參數(shù)資料
型號(hào)： PM6670STR
廠商： STMICROELECTRONICS
元件分類(lèi)： 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)： 14/54頁(yè)
文件大小： 742K
代理商： PM6670STR
PM6670S
Device description
Doc ID 14432 Rev 4
21/54
7.1
VDDQ section - constant on-time PWM controller
The PM6670S uses a pseudo-fixed frequency, constant on-time (COT) controller as the core
of the switching section. It is well known that the COT controller uses a relatively simple
algorithm and uses the ripple voltage derived across the output capacitor’s ESR to trigger
the on-time one-shot generator. In this way, the output capacitor’s ESR acts as a current
sense resistor providing the appropriate ramp signal to the PWM comparator. 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 1
where KOSC is a constant value (130 ns typ.) and τ is the internal propagation delay (40ns
typ.). The one-shot generator directly drives the high-side MOSFET at the beginning of each
switching cycle allowing the inductor current to increase; after the on-time has expired, an
Off-Time phase, in which the low-side MOSFET is turned on, follows. The off-time duration
is solely determined by the output voltage: when lower than the set value (i.e. the voltage at
VSNS pin is lower than the internal reference VR = 0.9 V), the synchronous rectifier is turned
off and a new cycle begins (Figure 28).
Figure 28.
Inductor current and output voltage in steady state conditions
τ
+
=
OSC
SNS
OSC
ON
V
K
T
Ton
Toff
Inductor
current
t
Output
voltage
Vreg
Ton
Toff
Inductor
current
t
Output
voltage
Vreg
相關(guān)PDF資料
PDF描述
PM6670S 3 A SWITCHING CONTROLLER, QCC24
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PM6670ATR 1.4 A SWITCHING CONTROLLER, QCC24
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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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(kāi)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(kāi)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
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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(lèi)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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