参数资料
| 型号： | LTC3786EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/34页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 16-QFN |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 850kHz |
| 占空比： | 100% |
| 电源电压： | 4.5 V ~ 38 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 包装： | 管件 |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页当前第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页
LTC3786
OPERATION
(Refer to the Block Diagram)
The typical capture range of the LTC3786’s PLL is from
approximately 55kHz to 1MHz, and is guaranteed to lock
to an external clock source whose frequency is between
75kHz and 850kHz.
The typical input clock thresholds on the PLLIN/MODE
pin are 1.6V (rising) and 1.2V (falling).
Operation When V IN > Regulated V OUT
When V IN rises above the regulated V OUT voltage, the boost
controller can behave differently depending on the mode,
inductor current and V IN voltage. In forced continuous
mode, the loop keeps the top MOSFET on continuously once
V IN rises above V OUT . The internal charge pump delivers
current to the boost capacitor to maintain a sufficiently
high TG voltage. (The amount of current the charge pump
can deliver is characterized by two curves in the Typical
Performance Characteristics section.)
In pulse-skipping mode, if V IN is between 100% and 110%
of the regulated V OUT voltage, TG turns on if the inductor
current rises above a certain threshold and turns off if the
inductor current falls below this threshold. This threshold
current is set to approximately 4% of the maximum ILIM
current. If the controller is programmed to Burst Mode
operation under this same V IN window, then TG remains
off regardless of the inductor current.
If V IN rises above 110% of the regulated V OUT voltage in
any mode, the controller turns on TG regardless of the
inductor current. In Burst Mode operation, however, the
internal charge pump turns off if the chip is asleep. With
the charge pump off, there would be nothing to prevent
the boost capacitor from discharging, resulting in an
insufficient TG voltage needed to keep the top MOSFET
completely on. To prevent excessive power dissipation
across the body diode of the top MOSFET in this situa-
tion, the chip can be switched over to forced continuous
or pulse-skipping mode to enable the charge pump, or a
Schottky diode can also be placed in parallel to the top
MOSFET.
Power Good
The PGOOD pin is connected to an open-drain of an
internal N-channel MOSFET. The MOSFET turns on and
pulls the PGOOD pin low when the VFB pin voltage is not
within ±10% of the 1.2V reference voltage. The PGOOD
pin is also pulled low when the corresponding RUN pin
is low (shut down). When the VFB pin voltage is within
the ±10% requirement, the MOSFET is turned off and the
pin is allowed to be pulled up by an external resistor to a
source of up to 6V (abs max).
Operation at Low SENSE Pin Common Mode Voltage
The current comparator in the LTC3786 is powered directly
from the SENSE + pin. This enables the common mode
voltage of SENSE + and SENSE – pins to operate as low
as 2.5V, which is below the INTV CC UVLO threshold. The
figure on the first page shows a typical application when
the controller’s VBIAS is powered from V OUT while V IN
supply can go as low as 2.5V. If the voltage on SENSE +
drops below 2.5V, the SS pin will be held low. When the
SENSE + voltage returns to the normal operating range, the
SS pin will be released, initiating a new soft-start cycle.
BOOST Supply Refresh and Internal Charge Pump
The top MOSFET driver is biased from the floating boot-
strap capacitor, C B , which normally recharges during each
cycle through an external diode when the bottom MOSFET
turns on. There are two considerations to keep the BOOST
supply at the required bias level. During start-up, if the
bottom MOSFET is not turned on within 100μs after UVLO
goes low, the bottom MOSFET will be forced to turn on
for ~400ns. This forced refresh generates enough BOOST-
SW voltage to allow the top MOSFET to be fully enhanced
instead of waiting for the initial few cycles to charge the
bootstrap capacitor, C B . There is also an internal charge
pump that keeps the required bias on BOOST. The charge
pump always operates in both forced continuous mode
and pulse-skipping mode. In Burst Mode operation, the
charge pump is turned off during sleep and enabled when
the chip wakes up. The internal charge pump can normally
supply a charging current of 85μA.
3786fa
13
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3787EUFD#PBF | IC REG CTRLR BST PWM CM 28-QFN |
| LTC3788IUH#TRPBF | IC REG CTRLR BST PWM CM 32-QFN |
| LTC3789EGN#PBF | IC REG CTRLR BST PWM CM 28-SSOP |
| LTC3801BES6#TRM | IC REG CTRLR BUCK PWM TSOT23-6 |
| LTC3802EGN | IC REG CTRLR BUCK PWM VM 28-SSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3786IMSE#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3786IMSE#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3786IUD#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3786IUD#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3787EGN#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
发布紧急采购，3分钟左右您将得到回复。