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参数资料
| 型号： | LT3957EUHE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG ADJ 36VQFN |
| 特色产品： | LT?3957/LT?3958 Converters |
| 标准包装： | 61 |
| 类型： | 升压（升压），反相，回扫，Sepic |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.6 V ~ 40 V |
| 输入电压： | 3 V ~ 40 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 1MHz |
| 电流 - 输出： | 5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 36-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 36-QFN-EP（6x5） |
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LT3957
APPLICATIONS INFORMATION
INTV CC Regulator Bypassing and Operation
An internal, low dropout (LDO) voltage regulator produces
the 5.2V INTV CC supply which powers the gate driver, as
shown in Figure 1. The LT3957 contains an undervoltage
lockout comparator A8 for the INTV CC supply. The INTV CC
undervoltage (UV) threshold is 2.7V (typical), with 0.1V
hysteresis, to ensure that the internal MOSFET has suf-
?cient gate drive voltage before turning on. When INTV CC
is below the UV threshold, the internal power switch will
be turned off and the soft-start operation will be triggered.
The logic circuitry within the LT3957 is also powered from
the internal INTV CC supply.
The INTV CC regulator must be bypassed to SGND imme-
diately adjacent to the IC pins with a minimum of 4.7μF
ceramic capacitor. Good bypassing is necessary to supply
the high transient currents required by the MOSFET gate
driver.
In an actual application, most of the IC supply current is
used to drive the gate capacitance of the internal power
MOSFET. The on-chip power dissipation can be signi?cant
when the internal power MOSFET is being driven at a high
frequency and the V IN voltage is high.
An effective approach to reduce the power consumption of
the internal LDO for gate drive and to improve the ef?ciency
is to tie the INTV CC pin to an external voltage source high
In SEPIC or ?yback applications, the INTV CC pin can be
connected to the output voltage V OUT through a blocking
diode, as shown in Figure 2, if V OUT meets the following
conditions:
1. V OUT < V IN (pin voltage)
2. V OUT < 8V
A resistor R VCC can be connected, as shown in Figure 2, 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 SGND pins.
If LT3957 operates at a low V IN and high switching fre-
quency, the voltage drop across the drain and the source of
the LDO PMOS (M2 in Figure 1) could push INTV CC to be
below the UV threshold. To prevent this from happening,
the INTV CC pin can be shorted directly to the V IN pin. V IN
must not exceed the INTV CC Absolute Maximum Rating
(8V). In this condition, the internal LDO will be turned off
and the gate driver will be powered directly from V IN . It is
recommended that INTV CC pin be shorted to the V IN pin if
V IN is lower than 3.5V at 1MHz switching frequency, or V IN
is lower than 3.2V at 100kHz switching frequency. With
the INTV CC pin shorted to V IN , however, a small current
(around 16μA) will load the INTV CC in shutdown mode.
enough to turn off the internal LDO regulator.
INTV CC
D VCC
R VCC
V OUT
LT3957
C VCC
4.7μF
SGND
3957 F02
Figure 2. Connecting INTV CC to V OUT
3957f
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3957EUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| LT3957IUHE#PBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3957IUHE#TRPBF | 功能描述:IC REG MULTI CONFIG ADJ 36VQFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V，1.5V，1.8V，2.5V 输入电压:2.7 V ~ 20 V PWM 型:- 频率 - 开关:- 电流 - 输出:50mA 同步整流器:是 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 包装:带卷 (TR) 供应商设备封装:10-MSOP 裸露焊盘 |
| LT3957IUHEPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| LT3957IUHETRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
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