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參數(shù)資料
| 型號： | LM3524DN |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Regulating Pulse Width Modulator |
| 中文描述： | 0.2 A SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDIP16 |
| 封裝： | PLASTIC, DIP-16 |
| 文件頁數(shù)： | 14/22頁 |
| 文件大小： | 1172K |
| 代理商： | LM3524DN |
Typical Applications
(Continued)
where: L1 is in Henrys
f is switching frequency in Hz
Also, see LM1578 data sheet for graphical methods of in-
ductor selection.
CALCULATING OUTPUT FILTER CAPACITOR C
o
:
Figure 13
shows L1’s current with respect to Q1’s t
and
t
times (V
is at the collector of Q1). This curent must
flow to the load and C
o
. C
o
’s current will then be the differ-
ence between I
L
, and I
o
.
Ic
o
= I
L
I
o
From
Figure 13
it can be seen that current will be flowing into
C
o
for the second half of t
ON
through the first half of t
OFF
, or
a time, t
ON
/2 + t
OFF
/2. The current flowing for this time is
I
L
/4. The resulting
V
c
or
V
o
is described by:
For best regulation, the inductor’s current cannot be allowed
to fall to zero. Some minimum load current I
o
, and thus
inductor current, is required as shown below:
A complete step-down switching regulator schematic, using
the LM3524D, is illustrated in
Figure 15
. Transistors Q1 and
Q2 have been added to boost the output to 1A. The 5V
regulator of the LM3524D has been divided in half to bias the
error amplifier’s non-inverting input to within its common-
mode range. Since each output transistor is on for half the
period, actually 45%, they have been paralleled to allow
longer possible duty cycle, up to 90%. This makes a lower
possible input voltage. The output voltage is set by:
where V
NI
is the voltage at the error amplifier’s non-inverting
input.
Resistor R3 sets the current limit to:
Figures 16, 17
and show a PC board layout and stuffing
diagram for the 5V, 1Aregulator of
Figure 15
. The regulator’s
performance is listed in
Table 1
.
00865019
FIGURE 14. Inductor Current Slope in Step-Down
Regulator
L
www.national.com
14
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM3524DN | 制造商:Texas Instruments 功能描述:ENHANCED PWM CONTROLLER 3524 DIP |
| LM3524DN/NOPB | 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓撲結(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| LM3524J | 制造商:OC White Company 功能描述:VOLT-MODE PWM CTRLR 16-Pin CDIP Rail |
| LM3524J/A+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Voltage-Mode SMPS Controller |
| LM3524M | 制造商:Texas Instruments 功能描述: |
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