AS5430 Datasheet PDF - A1semi
Part Number | AS5430 | |
Description | 3A 400KHz Synchronous Rectified Step-Down Converter | |
Manufacturers | A1semi | |
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A1semi
Electronics Ltd
AS54303A 400KHz Synchronous Rectified
Step-Down Converter
GENERAL DESCRIPTION
The AS5430 is a monolithic synchronous buck regulator.
The device integrates 100mΩ MOSFETS that
provide 3A continuous load current over a wide
operating input voltage of 4.75V to 23V. Current
mode control provides fast transient response
and cycle-by-cycle current limit.
An adjustable soft-start prevents inrush current at
turn-on. In shutdown mode, the supply current
drops below 1uA. The device provides a very
compact system solution with minimal reliance on
external components.
FEATURES
3A Output Current
Integrated 100mΩ Power MOSFETS
Wide 4.75~23V Input Voltage Range
Programmable Soft-start
Up to 95% Efficiency
Stable with Low ESR Ceramic Output Capacitors
Output Adjustable From 0.925V to 20V
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Fixed 400KHz Frequency
APPLICATION
Distribute Power Supply
Networking Systems
Notebook or Mini-book
LCD TV/LCD Monitor
ORDER INFORMATION
Order Number
AS5430D/TR-LF
Package
SOP8(Exposed Pad)
BLOCK DIAGRAM
Packing
Tape&Reel, MPQ=2500
Remark
Lead-Free
AS5430Ver1.0
1 http://www.a1semi.com
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A1
A1semi
Electronics Ltd
AS54303A 400KHz Synchronous Rectified
Step-Down Converter
DETAILED DESCRIPTION
Functional Description
The AS5430 is a synchronous rectified, current -
mode, step-down regulator.It regulates input
voltage from 4.75V to 23V down to an output
voltage as low as 0.925V,and supplies up to 3A of
load current.
The AS5430 uses current-mode control to regulate
the output voltage.The output voltage is measured
at FB through a resistive voltage divider and
amplified through the internal transconductance
error amplifier.The voltage at the COMP pin is
compared to the switch current measured
internally to control the output voltage.
Application Information
COMPONENT SELECTION
Setting the Output Voltage
The output voltage is set using a resistive voltage
divider from the output voltage to FB.The voltage
divider the output voltage down by the radio:
Where VFB is the feedback voltage and VOUT is the
output voltage. Thus the output voltage is:
R2 can be as high as 100kΩ,but a typical value is
10kΩ.Using the typical value for R2,R1 is
determined by:
The converter uses internal N-Channel MOSFET
switches to step-down the input voltage to the
regulated output voltage.Since the high side
MOSFET requires a gate voltage greater than the
input voltage,a boost capacitor connected
between SW and BS is needed to drive the high
side gate. The boost capacitor is charged from the
internal 5V rail when SW is low.
When the AS5430 FB pin exceeds 20% of the
nominal regulation voltage of 0.925V,the over
voltage comparator is tripped and the COMP pin
and the SS pin are discharged to GND,forcing the
high-side switch off.
INDUCTOR
The inductor is required to supply constant current to
the output load while being driven by the switched
input voltage. A larger value inductor will result in less
ripple current that will result in lower output ripple
voltage. However, the larger value inductor will have
a larger physical size, higher series resistance, and/or
lower saturation current. A good rule for determining
the inductance to use is to allow the peak-to-peak
ripple current in the inductor to be approximately 30%
of the maximum switch current limit. Also,make sure
that the peak inductor current is below the maximum
switch current limit. The inductance value can be
calculated by:
For example,for a 3.3V output voltage,R2 is 10kΩ,
and R1 is 26.1kΩ.Table 1 lists recommended
Resistance values of R1 and R2 for standard output
voltage
Table1--Recommended Resistance Values
Vout R1( kΩ) R2( kΩ)
1.8V
2.5V
3.3V
5V
12V
9.53
16.9
26.1
44.2
121
10
10
10
10
10
Where VOUT is the output voltage, VIN is the input
voltage, fs is the switching frequency, and ΔIL is the
peak-to-peak inductor ripple current.
Choose an inductor that will not saturate under the
maximum inductor peak current. The peak inductor
current can be calculated by:
Where ILOAD is the load current. The choice of which
style inductor to use mainly depends on the price
vs.size requirements and any EMI requirements.
AS5430Ver1.0
5 http://www.a1semi.com
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for AS5430 electronic component. |
Information | Total 9 Pages | |
Link URL | [ Copy URL to Clipboard ] | |
Download | [ AS5430.PDF Datasheet ] |
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