參數(shù)資料
型號(hào)： LT1578
廠商： Linear Technology Corporation
英文描述： 1.5A, 200kHz Step-Down Switching Regulator(1.5A, 200kHz，步降開(kāi)關(guān)穩(wěn)壓器)
中文描述： 1.5A的，200kHz降壓型開(kāi)關(guān)穩(wěn)壓器（1.5A的，200kHz的，步降開(kāi)關(guān)穩(wěn)壓器）
文件頁(yè)數(shù)： 12/28頁(yè)
文件大?。?/td> 292K
代理商： LT1578
12
LT1578/LT1578-2.5
APPLICATIO
S I
N
FOR
ATIO
U
Output Capacitor
The output capacitor is normally chosen by its Effective
Series Resistance (ESR), because this is what determines
output ripple voltage. To get low ESR takes volume so
physically smaller capacitors have high ESR. The ESR
range for typical LT1578 applications is 0.05
to 0.2
. A
typical output capacitor is an AVX type TPS, 100
μ
F at 10V,
with a guaranteed ESR less than 0.1
. This is a “D” size
surface mount solid tantalum capacitor. TPS capacitors
are specially constructed and tested for low ESR, so they
give the lowest ESR for a given volume. The value in
microfarads is not particularly critical, and values from
22
μ
F to greater than 500
μ
F work well, but you cannot
cheat mother nature on ESR. If you find a tiny 22
μ
F solid
tantalum capacitor, it will have high ESR, and output ripple
voltage will be terrible. Table 2 shows some typical solid
tantalum surface mount capacitors.
W
U
Output Capacitor Ripple Current (RMS):
I
V
V
V
L f V
( )( )( )
RIPPLE RMS
OUT
IN
OUT
IN
)
=
(
)
(
)
0 29
Ceramic Capacitors
Higher value, lower cost ceramic capacitors are now
becoming available in smaller case sizes. These are tempt-
ing for switching regulator use because of their very low
ESR. Unfortunately, the ESR is so low that it can cause
loop stability problems. Solid tantalum capacitor’s ESR
generates a loop “zero” at 5kHz to 50kHz that is instrumen-
tal in giving acceptable loop phase margin. Ceramic
capacitors remain capacitive to beyond 300kHz and usu-
ally resonate with their ESL before their ESR provides any
damping. They are appropriate for input bypassing be-
cause of their high ripple current ratings and tolerance of
turn-on surges.
OUTPUT RIPPLE VOLTAGE
Figure 3 shows a typical output ripple voltage waveform
for the LT1578. Ripple voltage is determined by the high
frequency impedance of the output capacitor, and ripple
current through the inductor. Peak-to-peak ripple current
through the inductor into the output capacitor is:
)
( )( )( )
I
V
V
V
V
L f
P
OUT
IN
OUT
IN
-P
=
(
(
)
For high frequency switchers, the sum of ripple current
slew rates may also be relevant and can be calculated
from:
Σ
dI
dt
V
L
IN
=
Table 2. Surface Mount Solid Tantalum Capacitor ESR
and Ripple Current
E Case Size
AVX TPS, Sprague 593D
AVX TAJ
D Case Size
AVX TPS, Sprague 593D
C Case Size
AVX TPS
ESR (Max.,
)
0.1 to 0.3
0.7 to 0.9
Ripple Current (A)
0.7 to 1.1
0.4
0.1 to 0.3
0.7 to 1.1
0.2 (typ)
0.5 (typ)
Many engineers have heard that solid tantalum capacitors
are prone to failure if they undergo high surge currents.
This is historically true, and type TPS capacitors are
specially tested for surge capability, but surge ruggedness
is not a critical issue with the outputcapacitor. Solid
tantalum capacitors fail during very high turn-onsurges,
which do not occur at the output of regulators. High
dischargesurges, such as when the regulator output is
dead shorted, do not harm the capacitors.
Unlike the input capacitor, RMS ripple current in the
output capacitor is normally low enough that ripple cur-
rent rating is not an issue. The current waveform is
triangular with a typical value of 200mA
RMS
. The formula
to calculate this is:
相關(guān)PDF資料
PDF描述
LT1579CS CAP 47UF 63V ELECT TG SMD
LT1579CS-5 300mA Dual Input Smart Battery Backup Regulator
LT1579CS-3 300mA Dual Input Smart Battery Backup Regulator
LT1579CS-3.3 300mA Dual Input Smart Battery Backup Regulator
LT1579CS8 CAP 22UF 80V ELECT TG SMD
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT1578-2.5 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:1.5A, 200kHz Step-Down Switching Regulator
LT1578C 制造商:LINER 制造商全稱(chēng):Linear Technology 功能描述:1.5A, 200kHz Step-Down Switching Regulator
LT1578CS8 功能描述:IC REG BUCK ADJ 1.5A 8SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤(pán) 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤(pán)
LT1578CS8#PBF 功能描述:IC REG BUCK ADJ 1.5A 8SOIC RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤(pán) 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤(pán)
LT1578CS8#TR 功能描述:IC REG BUCK ADJ 1.5A 8SOIC RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開(kāi)關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類(lèi)型:降壓（降壓） 輸出類(lèi)型:固定 輸出數(shù):1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開(kāi)關(guān):- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類(lèi)型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤(pán) 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:10-MSOP 裸露焊盤(pán)
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。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(gòu)。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(gòu)

我的聯(lián)系方式

*
*
*