- 您現(xiàn)在的位置：買(mǎi)賣(mài)IC網(wǎng) > PDF目錄377761 > LTC1700 (Linear Technology Corporation) Quadruple 2-Input Exclusive-OR Gates 14-SO 0 to 70 PDF資料下載
參數(shù)資料
| 型號(hào)： | LTC1700 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | Quadruple 2-Input Exclusive-OR Gates 14-SO 0 to 70 |
| 中文描述： | 無(wú)檢測(cè)電阻同步升壓型DC / DC控制器 |
| 文件頁(yè)數(shù)： | 7/16頁(yè) |
| 文件大?。?/td> | 194K |
| 代理商： | LTC1700 |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)當(dāng)前第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)
LTC1700
7
Frequency Synchronization
The LTC1700 can be externally driven by a CMOS
(0V to 1.2V) compatible clock signal between 400kHz and
750kHz. Do notsynchronize the LTC1700 below 400kHz
or above 750kHz as this may cause abnormal operation.
During synchronization, Burst Mode operation is
inhibited.
Low Input Operation
When the voltage at V
OUT
is less than 2.3V, the LTC1700
operates in the “start-up” mode. In this mode, most
internal circuitry is turned off except the start-up oscilla-
tor, current comparator (I
CMP
) and the start-up compara-
tor (SC). The voltage at pins TG and BG are forced to
ensure both the external MOSFETs are off. The start-up
oscillator runs at about 210kHz at 50% duty cycle and is
used to set the latch (L1) which turns on the internal
MOSFET M1 (see Functional Diagram). When the inductor’s
current reaches 60mA, the current comparator (I
CMP
) is
tripped and resets the latch. This turns M1 off and the
parasitic diode of the external P-channel MOSFET is used
to transfer the energy from the inductor to the output
capacitor. The above cycle repeats again on the next
oscillator pulse.
When the output voltage rises above 2.3V, the start-up
comparator will trip, powering up the rest of the LTC1700.
All start-up circuitry will then be turned off. Now the
LTC1700 has successfully transitioned out of its start-up
mode and commences normal operation as described
under the section “Main Control Loop.”
Protection Circuitry
Two protection circuits are incorporated into the LTC1700.
To prevent the inductor from saturating the maximum
duty cycle of the regulator is limited to 90%. This is done
to ensure that at least 10% of the time energy is being
transferred from the inductor to the output capacitor.
Output overvoltage protection is also provided. Should the
output rises about 5% above the regulated value, both the
external MOSFETs will be forced off.
OPERATIOU
output feedback voltage V
FB
. When the load current in-
creases, it causes a slight decreases in V
FB
relative to the
1.205V reference, which in turn causes the I
TH
voltage to
increase until the average inductor current matches the
new load current.
The internal oscillator can be synchronized to an external
clock applied to the SYNC/MODE pin and can lock to a
frequency between 400kHz to 750kHz. When not synchro-
nized, the oscillator runs at 530kHz.
The main control loop is shut down by pulling the RUN/SS
pin low. Releasing the RUN/SS pin allows an internal
3.8
μ
A current source to charge up an external soft-start
capacitor (C
SS)
. When this voltage reaches 0.8V, the main
control loop is enabled with the I
TH
voltage clamped at
approximately 5% of its maximum value. As C
SS
contin-
ues to charge, I
TH
is gradually released allowing normal
operation to resume.
An overvoltage comparator 0V guards against transient
overshoots greater than 5% above regulated voltage by
turning off both the external MOSFETs and keeping them
off until the fault is removed.
To prevent excessive inductor current buildup, the main
N-channel MOSFET is only allowed to turn on for a
maximum duty cycle of 90%.
Burst Mode Operation
The LTC1700 can be enabled to go into Burst Mode
operation at low load currents simply by connecting the
SYNC/MODE pin to a voltage of at least 1.2V. In this mode,
the peak current of the inductor is set as if V
ITH
= 0.36V (at
low duty cycles) even though the voltage at the I
TH
pin is
actually at a lower value. If the inductor’s average current
is greater than the load requirement, the voltage at the I
TH
pin will drop. When the I
TH
voltage goes below 0.12V, the
internal sleep signal goes low, turning off both external
MOSFETs. Now the load current will solely be supplied by
the output capacitor and the output voltage begins to
droop. This drooping of the output voltage results in the
rise of I
TH
voltage and once it has risen above 0.22V,
switching will then be resumed on the next oscillator cycle.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1700EMS | Synchronous 8-Bit Up/Down Binary Counters 24-SOIC 0 to 70 |
| LTC1702CGN | Dual 550kHz Synchronous 2-Phase Switching Regulator Controller |
| LTC1702 | Synchronous 8-Bit Up/Down Binary Counters 24-SOIC 0 to 70 |
| LTC1702C | Synchronous 8-Bit Up/Down Binary Counters 24-SOIC 0 to 70 |
| LTC1702I | Synchronous 8-Bit Up/Down Binary Counters 24-SOIC 0 to 70 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1700EMS | 功能描述:IC REG CTRLR BST PWM CM 10-MSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR) |
| LTC1700EMS#PBF | 功能描述:IC REG CTRLR BST PWM CM 10-MSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤(pán) 包裝:Digi-Reel® 產(chǎn)品目錄頁(yè)面:1303 (CN2011-ZH PDF) 其它名稱(chēng):LM3754SQDKR |
| LTC1700EMS#TR | 功能描述:IC REG CTRLR BST PWM CM 10-MSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR) |
| LTC1700EMS#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 10-MSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無(wú) 升壓:是 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤(pán) 包裝:帶卷 (TR) |
| LTC1701BES5 | 制造商:Linear Technology 功能描述:1.1 A SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PDSO5 |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。