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參數(shù)資料
| 型號： | LT1307IS8 |
| 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 |
| 文件頁數(shù)： | 9/20頁 |
| 文件大?。?/td> | 377K |
| 代理商： | LT1307IS8 |
9
LT1307/LT1307B
APPLICATIO
S I
FOR
ATIO
U
W
U
U
quite evident, as is this particular device’s 575kHz switch-
ing frequency (nominal switching frequency is 600kHz).
Note, however, the absence of significant energy at 455kHz.
Figure 7’s plot reduces the frequency span from 255kHz to
655kHz with a 455kHz center. Burst Mode low frequency
ripple creates sidebands around the 575kHz switching
fundamental. These sidebands have low signal amplitude
at 455kHz, measuring –55dBmV
RMS
. As load current is
further reduced, the Burst Mode frequency decreases.
This spaces the sidebands around the switching fre-
quency closer together, moving spectral energy further
Trace B. Similarly, Figure 4 details the two circuits with a
load step from 5mA to 45mA with a 1.5V input.
The LT1307B also can be used in lower current applica-
tions where a clean, low ripple output is needed. Figure 5
details transient response of a single cell to 3.3V con-
verter, using an inductor value of 100
μ
H. This high induc-
tance minimizes ripple current, allowing the LT1307B to
regulate without skipping cycles. As the load current is
stepped from 5mA to 10mA, the output voltage responds
cleanly. Note that the V
C
pin loop compensation has been
made more conservative (increased C, decreased R).
Figure 5. Increasing L to 100
μ
H, Along with R
C
= 36k,
C
C
= 20nF and C
OUT
= 10
μ
F, Low Noise Performance of
LT1307B Can Be Realized at Light Loads of 5mA to 10mA
10mA
5mA
I
L
V
IN
= 1.25V
V
OUT
= 3.3V
1ms/DIV
1307 F05
I
L
20mA/DIV
V
100mV/DIV
AC COUPLED
At light loads, the LT1307B will begin to skip alternate
cycles. The load point at which this occurs can be de-
creased by increasing the inductor value. However, output
ripple will continue to be significantly less than the LT1307
output ripple. Further, the LT1307B can be forced into
micropower mode, where I
Q
falls from 1mA to 50
μ
A by
pulling down V
C
to 0.3V or less externally.
DC/DC CONVERTER NOISE CONSIDERATIONS
Switching regulator noise is a significant concern in many
communications systems. The LT1307 is designed to
keep noise energy out of the sensitive 455kHz band at all
load levels while consuming only 60
μ
W to 100
μ
W at no
load. At light load levels, the device is in Burst Mode,
causing low frequency ripple to appear at the output.
Figure 6 details spectral noise directly at the output of
Figure 1’s circuit in a 1kHz to 1MHz bandwidth. The
converter supplies a 5mA load from a 1.25V input. The
Burst Mode fundamental at 5.1kHz and its harmonics are
FREQUENCY (kHz)
1
O
R
)
40
30
20
10
0
–10
–20
–30
–40
–50
–60
10
100
1000
1307 F06
RBW = 100Hz
Figure 6. Spectral Noise Plot of 3.3V Converter Delivering
5mA Load. Burst Mode Fundamental at 5.1kHz is 23dBmV
RMS
or 14mV
RMS
FREQUENCY (kHz)
255
O
R
)
–20
–25
–30
–35
–40
–45
–50
–55
–60
–65
–70
455
1307 F07
655
RBW = 100Hz
Figure 7. Span Centered at 455kHz Shows –55dBmV
RMS
(1.8
μ
V
RMS
) at 455kHz. Burst Mode Creates Sidebands 5.1kHz
Apart Around the Switching Frequency Fundamental of 575kHz
相關PDF資料 |
PDF描述 |
|---|---|
| LT1307BCS8 | Single Cell Micropower 600kHz PWM DC/DC Converters |
| LT1307CMS8 | Single Cell Micropower 600kHz PWM DC/DC Converters |
| LT1307CN8 | 8-Bit Identity Comparators (P=Q) with Enable and 20K Ohm Q-Input Pullup Resistors 20-SOIC 0 to 70 |
| LT1307CS8 | 8-Bit Identity Comparators (P=Q) with Enable and 20K Ohm Q-Input Pullup Resistors 20-SOIC 0 to 70 |
| LT1307BIS8 | Single Cell Micropower 600kHz PWM DC/DC Converters |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LT1307IS8#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 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:升壓（升壓） 輸出類型:可調式 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: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) 供應商設備封裝:8-SOIC |
| LT1308 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Single Cell High Current Micropower 600kHz Boost DC/DC Converter |
| LT1308A | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| LT1308A_1 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:High Current, Micropower Single Cell, 600kHz DC/DC Converters |
| LT1308ACF | 功能描述:IC REG BOOST 5V 1A 14TSSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:20 系列:SIMPLE SWITCHER® 類型:降壓（降壓） 輸出類型:固定 輸出數(shù):1 輸出電壓:12V 輸入電壓:4 V ~ 60 V PWM 型:電壓模式 頻率 - 開關:52kHz 電流 - 輸出:1A 同步整流器:無 工作溫度:-40°C ~ 125°C 安裝類型:通孔 封裝/外殼:16-DIP（0.300"，7.62mm） 包裝:管件 供應商設備封裝:16-DIP 其它名稱:*LM2575HVN-12LM2575HVN-12 |
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