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Número de pieza | AX3122 | |
Descripción | 5A Synchronous buck Converter | |
Fabricantes | AXElite | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de AX3122 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
No Preview Available ! AX3122
5A Synchronous buck Converter
GENERAL DESCRIPTION
AX3122 consists of step-down switching regulator with synchronous PWM converter.
These devise include a reference voltage source, oscillation circuit, error amplifier, internal
PMOS and external NMOS etc.
AX3122 provides 5A high current, low-ripple power, high efficiency, and excellent
transient characteristics. The PWM control circuit is able to the duty ratio linearly form 0 up
to 100%. An over current protect function and short circuit protect function are built inside,
and when OCP or SCP happens, the operation frequency will be reduced. Also, an external
compensation is easily to system stable.
With the addition of internal PMOS, external NMOS, a coil and capacitors externally,
these ICs can function as step-down switching regulators. The device serve 5A high power
supply system, the external NMOS can reduce IC temperature and promote system
efficiency for heavy load. Since this converter can accommodate an input voltage up to
23V.
FEATURES
- Input voltage:4.5V to 23V
- Output voltage:VFB to VCC
- Duty ratio:0% to 100% PWM control
- Oscillation frequency:250KHz typ.
- Current Limit (CL).
- Thermal Shutdown function.
- Short Circuit Protect (SCP).
- Built-in internal P-channel MOS and drive external N-channel MOS.
- SOP-8L with Exposed Pad Pb-Free package.
1/9
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.2 Aug.19, 2010
1 page AX3122
Table 1 Resistor select for output voltage setting
VOUT
R4
R2
5.0V 4.7K 33K
3.3V 3K 13K
2.5V 3.3K 10K
1.8V 6.8K 13K
1.5V
1.184V
1.0V
3.3K
3.3K
3.3K
4.7K
3.0K
2.0K
COMP
Compensation pin. The COMP pin connects R3 and C8 to GND for all condition. In
Low ESR output capacitor, R3=1.2KΩ and C8=10nF. When ESR>80mΩ, R3 can be
changed to 820Ω. Please refer the application circuit table.
Inductor Selection
For most designs, the inductor is suggested 22µH to 33µH. Please refer the below
table to design.
VOUT
L1 Value
L1 recommend value (VIN=12V ,IOUT=5A)
1.2V 1.8V 2.5V 3.3V
22uH
22H
22uH
33uH
5V
33uH
Where is inductor Ripple Current. Large value inductors lower ripple current and
small value inductors result in high ripple currents. Choose inductor ripple current
approximately 15% of the maximum load current 5A, ΔIL=0.75A. The DC current rating of
the inductor should be at least equal to the maximum load current plus half the ripple
current to prevent core saturation (5A+0.375A).
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching
noise from the device. The input capacitor impedance at the switching frequency shall be
less than input source impedance to prevent high frequency switching current passing to
the input. A low ESR input capacitor sized for maximum RMS current must be used.
The capacitor voltage rating should be at least 1.5 times greater than the input
voltage, and often much higher voltage ratings are needed to satisfy.
5/9
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.2 Aug.19, 2010
5 Page |
Páginas | Total 9 Páginas | |
PDF Descargar | [ Datasheet AX3122.PDF ] |
Número de pieza | Descripción | Fabricantes |
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AX3122 | 5A Synchronous buck Converter | AXElite |
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