- 您现在的位置：买卖IC网 > PDF目录1833 > LTC3879EUD#PBF (Linear Technology)IC REG CTRLR BUCK PWM CM 16-QFN PDF资料下载
参数资料
| 型号： | LTC3879EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-QFN |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2MHz |
| 占空比： | 90% |
| 电源电压： | 4 V ~ 38 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： | -40°C ~ 85°C |
| 封装/外壳： | 16-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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页当前第10页第11页第12页第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
LTC3879
OPERATION
Main Control Loop
The LTC3879 is a valley current mode controller IC for
use in DC/DC step-down converters. In normal continu-
ous operation, the top MOSFET is turned on for a ?xed
interval determined 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
valley current is measured by sensing the voltage between
the PGND and SW pins using the bottom MOSFET on-
resistance. The voltage on the I TH pin sets the compara-
tor threshold corresponding to inductor valley current.
The error ampli?er EA adjusts this voltage by comparing
the feedback signal V FB from the output voltage to the
feedback reference voltage V FBREF . Increasing the load
current causes a drop in the feedback voltage relative
to the reference. The EA senses the feedback voltage
drop and adjusts the I TH voltage higher until the average
inductor current matches the load current.
With DC current loads less than 1/2 of the peak-to-peak
ripple the inductor current can drop to zero or become
negative. In discontinuous operation, negative inductor
current is detected and prevented by the current reversal
comparator I REV , which shuts off MB. Both switches remain
off with the output capacitor supplying the load current
until the EA moves the I TH voltage above the zero current
level (0.8V) to initiate another switching cycle. When the
the regulator is forced to operate in continuous mode by
disabling reversal comparator, I REV , thereby allowing the
inductor current to become negative.
The continuous mode operating frequency can be deter-
mined by dividing the calculated duty cycle, V OUT /V IN ,
by the ?xed on-time. The OST generates an on-time
proportional to the ideal duty cycle, thus holding the
frequency approximately constant with changes in V IN .
The nominal frequency can be adjusted with an external
resistor, R ON .
Foldback current limiting is provided to protect against
low impedance shorts. If the controller is in current limit
and V OUT drops to less 50% of regulation, the current limit
set-point “folds back” to progressively lower values. To
recover from foldback current limit, the excessive load or
low impedance short needs to be removed.
When RUN is less than 0.7V, the LTC3879 is in the low
power shutdown state with a nominal bias current of
18μA. When RUN is greater than 0.7V and less than 1.5V,
INTV CC and all internal circuitry are enabled while TG and
BG are forced low. When RUN is taken greater than 1.5V,
switching begins and the TRACK/SS pin is released from
ground. The output voltage follows the TRACK/SS input
multiplied by feedback factor when TRACK/SS is less than
0.6V. Soft-start is complete when TRACK/SS exceeds the
internal 0.6V reference voltage and regulates normally.
MODE pin is below the internal threshold reference, V MODE ,
3879f
10
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3880EUJ-1#PBF | IC REG CTRLR BUCK PWM CM 40-QFN |
| LTC3890EUH#PBF | IC REG CTRLR BUCK PWM CM 32-QFN |
| LTC3891EFE#PBF | IC REG CTRLR BUCK PWM CM 20TSSOP |
| LTC4000IGN#TRPBF | IC CHARGER BATTERY 28-SSOP |
| LTC4001EUF#TRPBF | IC CHARGER LI-ION BUCK 16-QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3879IMSE#PBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3879IMSE#TRPBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3879IUD#PBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3879IUD#TRPBF | 功能描述:IC REG CTRLR BUCK 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) |
| LTC3880EUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN 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。