參數(shù)資料
型號(hào)： L7981ATR
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, DSO8
封裝： 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, HSOP-8
文件頁數(shù)： 10/44頁
文件大?。?/td> 1315K
代理商： L7981ATR
Application informations
L7981
18/44
Doc ID 15182 Rev 3
6.3
Output capacitor selection
The current in the capacitor has a triangular waveform which generates a voltage ripple
across it. This ripple is due to the capacitive component (charge or discharge of the output
capacitor) and the resistive component (due to the voltage drop across its ESR). So the
output capacitor has to be selected in order to have a voltage ripple compliant with the
application requirements.
The amount of the voltage ripple can be calculated starting from the current ripple obtained
by the inductor selection.
Equation 12
Usually the resistive component of the ripple is much higher than the capacitive one, if the
output capacitor adopted is not a multi layer ceramic capacitor (MLCC) with very low ESR
value.
The output capacitor is important also for loop stability: it fixes the double LC filter pole and
the zero due to its ESR. In Chapter 6.4, it will be illustrated how to consider its effect in the
system stability.
For example with VOUT=5 V, VIN=24 V, ΔIL=0.9 A (resulting by the inductor value), in order to
have a
ΔV
OUT=0.01VOUT, if the multi layer ceramic capacitor are adopted, 10uF are needed
and the ESR effect on the output voltage ripple can be neglected. In case of not negligible
ESR (electrolytic or tantalum capacitors), the capacitor is chosen taking into account its
ESR value. So in case of 330 F with ESR=30 m
Ω, the resistive component of the drop
dominates and the voltage ripple is 28 mV
.
The output capacitor is also important to sustain the output voltage when a load transient
with high slew rate is required by the load. When the load transient slew rate exceeds the
system bandwidth the output capacitor provides the current to the load. So if the high slew
rate load transient is required by the application the output capacitor and system bandwidth
have to be chosen in order to sustain the load transient.
In the table below some capacitor series are listed.
Table 8.
Output capacitors
Manufacturer
Series
Cap value (
μF)
Rated voltage (V)
ESR (m
Ω)
MURATA
GRM32
22 to 100
6.3 to 25
< 5
GRM31
10 to 47
6.3 to 25
< 5
PANASONIC
ECJ
10 to 22
6.3
< 5
EEFCD
10 to 68
6.3
15 to 55
SANYO
TPA/B/C
100 to 470
4 to 16
40 to 80
TDK
C3225
22 to 100
6.3
< 5
ΔV
OUT
ESR
ΔI
MAX
ΔI
MAX
8C
OUT
f
SW
-------------------------------------
+
=
相關(guān)PDF資料
PDF描述
L7981TR SWITCHING REGULATOR, DSO8
L8219LP STEPPER MOTOR CONTROLLER, 2.5 A, PDSO28
L8219P STEPPER MOTOR CONTROLLER, 2.5 A, PDSO36
L8229 STEPPER MOTOR CONTROLLER, 1.5 A, PDSO24
L9484 SWITCHING REGULATOR, 460 kHz SWITCHING FREQ-MAX, PSFM8
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L7981ATR/BLK 制造商:STMicroelectronics 功能描述:3 A STEP-DOWN SWITCHING REGULATO - Tape and Reel 制造商:STMicroelectronics 功能描述:STMicroelectronics L7981ATR/BLK Interface Misc
L7981TR 功能描述:直流/直流開關(guān)調(diào)節(jié)器 3A DC 4.5 V to 28 V Adj 0.6V 250 kHz RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
L7983 制造商:Leviton Manufacturing Co 功能描述:
L7985 功能描述:線性穩(wěn)壓器 - 標(biāo)準(zhǔn) 2A Step Down REG 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 輸出類型: 極性: 輸出電壓:1.8 V 輸出電流:150 mA 負(fù)載調(diào)節(jié): 最大輸入電壓:5.5 V 線路調(diào)整率: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-323-5L
L7985A 功能描述:直流/直流開關(guān)調(diào)節(jié)器 2A DC 4.5V to 38V 250 KHz Step-Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購

我的聯(lián)系方式

*
*
*