參數(shù)資料
型號(hào)： PM6670S
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： 3 A SWITCHING CONTROLLER, QCC24
封裝： 4 X 4 MM, LEAD FREE, VFQFPN-24
文件頁(yè)數(shù)： 33/54頁(yè)
文件大?。?/td> 742K
代理商： PM6670S
PM6670S
Application information
Doc ID 14432 Rev 4
39/54
8
Application information
The purpose of this chapter is to show the design procedure of the switching section.
The design starts from three main specifications:
●
The input voltage range, provided by the battery or the AC adapter. The two extreme
values (VINMAX and VINmin) are important for the design.
●
The maximum load current, indicated by 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.
8.1
External components selection
The PM6670S 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 0.8 V and lower
than 2 V 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 24
where KOSC is a constant value (130 ns typ.) and τ is the internal propagation delay
(40 ns typ.).
The duty cycle of the buck converter is, under steady state conditions, given by
Equation 25
The switching frequency is thus calculated as
Equation 26
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
=
=
相關(guān)PDF資料
PDF描述
PM6670TR 1.4 A SWITCHING CONTROLLER, QCC24
PM6670ATR 1.4 A SWITCHING CONTROLLER, QCC24
PM6670 1.4 A SWITCHING CONTROLLER, QCC24
PM6675ASTR 3 A SWITCHING CONTROLLER, QCC24
PM6675AS 3 A SWITCHING CONTROLLER, QCC24
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PM6670STR 功能描述:DC/DC 開關(guān)控制器 Complete DDR2/3 Mem Pwr supply controllr 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
PM6670TR 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Complete DDR2/3 Mem Pwr supply controllr RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
PM6675 制造商:STMicroelectronics 功能描述: 制造商:STMicroelectronics 功能描述:LDO CNTRLR STDN 0.6V TO 3.3V/1.5V 24PIN VFQFPN - Rail/Tube
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
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