of the
loop at this frequency. The goal of loop
compensation is to manipulate loop frequency
response such that its gain crosses over 0db
at a slope of -20db/dec. The first step of
compensation design is to pick the loop
crossover frequency. High crossover frequency
is desirable for fast transient response, but
often jeopardizes the system stability.
Crossover frequency should be higher than the
ESR zero but less than 1/5 of the switching
frequency. The ESR zero is contributed by the
ESR associated with the output capacitors and
can be determined by:
f Z (ESR)
=
1
2πCOUT
RESR
The next step is to calculated the complex
conjugate poles contributed by the LC output
filter,
f P(LC )
=
2π
1
LC
When the output capacitors are of a Ceramic
Type, the SP6134CU Evaluation Board requires
a Type III compensation circuit to give a
phase boost of 180° in order to counteract the
effects of an under damped resonance of the
output filter at the double pole frequency.
© 2008 Exar Corporation
11/15
Rev. 2.0.0
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet SP6134.PDF ] | |
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