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Número de pieza | SD45215 | |
Descripción | HIGH EFFICIENCY STEP-DOWN DC/DC CONVERTER | |
Fabricantes | SILAN | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de SD45215 (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
No Preview Available ! SD45215_Datasheet
HIGH EFFICIENCY STEP-DOWN DC/DC CONVERTER WITH
ADJUSTABLE CURRENT LIMIT FOR AUTOMOTIVE APPLICATIONS
DESCRIPTION
The SD45215 is a high efficiency step down DC-DC converter with
adjustable current limit in compact SOP-8 package, including an
error amplifier, ramp generator, current comparator, slope
compensation, current sense and logic driver. It also integrates a
current error amplifier to have a constant voltage and constant
current control.
Peak current mode PWM control with external adjustable
compensation provides a stable and high efficient operation over a
SOP-8-225-1.27
wide range of load currents. By means of an on board current sense
resistor and the availability of the current sense pins, a current limit
programming is very simple and accurate.
The internal robust PMOS transistor with a typical of 150 mΩ
assures high efficiency even at high output current level. The internal
limiting current of typical value of 3 A, output short and over APPLICATIONS
temperature protection, protect the device from accidental damage.
The internal fixed switching frequency of 120 kHz, and the SOP-8 * Automotive applications
package pin allow building an ultra compact DC/ DC converter with a * Chargers for NiCd, NiMH batteries
minimum board space.
* Simple step-down converters with
FEATURES
adjustable current limit
* Adjustable current generator
* Up to 1.5A output current
* Up to 90% Efficiency
* Input Voltage Range: 8V to 30V
* 120 kHz Internal Jitter Frequency for lower EMI
* Patent -Pending Short Circuit Protection
* Patent -Pending Output Voltage Compensation
* Adjustable current limit
* Over Temperature Protection
* Small SOP-8 Package
ORDERING INFORMATION
Part No.
SD45215SA
SD45215SATR
Package
SOP-8-225-1.27
SOP-8-225-1.27
Marking
45215SA
45215SA
Material
Pb free
Pb free
Packing
Tube
Tape&Reel
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http://www.silan.com.cn
REV:1.3
2011.04.21
Page 1 of 8
Free Datasheet http://www.Datasheet4U.com
1 page SD45215_Datasheet
APPLICATIONS INFORMATION
Output Voltage And Feedback Loop Settings
Refer to the figure1, the output voltage of the switching regulator (VOUT) can be set with Equation following:
R3
VOUT = (1 + )X0.835V
R4
The limit current is set by the external resistor R2:
75mV
ILIMIT =
R2
The SD45215 uses a patent-pending output voltage compensation scheme for the conductor wire loss by properly
selecting the value of R3、R4, if the conductor resistance is Rline, current sense resistor is R2 (Refer to the
figure1), then:
Rline
R3 =
160μ ⋅ R2
0.835 ⋅ R3
R4 =
VOUT - 0.835
For Rline=80mΩ, R2=50mΩ (1.5A current limit as figure 1), VOUT=5V; R3=10k, R4=2k, as the figure1.
Component Selection
Inductor Selection
The SD45215 can utilize small inductors due to its fast 120kHz switching frequency. Typically, a 100μH inductor is
recommended for most applications. Larger values of inductance will allow greater output current capability by
reducing the inductor ripple current. Increasing the inductance above will also increase size.
The inductor current ripple is typically set for 20% to 40% of the maximum inductor current (IP). The inductor should
have low ESR (series resistance of the windings) to reduce the power losses, and must be able to handle the peak
inductor current without saturating. To minimize radiated noise, use a shielded bobbin inductor.
Output and Input Capacitor Selection
Low ESR (equivalent series resistance) capacitors should be used to minimize the output voltage ripple. The parallel
of multilayer ceramic and electrolytic capacitors is an excellent choice as they have extremely low ESR and are low
cost. A parallel of 10μF ceramic capacitor and 470μF electrolytic capacitor is sufficient for most applications. Larger
values may be used to obtain extremely low output voltage ripple and improve transient response.
Low ESR input capacitors reduce input switching noise and reduce the peak current drawn from the battery. It
follows that ceramic capacitors are also a good choice for input decoupling, and should be located as close as
possible to the device. A 10μF input capacitor is sufficient for virtually any application.
For all the ceramic capacitors above, X5R and X7R dielectric materials are preferred, for their ability to maintain
capacitance over wide voltage and temperature ranges.
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
Http://www.silan.com.cn
REV:1.3
2011.04.21
Page 5 of 8
Free Datasheet http://www.Datasheet4U.com
5 Page |
Páginas | Total 8 Páginas | |
PDF Descargar | [ Datasheet SD45215.PDF ] |
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