參數(shù)資料
型號(hào)： LT1307BCS8
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： Single Cell Micropower 600kHz PWM DC/DC Converters
中文描述： 1.25 A SWITCHING REGULATOR, 750 kHz SWITCHING FREQ-MAX, PDSO8
封裝： 0.150 INCH, PLASTIC, SO-8
文件頁(yè)數(shù)： 10/20頁(yè)
文件大?。?/td> 377K
代理商： LT1307BCS8
10
LT1307/LT1307B
APPLICATIO
S I
FOR
ATIO
U
W
U
U
To eliminate the low frequency noise of Figure 6, the
LT1307 can be replaced with the LT1307B. Figure 9
details the spectral noise at the output of Figure 1’s circuit
using an LT1307B at 5mA load. Although spectral energy
is present at 333kHz due to alternate pulse skipping, all
Burst Mode operation spectral components are gone.
Alternate pulse skipping can be eliminated by increasing
inductance.
FREQUENCY COMPENSATION
Obtaining proper values for the frequency compensation
network is largely an empirical, iterative procedure, since
variations in input and output voltage, topology, capacitor
value and ESR, and inductance make a simple formula
elusive. As an example, consider the case of a 1.25V to
3.3V boost converter supplying 50mA. To determine
optimum compensation, the circuit is built and a transient
load is applied to the circuit. Figure 10 shows the setup.
away from 455kHz.
Figure 8 shows the noise spectrum of
the converter with the load increased to 20mA. The
LT1307 shifts out of Burst Mode operation, eliminating
low frequency ripple. Spectral energy is present only at
the switching fundamental and its harmonics. Noise
voltage measures –5dBmV
RMS
or 560
μ
V
RMS
at the
575kHz switching frequency, and is below –60dBmV
RMS
for all other frequencies in the range. By combining Burst
Mode with fixed frequency operation, the LT1307 keeps
noise away from 455kHz.
10
μ
H
MBR0520L
1307 F10
590k
1M
3300
R
1
μ
F
1.25V
10
μ
F*
C
66
V
OUT
50
*CERAMIC
V
IN
SHDN
SW
LT1307
FB
V
C
GND
Figure 10. Boost Converter with Simulated Load
Figure 11a details transient response without compensa-
tion components. Although the output ripple voltage at a
1mA load is low, allowing the error amplifier to operate
wideband results in excessive ripple at a 50mA load. Some
kind of loop stabilizing network is obviously required. A
100k/22nF series RC is connected to the V
C
pin, resulting
in the response pictured in Figure 11b. The output settles
in about 7ms to 8ms. This may be acceptable, but we can
do better. Reducing C to 2nF gives Figure 11c’s response.
This is clearly in the right direction. After another order of
magnitude reduction, Figure 11d’s response shows some
FREQUENCY (kHz)
205
O
R
)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
LT1307 F09
455
705
Figure 9. LT1307B at 5mA Load Shows No Audio Components
or Sidebands About Switching Frequency, 333kHz
Fundamental Amplitude is –10dBmV, or 316
μ
V
RMS
FREQUENCY (kHz)
255
O
R
)
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
455
1307 F08
655
RBW = 100Hz
Figure 8. With Converter Delivering 20mA, Low Frequency
Sidebands Disappear. Noise is Present Only at the 575kHz
Switching Frequency
相關(guān)PDF資料
PDF描述
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LT1307BCS8#PBF 功能描述:IC REG BOOST 3.3V/5V 0.1A 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關(guān):2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:6-SON（1.45x1） 產(chǎn)品目錄頁(yè)面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2
LT1307BCS8#TR 功能描述:IC REG BOOST 3.3V/5V 0.1A 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC
LT1307BCS8#TRPBF 功能描述:IC REG BOOST 3.3V/5V 0.1A 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC
LT1307BCS8PBF 制造商:Linear Technology 功能描述:DC-DC 1-Cell Micropower 600kHz PWM SOIC8
LT1307BIS8 功能描述:IC REG BOOST 3.3V/5V 0.1A 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關(guān)穩(wěn)壓器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調(diào)式 輸出數(shù):1 輸出電壓:1.24 V ~ 30 V 輸入電壓:1.5 V ~ 12 V PWM 型:電流模式，混合 頻率 - 開關(guān):600kHz 電流 - 輸出:500mA 同步整流器:無 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) 供應(yīng)商設(shè)備封裝:8-SOIC
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