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参数资料
| 型号： | LTC3775EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/34页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 16-QFN |
| 标准包装： | 121 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 80% |
| 电源电压： | 4.5 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 |
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LTC3775
APPLICATIONS INFORMATION
After the calculations have been completed, it is impor-
tant to measure the gate drive waveforms and the gate
driver supply voltage (INTV CC to PGND) over all operating
conditions (low V IN , nominal V IN and high V IN , as well
as from light load to full load) to ensure adequate power
MOSFET enhancement. Consult the power MOSFET data
sheet to determine the actual R DS(ON) for the measured
V GS , and verify your thermal calculations by measuring
the component temperatures using an infrared camera
TG
10V/DIV
V SW
10V/DIV
or thermal probe.
V IN = 28V
20ns/DIV
3775 F11
Operation at High Supply Voltage
At high input voltages, the LTC3775’s internal LDO can
dissipate a signi?cant amount of power, which could
cause the maximum junction temperature to be exceeded.
Conditions such as a high operating frequency, or the use
of more than one power MOSFET in parallel, could push
the junction temperature rise to high levels. To prevent
the maximum junction temperature from being exceeded,
the input supply current must be checked while operating
in continuous conduction mode at maximum V IN . See
the Thermal Considerations section for calculation of the
maximum junction temperature.
Low Duty Cycle Operation
V OUT = 0.6V
LOAD = 1A
MODE/SYNC = 0V
SW FREQ = 1MHz
Figure 11. Minimum On-Time Waveforms
in Forced Continuous Mode
TG
10V/DIV
V SW
10V/DIV
The LTC3775 uses a leading edge modulation architec-
V IN = 28V
V OUT = 0.6V
20ns/DIV
3775 F12
ture. Because the top MOSFET turns on when the PWM
comparator trips, the top MOSFET minimum on-time
is not dependent on the propagation delay of the PWM
comparator; it is only limited by the internal delays of the
gate drivers and the rise/fall time of the power MOSFET
gate. This allows the LTC3775 to operate in very low duty
cycle applications with a large step-down ratio. Figure 11
shows minimum on-time waveforms for forced continuous
mode operation.
If pulse-skipping mode is selected, the LTC3775 allows
the controller to skip pulses at light load, thereby reducing
switching losses and improving the ef?ciency. Figure 12
shows waveforms of the minimum on-time in pulse-skip-
ping mode.
LOAD = 1A
MODE/SYNC = INTV CC
SW FREQ = 1MHz
Figure 12. Minimum On-Time Waveforms
in Pulse-Skipping Mode
is 200ns for R DS(ON) sensing and 100ns when a sense
resistor is used. For TG on-times smaller than the topside
blanking times, the LTC3775 relies on the bottom current
limit comparator, CBLIM, to monitor the inductor current.
If CBLIM trips, the LTC3775 starts to skip pulses and at
the same time pulls down the soft-start capacitor to limit
the duty cycle. If V OUT drops suf?ciently, the TG on-time
can increase enough to turn on CTLIM and limit the peak
inductor current. The minimum on-time of the application
circuit can be calculated at maximum V IN :
f SW IN ( MAX )
IftheTGon-timeislessthantheblankingtimeofthetopside
current limit comparator, CTLIM, the topside comparator
never trips during normal operation. The blanking time
t ON ( MIN ) =
V OUT
? V
3775fa
18
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相关代理商/技术参数 |
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| LTC3775IMSE#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 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) |
| LTC3775IMSE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 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) |
| LTC3775IUD#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 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) |
| LTC3775IUD#TRPBF | 功能描述:IC REG CTRLR BUCK PWM VM 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) |
| LTC3776EGN | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 2.75V to 9.8V Input 24-Pin SSOP N |
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