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| 型号： | LT3757IDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK INV 10DFN |
| 产品培训模块： | LT3757 and LT3758 - Boost, Flyback, SEPIC and Inverting Controllers |
| 标准包装： | 121 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 电源电压： | 2.9 V ~ 40 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 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： | 10-WFDFN 裸露焊盘 |
| 包装： | 管件 |
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LT3757/LT3757A
APPLICATIONS INFORMATION
Prior to lowering the operating frequency, however, be
sure to check with power MOSFET manufacturers for their
most recent low Q G , low R DS(ON) devices. Power MOSFET
manufacturing technologies are continually improving, with
newer and better performance devices being introduced
almost yearly.
An effective approach to reduce the power consumption
of the internal LDO for gate drive is to tie the INTV CC pin
to an external voltage source high enough to turn off the
internal LDO regulator.
If the input voltage V IN does not exceed the absolute
maximum rating of both the power MOSFET gate-source
voltage (V GS ) and the INTV CC overvoltage lockout threshold
voltage (17.5V), the INTV CC pin can be shorted directly
to the V IN pin. In this condition, the internal LDO will be
turned off and the gate driver will be powered directly
from the input voltage, V IN . With the INTV CC pin shorted to
V IN , however, a small current (around 16μA) will load the
INTV CC in shutdown mode. For applications that require
the lowest shutdown mode input supply current, do not
connect the INTV CC pin to V IN .
In SEPIC or flyback applications, the INTV CC pin can be
connected to the output voltage V OUT through a blocking
diode, as shown in Figure 3, if V OUT meets the following
conditions:
1. V OUT < V IN (pin voltage)
2. V OUT < 17.5V
3. V OUT < maximum V GS rating of power MOSFET
A resistor R VCC can be connected, as shown in Figure 3, to
limit the inrush current from V OUT . Regardless of whether
or not the INTV CC pin is connected to an external voltage
source, it is always necessary to have the driver circuitry
bypassed with a 4.7μF low ESR ceramic capacitor to
ground immediately adjacent to the INTV CC and GND pins.
Operating Frequency and Synchronization
The choice of operating frequency may be determined
by on-chip power dissipation, otherwise it is a trade-off
between efficiency and component size. Low frequency
operation improves efficiency by reducing gate drive cur-
rent and MOSFET and diode switching losses. However,
lower frequency operation requires a physically larger
inductor. Switching frequency also has implications for
loop compensation. The LT3757 uses a constant-frequency
architecture that can be programmed over a 100kHz to
1000kHz range with a single external resistor from the
RT pin to ground, as shown in Figure 1. The RT pin must
have an external resistor to GND for proper operation of
the LT3757. A table for selecting the value of R T for a given
operating frequency is shown in Table 1.
Table 1. Timing Resistor (R T ) Value
OSCILLATOR FREQUENCY (kHz) R T (kΩ)
100 140
200 63.4
300 41.2
400 30.9
500 24.3
600 19.6
700 16.5
800 14
900 12.1
1000 10.5
The operating frequency of the LT3757 can be synchronized
to an external clock source. By providing a digital clock
signal into the SYNC pin, the LT3757 will operate at the
SYNC clock frequency. If this feature is used, an R T resistor
should be chosen to program a switching frequency 20%
slower than SYNC pulse frequency. The SYNC pulse should
have a minimum pulse width of 200ns. Tie the SYNC pin
to GND if this feature is not used.
LT3757
INTV CC
D VCC
R VCC
V OUT
C VCC
4.7μF
GND
3757 F03
Figure 3. Connecting INTV CC to V OUT
3757afd
11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3757IDD-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Controller |
| LT3757IMSE | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Flyback Controller 2.9V to 40V Input 10-Pin MSOP EP 制造商:Linear Technology 功能描述:CONTROLLER |
| LT3757IMSE#PBF | 功能描述:IC REG CTRLR PWM CM 10-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) |
| LT3757IMSE#TRPBF | 功能描述:IC REG CTRLR PWM CM 10-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) |
| LT3757IMSEPBF | 制造商:Linear Technology 功能描述:Boost Flyback SEPIC Controller MSOP10EP |
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