參數(shù)資料
型號(hào): LM2596T-12
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 穩(wěn)壓器
英文描述: SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator
中文描述: 7.5 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, PZFM5
封裝: BENT STAGGERED, TO-220, 5 PIN
文件頁(yè)數(shù): 14/31頁(yè)
文件大小: 736K
代理商: LM2596T-12
LM2596 Series Buck Regulator Design Procedure (Adjustable Output)
(Continued)
PROCEDURE (Adjustable Output Voltage Version)
EXAMPLE (Adjustable Output Voltage Version)
3. Output Capacitor Selection (C
OUT
)
A.
In the majority of applications, low ESR electrolytic or solid
tantalum capacitors between 82 μF and 820 μF provide the
best results. This capacitor should be located close to the IC
using short capacitor leads and short copper traces. Do not
use capacitors larger than 820 μF.
For additional informa-
tion, see section on output capacitors in application in-
formation section.
B.
To simplify the capacitor selection procedure, refer to the
quick design table shown in Figure 3 This table contains
different output voltages, and lists various output capacitors
that will provide the best design solutions.
C.
The capacitor voltage rating should be at least 1.5 times
greater than the output voltage, and often much higher voltage
ratings are needed to satisfy the low ESR requirements
needed for low output ripple voltage.
3. Output Capacitor SeIection (C
OUT
)
A.
See section on C
OUT
in Application Information section.
B.
From the quick design table shown in Figure 3 locate the
output voltage column. From that column, locate the output
voltage closest to the output voltage in your application. In this
example, select the 24V line. Under the output capacitor sec-
tion, select a capacitor from the list of through hole electrolytic
or surface mount tantalum types from four different capacitor
manufacturers. It is recommended that both the manufactur-
ers and the manufacturers series that are listed in the table be
used.
In this example, through hole aluminum electrolytic capacitors
from several different manufacturers are available.
220 μF/35V Panasonic HFQ Series
150 μF/35V Nichicon PL Series
C.
For a 20V output, a capacitor rating of at least 30V or more
is needed. In this example, either a 35V or 50V capacitor
would work. A 35V rating was chosen, although a 50V rating
could also be used if a lower output ripple voltage is needed.
Other manufacturers or other types of capacitors may also be
used, provided the capacitor specifications (especially the 100
kHz ESR) closely match the types listed in the table. Refer to
the capacitor manufacturers data sheet for this information.
4. Feedforward Capacitor (C
FF
)
(See Figure 1)
For output voltages greater than approximately 10V, an addi-
tional capacitor is required. The compensation capacitor is
typically between 100 pF and 33 nF, and is wired in parallel
with the output voltage setting resistor, R
. It provides addi-
tional stability for high output voltages, low input-output volt-
ages, and/or very low ESR output capacitors, such as solid
tantalum capacitors.
This capacitor type can be ceramic, plastic, silver mica, etc.
(Because of the unstable characteristics of ceramic capacitors
made with Z5U material, they are not recommended.)
4. Feedforward Capacitor (C
FF
)
The table shown in Figure 3 contains feed forward capacitor
values for various output voltages. In this example, a 560 pF
capacitor is needed.
L
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參數(shù)描述
LM2596T12 制造商:Texas Instruments 功能描述:SWITCHING REG 3A 12V 2596 TO2205
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