- 您现在的位置：买卖IC网 > PDF目录15317 > LTC3850IUF#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 28-QFN PDF资料下载
参数资料
| 型号： | LTC3850IUF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/38页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-QFN |
| 产品培训模块： | LTC3850 Dual Output DC/DC Switching Regulator Controller |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 860kHz |
| 占空比： | 97.2% |
| 电源电压： | 4 V ~ 30 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： | 28-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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页当前第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页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页
LTC3850/LTC3850-1
OPERATION
Main Control Loop
The LTC3850 is a constant-frequency, current mode step-
down controller with two channels operating 180 degrees
out-of-phase. During normal operation, each top MOSFET
is turned on when the clock for that channel sets the RS
latch, and turned off when the main current comparator,
I CMP , resets the RS latch. The peak inductor current at
which I CMP resets the RS latch is controlled by the voltage
on the I TH pin, which is the output of each error ampli-
fier EA. The V FB pin receives the voltage feedback signal,
which is compared to the internal reference voltage by the
EA. When the load current increases, it causes a slight
decrease in V FB relative to the 0.8V reference, which in
turn causes the I TH voltage to increase until the average
inductor current matches the new load current. After the
top MOSFET has turned off, the bottom MOSFET is turned
on until either the inductor current starts to reverse, as
indicated by the reverse current comparator I REV , or the
beginning of the next cycle.
INTV CC /EXTV CC Power
Power for the top and bottom MOSFET drivers and most
other internal circuitry is derived from the INTV CC pin. When
the EXTV CC pin is left open or tied to a voltage less than
4.7V, an internal 5V linear regulator supplies INTV CC power
from V IN . If EXTV CC is taken above 4.7V, the 5V regulator is
turned off and an internal switch is turned on connecting
EXTV CC . Using the EXTV CC pin allows the INTV CC power
to be derived from a high efficiency external source such
as one of the LTC3850 switching regulator outputs.
Each top MOSFET driver is biased from the floating boot-
strap capacitor C B , which normally recharges during each
off cycle through an external diode when the top MOSFET
turns off. If the input voltage V IN decreases to a voltage
close to V OUT , 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 third cycle to
allow C B to recharge. However, it is recommended that a
load be present during the drop-out transition to ensure
C B is recharged.
Shutdown and Start-Up (RUN1, RUN2 and TK/SS1,
TK/SS2 Pins)
The two channels of the LTC3850 can be independently
shut down using the RUN1 and RUN2 pins. Pulling either
of these pins below 1.2V shuts down the main control
loop for that controller. Pulling both pins low disables both
controllers and most internal circuits, including the INTV CC
regulator. Releasing either RUN pin allows an internal
0.5μA current to pull up the pin and enable that control-
ler. Alternatively, the RUN pin may be externally pulled up
or driven directly by logic. Be careful not to exceed the
Absolute Maximum Rating of 6V on this pin.
The start-up of each controller’s output voltage V OUT is
controlled by the voltage on the TK/SS1 and TK/SS2 pins.
When the voltage on the TK/SS pin is less than the 0.8V
internal reference, the LTC3850 regulates the V FB voltage
to the TK/SS pin voltage instead of the 0.8V reference. This
allows the TK/SS pin to be used to program a soft-start
by connecting an external capacitor from the TK/SS pin
to SGND. An internal 1.3μA pull-up current charges this
capacitor, creating a voltage ramp on the TK/SS pin. As the
TK/SS voltage rises linearly from 0V to 0.8V (and beyond),
the output voltage V OUT rises smoothly from zero to its final
value. Alternatively the TK/SS pin can be used to cause the
start-up of V OUT to “track” that of another supply. Typically,
this requires connecting to the TK/SS pin an external resistor
divider from the other supply to ground (see the Applica-
tions Information section). When the corresponding RUN
pin is pulled low to disable a controller, or when INTV CC
drops below its undervoltage lockout threshold of 3V, the
TK/SS pin is pulled low by an internal MOSFET. When in
undervoltage lockout, both controllers are disabled and
the external MOSFETs are held off.
Light Load Current Operation (Burst Mode Operation,
Pulse-Skipping, or Continuous Conduction)
The LTC3850 can be enabled to enter high efficiency Burst
Mode operation, constant-frequency pulse-skipping mode,
or forced continuous conduction mode. To select forced
continuous operation, tie the MODE/PLLIN pin to a DC
voltage below 0.8V (e.g., SGND). To select pulse-skipping
mode of operation, tie the MODE/PLLIN pin to INTV CC . To
select Burst Mode operation, float the MODE/PLLIN pin.
38501fc
11
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3850IGN#TRPBF | IC REG CTRLR BUCK PWM CM 28-SSOP |
| VE-2WD-EY-F1 | CONVERTER MOD DC/DC 85V 50W |
| RCM22DTAH | CONN EDGECARD 44POS R/A .156 SLD |
| VE-2WB-EY-F4 | CONVERTER MOD DC/DC 95V 50W |
| VE-2WB-EY-F3 | CONVERTER MOD DC/DC 95V 50W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3851AEGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 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 |
| LTC3851AEGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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) |
| LTC3851AEMSE#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:- 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 |
| LTC3851AEMSE#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) |
| LTC3851AEMSE-1#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) |
发布紧急采购，3分钟左右您将得到回复。