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參數(shù)資料
| 型號(hào)： | PM6675 |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, QCC24 |
| 封裝： | 4 X 4 MM, VFQFPN-24 |
| 文件頁數(shù)： | 26/47頁 |
| 文件大?。?/td> | 650K |
| 代理商： | PM6675 |
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Application information
PM6675
32/47
7
Application information
The purpose of this chapter is showing the design procedure of the switching section.
The design starts from three main specifications:
●
The input voltage range, provided by the battery or the external supply. The two
extreme values (VINMAX and VINmin ) are important for the design.
●
The maximum load current, indicated with ILOAD,MAX.
●
The maximum allowed output voltage ripple VRIPPLE,MAX.
It's also possible that specific designs should involve other specifications.
The following paragraphs will guide the user into a step-by-step design.
7.1
External components selection
The PM6675 uses a pseudo-fixed frequency, Constant On-Time (COT) controller as the
core of the switching section. The switching frequency can be set by connecting an external
divider to the VOSC pin. The voltage seen at this pin must be greater than 0.8V and lower
than 2V in order to ensure system's linearity.
Nearly constant switching frequency is achieved by the system's loop in steady-state
operating conditions by varying the On-Time duration, avoiding thus the need for a clock
generator. The On-Time one shot duration is directly proportional to the output voltage,
sensed at VSNS pin, and inversely proportional to the input voltage, sensed at the VOSC
pin, as follows:
Equation 25
where KOSC is a constant value (130ns typ.) and τ is the internal propagation delay
(40ns typ.).
The duty cycle of the buck converter is, in under steady state conditions, given by
Equation 26
The switching frequency is thus calculated as
Equation 27
τ
+
=
OSC
SNS
OSC
ON
V
K
T
IN
OUT
V
D
=
OSC
OUT
OSC
SNS
OSC
IN
OUT
ON
SW
K
1
V
K
V
T
D
f
α
=
=
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PM6675AS | 功能描述:DC/DC 開關(guān)控制器 DDR 2/3 Memory Pwr Cntrl RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| PM6675ASTR | 功能描述:低壓差控制器 - LDO Complete DDR2/3 Mem Pwr supply controllr RoHS:否 制造商:Micrel 最大輸入電壓:5.5 V 輸出電壓:Adjustable 輸出電流:10 mA 負(fù)載調(diào)節(jié): 輸出類型:Adjustable, Fixed 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-6 |
| PM6675ATR | 功能描述:低壓差控制器 - LDO High eff SD CNRL RoHS:否 制造商:Micrel 最大輸入電壓:5.5 V 輸出電壓:Adjustable 輸出電流:10 mA 負(fù)載調(diào)節(jié): 輸出類型:Adjustable, Fixed 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-6 |
| PM6675S | 功能描述:DC/DC 開關(guān)控制器 DDR 2/3 Memory Pwr Cntrl RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| PM6675STR | 功能描述:低壓差控制器 - LDO Complete DDR2/3 Mem Pwr supply controllr RoHS:否 制造商:Micrel 最大輸入電壓:5.5 V 輸出電壓:Adjustable 輸出電流:10 mA 負(fù)載調(diào)節(jié): 輸出類型:Adjustable, Fixed 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-6 |
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