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参数资料
| 型号： | LTC3775EUD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/34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
Since the current limit comparator contains leading edge
blanking, an external RC ?lter is not required for proper
operation. However, an external ?lter can be designed by
adding a capacitor across the SENSE and I LIMT pins (C F
in Figure 7a). The ?lter component should be placed close
to the SENSE and I LIMT pins.
If R DS(ON) sensing is employed, the Kelvin sense con-
nection should run from the SENSE pin and the R ILIMT
resistor to the source and drain terminals of the top power
MOSFET respectively, as shown in Figure 7b. The external
RC ?lter should not be added since the source terminal
is switching.
V IN
TO R LIMIT
R SENSE
TO SENSE PIN
3775 F06
TOP MOSFET
DRAIN
Figure 6. Kelvin SENSE Connection
for Topside Current Limiting Sensing
The bottom side current limit threshold is set by the resis-
tor, R ILIMB , from the I LIMB pin to SGND and the I LIMB pin
10μA pull-up current. The voltage at ILIMB is attenuated
5 × internally before it is applied to the input of bottom
current limit comparator, CBLIM. This voltage must be
quiet. Connect R ILIMB from the I LIMB pin to a quiet ground
near the LTC3775 SGND pin. The other input of CBLIM is
connected to the SW pin. The SW pin is also shared with
the bottom gate driver and should be connected near the
drain of the bottom MOSFET, Q B .
Pulse-Skipping Mode
The LTC3775 can operate in one of two modes selectable
with the MODE/SYNC pin: pulse-skipping mode or forced
continuous mode. Pulse-skipping mode is selected when
increased ef?ciency at light loads is desired, as shown in
Figure 8. In this mode, the bottom MOSFET is turned off
when inductor current reverses in order to minimize the
ef?ciency loss due to reverse current ?ow. As the load
current decreases (see Figure 9), the duty cycle is reduced
to maintain regulation until the minimum on-time (50ns)
is reached. When the load decreases below this point,
the LTC3775 begins to skip cycles to maintain regulation.
This reduces the frequency and improves ef?ciency by
minimizing gate charge losses.
In forced continuous mode, the bottom MOSFET is always
V IN
LTC3775
I LIMIT
C IN
R LIMIT
C F
V IN
R SENSE
on when the top MOSFET is off, allowing the inductor cur-
rent to reverse at low currents. This mode is less ef?cient
due to switching, but has the advantages of better transient
SENSE
TG
3775 F07a
SW
100
90
80
70
V IN = 12V
V OUT = 1.2V
SW FREQ = 500kHz
FRONT PAGE CIRCUIT
Figure 7a. External Filter for Topside Current Sensing
60
50
40
PULSE-SKIPPING
MODE
V IN
LTC3775
I LIMIT
C IN
R LIMIT
V IN
30
20
10
CONTINUOUS
MODE
TG
Q T
0
0.01
0.1
1 10
100
SENSE
LOAD CURRENT (A)
3775 F07b
SW
3775 F08
Figure 7b. Kelvin Connection for Topside R DS(ON) Sensing
Figure 8. Ef?ciency in Pulse-Skipping/Forced Continuous Modes
3775fa
15
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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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