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参数资料
| 型号： | LTC3836EUFD#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 825kHz |
| 占空比： | 97% |
| 电源电压： | 2.75 V ~ 4.5 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) |
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LTC3836
OPERATION
Main Control Loop
(Refer to Functional Diagram)
source), the EAMP regulates the V FB1 proportionally
The LTC3836 uses a constant-frequency, current mode
architecture with the two controllers operating 180 degrees
out-of-phase. During normal operation, the top external
power MOSFET is turned on when the clock for its chan-
nel sets the RS latch, and turned off when the current
comparator (I CMP ) resets the latch. The peak inductor
current at which I CMP resets the RS latch is determined
by the voltage on the I TH pin, which is driven by the output
of the error ampli?er (EAMP). The V FB pin receives the
output voltage feedback signal from an external resistor
divider. This feedback signal is compared to the internal
0.6V reference voltage by the EAMP. When the load current
increases, it causes a slight decrease in V FB relative to the
0.6V reference, which in turn causes the I TH voltage to
increase until the average inductor current matches the
new load current. While the top N-channel MOSFET is off,
the bottom N-channel MOSFET is turned on until either
the inductor current starts to reverse, as indicated by the
current reversal comparator, I RCMP , or the beginning of
the next cycle.
Shutdown, Soft-Start and Tracking Start-Up
(RUN/SS and TRACK/SS2 Pins)
The LTC3836 is shut down by pulling the RUN/SS pin
low. In shutdown, all controller functions are disabled and
the chip draws only 6.5μA. The TG and BG outputs are
held low (off) in shutdown. Releasing RUN/SS allows an
internal 0.65μA current source to charge up the RUN/SS
pin. When the RUN/SS pin reaches 0.65V, the LTC3836’s
two controllers are enabled.
The start-up of V OUT1 is controlled by the LTC3836’s
internal soft-start. During soft-start, the error ampli?er
EAMP compares the feedback signal V FB1 to the internal
soft-start ramp (instead of the 0.6V reference), which rises
linearly from 0V to 0.6V in about 1ms. This allows the
output voltage to rise smoothly from 0V to its ?nal value,
while maintaining control of the inductor current.
The 1ms soft-start time can be increased by con-
necting the optional external soft-start capacitor C SS
between the RUN/SS and SGND pins. As the RUN/SS
pin continues to rise linearly from approximately 0.65V
to 1.3V (being charged by the internal 0.65μA current
from 0V to 0.6V.
The start-up of V OUT2 is controlled by the voltage on the
TRACK/SS2 pin. When the voltage on the TRACK/SS2
pin is less than the 0.6V internal reference, the LTC3836
regulates the V FB2 voltage to the TRACK/SS2 pin voltage
instead of the 0.6V reference. This allows the TRACK/SS2
pin to be used to program a soft-start by connecting an
external capacitor from the TRACK/SS2 pin to SGND.
An internal 1μA pull-up current charges this capacitor,
creating a voltage ramp on the TRACK/SS2 pin. As the
TRACK/SS2 voltage rises linearly from 0V to 0.6V (and
beyond), the output voltage V OUT2 rises smoothly from
zero to its ?nal value.
Alternatively, the TRACK/SS2 pin can be used to cause the
start-up of V OUT2 to “track” that of another supply. Typi-
cally, this requires connecting to the TRACK/SS2 pin an
external resistor divider from the other supply to ground
(see Applications Information section).
When the RUN/SS pin is pulled low to disable the
LTC3836, or when V IN drops below its undervoltage
lockout threshold, the TRACK/SS2 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 Operation (Pulse-Skipping or Continuous
Conduction) (SYNC/FCB Pin)
The LTC3836 can be enabled to enter high ef?ciency pulse-
skipping operation or forced continuous conduction mode
at low load currents. To select pulse-skipping operation, tie
the SYNC/FCB pin to a DC voltage above 0.6V (e.g., V IN ).
To select forced continuous operation, tie the SYNC/FCB
to a DC voltage below 0.6V (e.g., SGND).
In forced continuous operation, the inductor current is
allowed to reverse at light loads or under large transient
conditions. The peak inductor current is determined by
the voltage on the I TH pin. The main N-channel MOSFET
is turned on every cycle (constant-frequency) regardless
of the I TH pin voltage. In this mode, the ef?ciency at light
loads is lower than in pulse-skipping operation. However,
continuous mode has the advantages of lower output ripple
and less interference with audio circuitry.
3836fb
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参数描述 |
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| LTC3838EFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3838EFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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) |
| LTC3838EUHF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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) |
| LTC3838EUHF#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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) |
| LTC3838EUHF-1#PBF | 制造商:Linear Technology 功能描述:IC REG CTRLR BUCK PWM CM 38QFN 制造商:Linear Technology 功能描述:BUCK DUAL CNTRL 4.5-38V 2MHZ 38QFN 制造商:Linear Technology 功能描述:BUCK, DUAL, CNTRL, 4.5-38V, 2MHZ, 38QFN 制造商:Linear Technology 功能描述:DC-DC CONTROLLER, DUAL, BUCK, ADJ, QFN-38, Primary Input Voltage:38V, No. of Outputs:2, Output Current:25A, No. of Pins:38, Operating Temperature Min:-40C, Operating Temperature Max:125C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes 制造商:Linear Technology 功能描述:DP-SWREG/Controller, Dual, Fast, Accurate Step-Down Controller with Differential |
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