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參數資料
| 型號： | LTC3835IGN-1 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 3 A SWITCHING CONTROLLER, 580 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | 0.150 INCH, PLASTIC, SSOP-16 |
| 文件頁數： | 28/28頁 |
| 文件大?。?/td> | 303K |
| 代理商： | LTC3835IGN-1 |
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LTC3835-1
9
38351fc
OPERATION (Refer to Functional Diagram)
Main Control Loop
The LTC3835-1 uses a constant-frequency, current mode
step-down architecture. During normal operation, each
external top MOSFET is turned on when the clock sets the
RS latch, and is turned off when the main current compara-
tor, ICMP, resets the RS latch. The peak inductor current
at which ICMP trips and resets the latch is controlled by
the voltage on the ITH pin, which is the output of the error
amplier EA. The error amplier compares the output volt-
age feedback signal at the VFB pin, (which is generated with
an external resistor divider connected across the output
voltage, VOUT, to ground) to the internal 0.800V reference
voltage. When the load current increases, it causes a slight
decrease in VFB relative to the reference, which cause the
EA to increase the ITH voltage until the average inductor
current matches the new load current.
After the top MOSFET is turned off each cycle, the bottom
MOSFET is turned on until either the inductor current starts
to reverse, as indicated by the current comparator IR, or
the beginning of the next clock cycle.
INTVCC Power
Power for the top and bottom MOSFET drivers and most
other internal circuitry is derived from the INTVCC pin.
An internal 5.25V low dropout linear regulator supplies
INTVCC power from VIN.
The top MOSFET driver is biased from the oating bootstrap
capacitor CB, which normally recharges during each off
cycle through an external diode when the top MOSFET
turns off. If the input voltage VIN decreases to a voltage
close to VOUT, the loop may enter dropout and attempt
to turn on the top MOSFET continuously. The dropout
detector detects this and forces the top MOSFET off for
about one twelfth of the clock period every tenth cycle to
allow CB to recharge.
Shutdown and Start-Up (RUN and TRACK/SS Pins)
The LTC3835-1 can be shut down using the RUN pin. Pulling
this pin below 0.7V shuts down the main control loop for the
controller. A low disables the controller and most internal
circuits, including the INTVCC regulator, at which time the
LTC3835-1 draws only 10μA of quiescent current.
Releasing the RUN pin allows an internal 0.5μA current
to pull up the pin and enable that controller. Alternatively,
the RUN pin may be externally pulled up or driven directly
by logic. Be careful not to exceed the Absolute Maximum
rating of 7V on this pin.
The start-up of the output voltage VOUT is controlled by
the voltage on the TRACK/SS pin. When the voltage on
the TRACK/SS pin is less than the 0.8V internal reference,
the LTC3835-1 regulates the VFB voltage to the TRACK/SS
pin voltage instead of the 0.8V reference. This allows
the TRACK/SS pin to be used to program a soft-start by
connecting an external capacitor from the TRACK/SS pin
to SGND. An internal 1μA pull-up current charges this
capacitor creating a voltage ramp on the TRACK/SS pin.
As the TRACK/SS voltage rises linearly from 0V to 0.8V
(and beyond), the output voltage VOUT rises smoothly
from zero to its nal value.
Alternatively the TRACK/SS pin can be used to cause the
start-up of VOUT to “track” that of another supply. Typi-
cally, this requires connecting to the TRACK/SS pin an
external resistor divider from the other supply to ground
(see Applications Information section).
When the RUN pin is pulled low to disable the LTC3835-1,
or when VIN drops below its undervoltage lockout thresh-
old of 3.5V, the TRACK/SS pin is pulled low by an internal
MOSFET. When in undervoltage lockout, the controller is
disabled and the external MOSFETs are held off.
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相關代理商/技術參數 |
參數描述 |
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| LTC3835IGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數: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 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3835IGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3835IUFD#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 特色產品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標準包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數: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 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3835IUFD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 20-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數:1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3836EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
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