參數(shù)資料
型號(hào)： LM3524DMWC
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 0.2 A SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, UUC
封裝： WAFER
文件頁(yè)數(shù)： 3/22頁(yè)
文件大?。?/td> 728K
代理商： LM3524DMWC
Typical Applications (Continued)
Neglecting V
SAT,VD, and settling IL
+ =
I
L
;
where T = Total Period
The above shows the relation between V
IN,Vo and duty
cycle.
as Q1 only conducts during t
ON.
The efficiency,
η, of the circuit is:
ηMAX will be further decreased due to switching losses in
Q1. For this reason Q1 should be selected to have the maxi-
mum possible f
T, which implies very fast rise and fall times.
CALCULATING INDUCTOR L1
Since
I
L+ = IL
= 0.4I
o
Solving the above for L1
where: L1 is in Henrys
f is switching frequency in Hz
Also, see LM1578 data sheet for graphical methods of induc-
tor selection.
CALCULATING OUTPUT FILTER CAPACITOR C
o:
Figure 13 shows L1’s current with respect to Q1’s t
ON and
t
OFF times (VA is at the collector of Q1). This curent must
flow to the load and C
o.Co’s current will then be the differ-
ence between I
L, and Io.
Ic
o = IL Io
From
Figure 13 it can be seen that current will be flowing into
C
o for the second half of tON through the first half of tOFF,or
a time, t
ON/2+tOFF/2. The current flowing for this time is
I
L/4. The resulting Vc or Vo 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 in-
ductor current, is required as shown below:
DS008650-17
FIGURE 13. Relation of Switch Timing to Inductor Current in Step-Down Regulator
www.national.com
11
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM3524DMX 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?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)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
LM3524DMX/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?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)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
LM3524DN 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?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)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
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?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開(kāi)關(guān)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
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