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| 型号： | LM2577MX-12/NOPB |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 6 A SWITCHING REGULATOR, 62 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封装： | 0.300 INCH, SO-24 |
| 文件页数： | 8/34页 |
| 文件大小： | 1008K |
| 代理商： | LM2577MX-12/NOPB |
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Application Hints (Continued)
2. Compensation Network (R
C,CC) and Output Capacitor
(C
OUT) Selection
R
C and CC form a pole-zero compensation network that sta-
bilizes the regulator. The values of R
C and CC are mainly de-
pendant on the regulator voltage gain, I
LOAD(max), L and
C
OUT. The following procedure calculates values for RC,CC,
and C
OUT that ensure regulator stability. Be aware that this
procedure doesn’t necessarily result in R
C and CC that pro-
vide optimum compensation. In order to guarantee optimum
compensation, one of the standard procedures for testing
loop stability must be used, such as measuring V
OUT tran-
sient response when pulsing I
LOAD (see Figure 15).
A.
First, calculate the maximum value for RC.
Select a resistor less than or equal to this value, and it
should also be no greater than 3 k
.
B.
Calculate the minimum value for C
OUT using the following
two equations.
The larger of these two values is the minimum value that en-
sures stability.
C.
Calculate the minimum value of CC .
The compensation capacitor is also part of the soft start cir-
cuitry. When power to the regulator is turned on, the switch
duty cycle is allowed to rise at a rate controlled by this ca-
pacitor (with no control on the duty cycle, it would immedi-
ately rise to 90%, drawing huge currents from the input
power supply). In order to operate properly, the soft start cir-
cuit requires C
C ≥ 0.22 F.
The value of the output filter capacitor is normally large
enough to require the use of aluminum electrolytic capaci-
tors.
Figure 11 lists several different types that are recom-
mended for switching regulators, and the following param-
eters are used to select the proper capacitor.
Working Voltage (WVDC): Choose a capacitor with a work-
ing voltage at least 20% higher than the regulator output volt-
age.
Ripple Current: This is the maximum RMS value of current
that charges the capacitor during each switching cycle. For
step-up and flyback regulators, the formula for ripple current
is
Choose a capacitor that is rated at least 50% higher than this
value at 52 kHz.
Equivalent Series Resistance (ESR) : This is the primary
cause of output ripple voltage, and it also affects the values
of R
C and CC needed to stabilize the regulator. As a result,
the preceding calculations for C
C and RC are only valid if
ESR doesn’t exceed the maximum value specified by the fol-
lowing equations.
Select a capacitor with ESR, at 52 kHz, that is less than or
equal to the lower value calculated. Most electrolytic capaci-
tors specify ESR at 120 Hz which is 15% to 30% higher than
at 52 kHz. Also, be aware that ESR increases by a factor of
2 when operating at 20C.
In general, low values of ESR are achieved by using large
value capacitors (C
≥ 470 F), and capacitors with high
WVDC, or by paralleling smaller-value capacitors.
Inductor
Manufacturer’s Part Number
Code
Schott
Pulse
Renco
L47
67126980
PE - 53112
RL2442
L68
67126990
PE - 92114
RL2443
L100
67127000
PE - 92108
RL2444
L150
67127010
PE - 53113
RL1954
L220
67127020
PE - 52626
RL1953
L330
67127030
PE - 52627
RL1952
L470
67127040
PE - 53114
RL1951
L680
67127050
PE - 52629
RL1950
H150
67127060
PE - 53115
RL2445
H220
67127070
PE - 53116
RL2446
H330
67127080
PE - 53117
RL2447
H470
67127090
PE - 53118
RL1961
H680
67127100
PE - 53119
RL1960
H1000
67127110
PE - 53120
RL1959
H1500
67127120
PE - 53121
RL1958
H2200
67127130
PE - 53122
RL2448
Schott Corp., (612) 475-1173
1000 Parkers Lake Rd., Wayzata, MN 55391
Pulse Engineering, (619) 268-2400
P.O. Box 12235, San Diego, CA 92112
Renco Electronics Inc., (516) 586-5566
60 Jeffryn Blvd. East, Deer Park, NY 11729
FIGURE 10. Table of Standardized Inductors and
Manufacturer’s Part Numbers
www.national.com
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM2577MX-15 | 功能描述:IC REG MULTI CONFIG 15V 24SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:SIMPLE SWITCHER® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| LM2577MX-ADJ | 功能描述:IC REG MULTI CONFIG ADJ 24SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:SIMPLE SWITCHER® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| LM2577N-12 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM2577N-12/NOPB | 功能描述:IC REG MULTI CONFIG 12V 3A 16DIP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:SIMPLE SWITCHER® 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:1 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:3.3V 输入电压:4.5 V ~ 24 V PWM 型:- 频率 - 开关:- 电流 - 输出:125mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 包装:Digi-Reel® 供应商设备封装:SOT-6 其它名称:MAX1836EUT33#TG16DKR |
| LM2577N-15 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:SIMPLE SWITCHER-R Step-Up Voltage Regulator |
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