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參數(shù)資料
| 型號(hào)： | PTH04040WAST |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 電源模塊 |
| 英文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 封裝： | ROHS COMPLIANT, DIP-20 |
| 文件頁數(shù)： | 18/22頁 |
| 文件大?。?/td> | 747K |
| 代理商： | PTH04040WAST |
Application Notes
For technical support and more information, see inside back cover or visit www.ti.com
PTH04040W
Capacitor Recommendations for
the
PTH04040 Power Modules
The PTH04040W uses state-of-the-art multi-phase
power converter topology that employs multiple parallel
switching and filter inductor paths between the input
and output capacitors. The PTH04040W uses three
switching paths. The three paths share the total load
current, operate at the same frequency, and are evenly
displaced in phase.
With multiple switching paths the transient output cur-
rent capability is significantly increased. This reduces
the amount of external output capacitance required to
support a load transient. As a further benefit, the ripple
current, as seen by the input and output capacitors, is
reduced in magnitude and effectively tripled in frequency.
Input Capacitor
The improved transient response of a multi-phase con-
verter places a bigger burden on the transient capability of
the input source. The size and value of the input capaci-
tor is therefore determined by this converter’s transient
performance capability. The minimum amount of input
capacitance required is 1,000 F (or 3
× 330 F), with an
RMS ripple current rating of 400 mA. This minimum
value assumes that the converter is supplied with a respon-
sive, low-inductance input source. This source should
have ample capacitive decoupling and be distributed to
the converter via PCB power and ground planes. For high-
performance applications, or wherever the transient
capability of the input source is limited, 2,200 F of
input capacitance is recommended.
Ripple current and less than 100 m
equivalent series
resistance (ESR) values are the major considerations,
along with temperature, when designing with different
types of capacitors. Unlike polymer tantalum, conven-
tional tantalum capacitors have a recommended minimum
voltage rating of 2
× (maximum DC voltage + AC ripple).
This is standard practice to ensure reliability.
For improved ripple reduction on the input bus, ceramic
capacitors may be used to complement electrolytic types
and achieve the minimum required capacitance.
Output Capacitors (Recommended)
In order to respond with load transients (sudden changes
in load current) the regulator requires external output
capacitance. The minimum output capacitance is 660 F
(2
× 330 F or 1 × 680 F) with an ESR of at least 2 m.
This output capacitance is required for the module to
meet its transient response specification (see product data
sheet). For most applications a high quality computer-
grade aluminum electrolytic capacitor is suitable. These
capacitors provide adequate decoupling over the frequency
range, 2 kHz to 150 kHz, and when ambient temperatures
are above 0 °C. For operation below 0 °C, tantalum,
ceramic or Os-Con type capacitors are recommended.
When using one or more non-ceramic capacitors, the
calculated equivalent ESR should be no lower than 4 m
(7 m
using the manufacturer’s maximum ESR for a single
capacitor). A list of preferred low-ESR type capacitors
are identified in Table 1-1.
Ceramic Capacitors
Above 150 kHz the performance of aluminum electrolytic
capacitors becomes less effective. To further improve the
reflected input ripple current or the output transient
response, multilayer ceramic capacitors can also be added.
Ceramic capacitors have very low ESR and their resonant
frequency is higher than the bandwidth of the regulator.
When used on the output their combined ESR is not
critical as long as the total value of ceramic capacitance
does not exceed 300 F. Also, to prevent the formation of
local resonances, do not place more than five identical ce-
ramic capacitors in parallel with values of 10 F or greater.
Tantalum Capacitors
Tantalum type capacitors can be used at both the input
and output, and are recommended for applications where
the ambient operating temperature can be less than 0 °C.
The AVX TPS, Sprague 593D/594/595 and Kemet T495/
T510 capacitor series are suggested over many other
tantalum types due to their higher rated surge, power
dissipation, and ripple current capability. As a caution
many general purpose tantalum capacitors have consider-
ably higher ESR, reduced power dissipation and lower
ripple current capability. These capacitors are also less
reliable when determining their power dissipation and
surge current capability. Tantalum capacitors that do
not have a stated ESR or surge current rating are not
recommended for power applications.
When specifying Os-Con and polymer tantalum capacitors
for the output, the minimum ESR limit will be encoun-
tered well before the maximum capacitance value is
reached.
Capacitor Table
Table 1-1 identifies the characteristics of capacitors from a
number of vendors with acceptable ESR and ripple current
(rms) ratings. The recommended number of capacitors
required at both the input and output buses is identified
for each capacitor type.
This is not an extensive capacitor list. Capacitors from other
vendors are available with comparable specifications. Those
listed are for guidance. The RMS ripple current rating and
ESR (at 100kHz) are critical parameters necessary to insure
both optimum regulator performance and long capacitor life.
Designing for Very Fast Load Transients
The transient response of the DC/DC converter has been
characterized using a load transient with a di/dt of 1 A/s.
The typical voltage deviation for this load transient is
given in the data sheet specification table using the
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| PTH04040WAZ | 功能描述:DC/DC轉(zhuǎn)換器 60A 3.3/5V-In Wide Output Adj Pwr Mdl 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: |
| PTH04040WAZT | 功能描述:DC/DC轉(zhuǎn)換器 2.95-5.5Vin 0.8-3.6V 2.045" x1.045"x0.357 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: |
| PTH04070W | 制造商:TI 制造商全稱:Texas Instruments 功能描述:3-A, 3.3/5-V INPUT ADJUSTABLE SWITCHING REGULATOR |
| PTH04070W_07 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:3-A, 3.3/5-V INPUT ADJUSTABLE SWITCHING REGULATOR |
| PTH04070WAD | 功能描述:DC/DC轉(zhuǎn)換器 3-A 3.3/5-V Input Adj Swtch Regulator 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: |
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