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參數(shù)資料
| 型號： | LTC3714 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Intel Compatible, Wide Operating Range, Step-Down Controller with Internal Op Amp |
| 中文描述： | 英特爾兼容，寬工作電壓范圍，降壓型控制器內部運算放大器 |
| 文件頁數(shù)： | 10/28頁 |
| 文件大?。?/td> | 345K |
| 代理商： | LTC3714 |
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LTC3714
10
3714f
Main Control Loop
The LTC3714 is a constant on-time, current mode control-
ler for DC/DC step-down converters. In normal operation,
the top MOSFET is turned on for a fixed interval deter-
mined by a one-shot timer OST. When the top MOSFET is
turned off, the bottom MOSFET is turned on until the
current comparator I
CMP
trips, restarting the one-shot
timer and initiating the next cycle. Inductor current is
determined by sensing the voltage between the PGND and
SENSE pins using either the bottom MOSFET on-resis-
tance or a separate sense resistor. The voltage on the I
TH
pin sets the comparator threshold corresponding to in-
ductor valley current. The error amplifier EA adjusts this
voltage by comparing the feedback signal V
FB
from the
output voltage with an internal 0.6V reference. The feed-
back voltage is derived from the output voltage by a
resistive divider DAC that is set by the VID code pins VID0-
VID4. If the load current increases, it causes a drop in the
feedback voltage relative to the reference. The I
TH
voltage
then rises until the average inductor current again matches
the load current.
At low load currents, the inductor current can drop to zero
and become negative. This is detected by current reversal
comparator I
REV
which then shuts off M2, resulting in
discontinuous operation. Both switches will remain off
with the output capacitor supplying the load current until
the I
TH
voltage rises above the zero current level (0.8V) to
initiate another cycle. Continuous synchronous operation
can be forced in the LTC3714 by bringing the FCB pin
below 0.6V. The benefit of forced continuous operation is
lower output voltage ripple, faster transient response to
current load steps and a much quieter frequency spectrum
so that it won’t interfere with any neighboring noise
sensitive components.
OPERATIOU
The operating frequency is determined implicitly by the
top MOSFET on-time and the duty cycle required to
maintain regulation. The one-shot timer generates an on-
time that is proportional to the ideal duty cycle, thus
holding frequency approximately constant with changes
in V
IN
and V
OUT
. The nominal frequency can be adjusted
with an external resistor R
ON
.
Overvoltage and undervoltage comparators OV and UV
pull the PGOOD output low if the output feedback voltage
exits a
±
10% window around the regulation point. Further-
more, in an overvoltage condition, M1 is turned off and M2
is turned on and held on until the overvoltage condition
clears.
Foldback current limiting is provided if the output is
shorted to ground. As V
FB
drops, the buffered current
threshold voltage I
THB
is pulled down by clamp Q3 to a 1V
level set by Q2 and Q6. This reduces the inductor valley
current level to one sixth of its maximum value as V
FB
approaches ground.
Pulling the RUN/SS pin low forces the controller into its
shutdown state, turning off both M1 and M2. Releasing
the pin allows an internal 1.2
μ
A current source to charge
up an external soft-start capacitor C
SS
. When this voltage
reaches 1.5V, the controller turns on and begins switch-
ing, but with the I
TH
voltage clamped at approximately
0.6V below the RUN/SS voltage. As C
SS
continues to
charge, the soft-start current limit is removed.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3714EG | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3714EG#PBF | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:2,000 系列:- 應用:控制器，DSP 輸入電壓:4.5 V ~ 25 V 輸出數(shù):2 輸出電壓:最低可調至 1.2V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:30-TFSOP（0.173"，4.40mm 寬） 供應商設備封裝:30-TSSOP 包裝:帶卷 (TR) |
| LTC3714EG#PBF | 制造商:Linear Technology 功能描述:DC/DC CONVERTER IC |
| LTC3714EG#TR | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3714EG#TRPBF | 功能描述:IC STP-DWN CNTRLR W/OPAMP 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標準包裝:43 系列:- 應用:控制器，Intel VR11 輸入電壓:5 V ~ 12 V 輸出數(shù):1 輸出電壓:0.5 V ~ 1.6 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:48-VFQFN 裸露焊盤 供應商設備封裝:48-QFN（7x7） 包裝:管件 |
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