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參數(shù)資料
| 型號： | LTC3618EFE#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 8 A DUAL SWITCHING CONTROLLER, 2700 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封裝： | 4.40 MM, LEAD FREE, PLASTIC, TSSOP-24 |
| 文件頁數(shù)： | 6/24頁 |
| 文件大?。?/td> | 603K |
| 代理商： | LTC3618EFE#TRPBF |
LTC3618
14
3618f
Phase Selection
VTT will operate in-phase, 180° out-of-phase (anti-phase)
or shifted by 90° from VDDQ depending on the state of the
PHASE pin—low, midrail or high, respectively. Antiphase
generally reduces input voltage and current ripple. Cross-
talk between switch nodes SW1, SW2 and components
or sensitive lines connected to FBx, ITHx, RT can cause
unstable switching waveforms and unexpectedly large
input and output voltage ripple.
The situation improves if rising and falling edges of the
switch nodes are timed carefully not to coincide. Depending
on the duty cycle of the two channels, choose the phase
difference between the channels to keep edges as far away
from each other as possible.
For a duty cycle of less than 40% for one channel and more
than 60% for the other channel, choose a phase shift of 0
or 180° (PHASE = SGND or SVIN). If both channels have
a duty cycle of around 50%, select a phase difference of
90° (PHASE = one-half SVIN).
Inductor Selection
For a given input and output voltage, the inductor value
and operating frequency determine the inductor ripple
current. The ripple current ΔIL increases with higher VIN
and decreases with higher inductance.
IL =
VOUT
fSW L
1–
VOUT
VIN(MAX)
Having a lower ripple current reduces the core losses
in the inductor, the ESR losses in the output capacitors
and the output voltage ripple. A reasonable starting point
for selecting the ripple current is ΔIL = 0.3(IOUT(MAX)).
Figure 4. Setting the Switching Frequency
APPLICATIONS INFORMATION
Frequency Synchronization
The LTC3618’s internal oscillator can be synchronized to
an external frequency by applying a square wave clock
signal to the MODE/SYNC pin. During synchronization,
the top MOSFET turn-on of VDDQ is locked to the rising
edge of the external frequency source. The synchronization
frequency range is 400kHz to 4MHz. The internal slope
compensation is automatically adapted to the external
clock frequency.
In the signal path from the MODE/SYNC clock input to the
SW output, the LTC3618 is processing the external clock
frequency through an internal PLL.
After detecting an external clock on the rst rising edge of
MODE/SYNC the PLL starts up with the internal default of
2.25MHz. The internal PLL then requires a certain number
of periods to settle until the frequency at SW matches the
frequency and phase of MODE/SYNC.
When the external clock signal is removed, the LTC3618
needs approximately 5μs to detect the absence of the
external clock. During this time, the PLL will continue to
provide clock cycles before it is switched back to the de-
fault frequency or selected frequency (set via the external
RT resistor).
In general, any abrupt clock frequency change of the
regulator will have an effect on the SW pin timing and
may cause equally sudden output voltage changes. This
must be taken into account in particular if the external
clock frequency is signicantly different from the internal
default of 2.25MHz.
LTC3618
SVIN
VIN
RT
LTC3618
SVIN
VIN
0.4V
RT
RT
SGND
fSW
2.25MHz
fSW ∝1/ROSC
3618 F04
LTC3618
SVIN
VIN
MODE/SYNC
SGND
fSW
1/TP
TP
1.2V
0.3V
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| LTC3618EUF#PBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
| LTC3618EUF#TRPBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
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| LTC3618IFE#TRPBF | 功能描述:IC REG DUAL SYNC 3A BUCK 24TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 標(biāo)準(zhǔn)包裝:43 系列:- 應(yīng)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(yīng)商設(shè)備封裝:48-QFN（7x7） 包裝:管件 |
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