參數(shù)資料
型號(hào)： LTC1957-1EMS8
英文描述： AMP POWER CONTROLLER
中文描述： 安培電源控制器
文件頁(yè)數(shù)： 12/28頁(yè)
文件大小： 389K
代理商： LTC1957-1EMS8
LTC1929/LTC1929-PG
APPLICATIU
When using the controller in very low dropout conditions,
the maximum output current level will be reduced due to
internal compensation required to meet stability criterion
for buck regulators operating at greater than 50% duty
factor. A curve is provided to estimate this reduction in
peak output current level depending upon the operating
duty factor.
W
U
U
Operating Frequency
The LTC1929 uses a constant frequency, phase-lockable
architecture with the frequency determined by an internal
capacitor. This capacitor is charged by a fixed current plus
an additional current which is proportional to the voltage
applied to the PLLFLTR pin. Refer to Phase-Locked Loop
and Frequency Synchronization in the Applications Infor-
mation section for additional information.
A graph for the voltage applied to the PLLFLTR pin vs
frequency is given in Figure2. As the operating frequency
is increased the gate charge losses will be higher, reducing
efficiency (see Efficiency Considerations). The maximum
switching frequency is approximately 310kHz.
MOSFET gate charge and transition losses. In addition to
this basic tradeoff, the effect of inductor value on ripple
current and low current operation must also be considered.
The PolyPhase approach reduces both input and output
ripple currents while optimizing individual output stages to
run at a lower fundamental frequency, enhancing efficiency.
The inductor value has a direct effect on ripple current. The
inductor ripple current
I
L
per individual section, N,
decreases with higher inductance or frequency and in-
creases with higher V
IN
or V
OUT
:
I
V
fL
V
V
L
OUT
OUT
IN
=
1
where f is the individual output stage operating frequency.
In a 2-phase converter, the net ripple current seen by the
output capacitor is much smaller than the individual
inductor ripple currents due to the ripple cancellation. The
details on how to calculate the net output ripple current
can be found in Application Note 77.
Figure 3 shows the net ripple current seen by the output
capacitors for the 1- and 2-phase configurations. The
output ripple current is plotted for a fixed output voltage as
the duty factor is varied between 10% and 90% on the
x-axis. The output ripple current is normalized against the
inductor ripple current at zero duty factor. The graph can
be used in place of tedious calculations, simplifying the
design process.
Figure 2. Operating Frequency vs V
PLLFLTR
Figure 3. Normalized Output Ripple Current
vs Duty Factor [I
RMS
≈
0.3 (
I
O(P–P)
)]
OPERATING FREQUENCY (kHz)
120
170
220
270
320
P
1929 F02
2.5
2.0
1.5
1.0
0.5
0
Inductor Value Calculation and Output Ripple Current
The operating frequency and inductor selection are inter-
related in that higher operating frequencies allow the use
of smaller inductor and capacitor values. So why would
anyone ever choose to operate at lower frequencies with
larger components The answer is efficiency. A higher
frequency generally results in lower efficiency because of
DUTY FACTOR (V
OUT
/V
IN
)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1929 F03
2-PHASE
1-PHASE
I
O
V
O
/
Powered by ICminer.com Electronic-Library Service CopyRight 2003
相關(guān)PDF資料
PDF描述
LTC1957-2EMS AMP POWER CONTROLLER
LTC25501PAK Optoelectronic
LTC25601PAK Optoelectronic
LTC3405AES6 Analog IC
LTC5502A1P12 Optoelectronic
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1957-1EMS8#PBF 功能描述:IC RF PWR CONTRLLR SINGLE 8-MSOP RoHS:是 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點(diǎn):四頻帶 封裝/外殼:8-VFBGA 供應(yīng)商設(shè)備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX
LTC1957-1EMS8#TR 功能描述:IC RF PWR CONTRLLR SINGLE 8-MSOP RoHS:否 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點(diǎn):四頻帶 封裝/外殼:8-VFBGA 供應(yīng)商設(shè)備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX
LTC1957-1EMS8#TRPBF 功能描述:IC RF PWR CONTRLLR SINGLE 8-MSOP RoHS:是 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點(diǎn):四頻帶 封裝/外殼:8-VFBGA 供應(yīng)商設(shè)備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX
LTC1957-2EMS 功能描述:IC RF PWR CONTROLLR DUAL 10-MSOP RoHS:否 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點(diǎn):四頻帶 封裝/外殼:8-VFBGA 供應(yīng)商設(shè)備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX
LTC1957-2EMS#PBF 功能描述:IC RF PWR CONTROLLR DUAL 10-MSOP RoHS:是 類別:RF/IF 和 RFID >> RF 電源控制器 IC 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- RF 型:GSM 頻率:450MHz ~ 2GHz 特點(diǎn):四頻帶 封裝/外殼:8-VFBGA 供應(yīng)商設(shè)備封裝:8-MicroSMD（1.51x1.51） 包裝:帶卷 (TR) 其它名稱:LMV243BLX
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

*
*
*