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參數(shù)資料
| 型號(hào)： | PTN78000AAST |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 電源模塊 |
| 英文描述： | 1-OUTPUT 9 W DC-DC REG PWR SUPPLY MODULE |
| 封裝： | DIP-5 |
| 文件頁(yè)數(shù)： | 5/19頁(yè) |
| 文件大?。?/td> | 492K |
| 代理商： | PTN78000AAST |
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Optional Input/Output Filters
Input/Output Capacitors
C4
100 F
(Required)
m
(See Note B)
C3
2 x 4.7 F
Ceramic
(Required)
m
(See Note A)
C2
100 F
Electrolytic
(Required)
m
C1
4.7 F
Ceramic
m
RSET
C5
4.7 F
Ceramic
m
GND
PTN78000A
4
1
2
VI
VO
GND
5
Adj
π Filters
PTN78000A
SLTS246B–APRIL 2005–REVISED JANUARY 2006
Power modules include internal input and output ceramic capacitors in all their designs. However, some
applications require much lower levels of either input reflected or output ripple/noise. This application describes
various filters and design techniques found to be successful in reducing both input and output ripple/noise.
The easiest way to reduce output ripple and noise is to add one or more 1-μF ceramic capacitors, such as C5
shown in Figure 19. Ceramic capacitors should be placed close to the output power terminals. A single 4.7-μF
capacitor reduces the output ripple/noise by 10% to 30% for modules with a rated output current of less than 3 A.
(Note: C4 is recommended to improve the regulators transient response and does not reduce output ripple and
noise.)
Switching regulators draw current from the input line in pulses at their operating frequency. The amount of
reflected (input) ripple/noise generated is directly proportional to the equivalent source impedance of the power
source including the impedance of any input lines. The addition of C1, minimum 4.7-μF ceramic capacitor, near
the input power pins, reduces reflected conducted ripple/noise by 20% to 30%.
A.
See specifications for required value and type.
B.
See Application Information for suggested value and type.
Figure 19. Adding High-Frequency Bypass Capacitors to the Input and Output
If a further reduction in ripple/noise level is required for an application, higher order filters must be used. A π (pi)
filter, employing a ferrite bead (Fair-Rite Pt. No. 2673000701 or equivalent) in series with the input or output
terminals of the regulator reduces the ripple/noise by at least 20 db (see Figure 20 and Figure 21). In order for
the inductor to be effective in reduction of ripple and noise ceramic capacitors are required. (See the Capacitor
Recommendations for the PTN78000A for additional information on vendors and component suggestions.)
These inductors plus ceramic capacitors form an excellent filter because of the rejection at the switching
frequency (650 kHz - 1 MHz). The placement of this filter is critical. It must be located as close as possible to the
input or output pins to be effective. The ferrite bead is small (12,5 mm × 3 mm), easy to use, low cost, and has
low dc resistance. Fair-Rite also manufactures a surface-mount bead (part number 2773021447), through hole
(part number 2673000701) rated to 5 A. Alternatively, 1-μHto 5-μH inductors can be used in place of the ferrite
inductor bead.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PTN78000AAZ | 功能描述:DC/DC轉(zhuǎn)換器 1.5A Wide Inp/ Neg Out Adj Module RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓（標(biāo)稱）: 輸出端數(shù)量:1 輸出電壓（通道 1）:3.3 V 輸出電流（通道 1）:600 mA 輸出電壓（通道 2）: 輸出電流（通道 2）: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸: |
| PTN78000AAZT | 功能描述:DC/DC轉(zhuǎn)換器 1.5A Wide Inp/ Neg Out Adj Module RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓（標(biāo)稱）: 輸出端數(shù)量:1 輸出電壓（通道 1）:3.3 V 輸出電流（通道 1）:600 mA 輸出電壓（通道 2）: 輸出電流（通道 2）: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸: |
| PTN78000H | 制造商:TI 制造商全稱:Texas Instruments 功能描述:1.5-A, WIDE-INPUT ADJUSTABLE SWITCHING REGULATOR |
| PTN78000HAH | 功能描述:DC/DC轉(zhuǎn)換器 1.5 A Wide I/O Adj Module RoHS:否 制造商:Murata 產(chǎn)品: 輸出功率: 輸入電壓范圍:3.6 V to 5.5 V 輸入電壓（標(biāo)稱）: 輸出端數(shù)量:1 輸出電壓（通道 1）:3.3 V 輸出電流（通道 1）:600 mA 輸出電壓（通道 2）: 輸出電流（通道 2）: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體尺寸: |
| PTN78000HAH | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
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