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| 型号： | LT3579EFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/40页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG SYNC 20TSSOP |
| 标准包装： | 74 |
| 类型： | 升压（升压），反相，回扫，Sepic |
| 输出数： | 1 |
| 输入电压： | 2.5 V ~ 16 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 2.5MHz |
| 电流 - 输出： | 6A |
| 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： | 20-TSSOP（0.173"，4.40mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 20-TSSOP-EP |
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LT3579/LT3579-1
OPERATION
+
OPERATION – OVERVIEW
The LT3579 uses a constant-frequency, current mode
control scheme to provide excellent line and load regulation.
The part’s undervoltage lockout (UVLO) function, together
with soft-start and frequency foldback, offers a controlled
means of starting up. Fault features are incorporated in
the LT3579 to aid in the detection of output shorts, over-
voltage, and overtemperature conditions. Refer to the Block
Diagram (Figure 1) and the State Diagram (Figure 2) for
the following description of the part’s operation.
V IN
R UVLO1
R UVLO2
(OPTIONAL)
V IN
1.33V –
SHDN
11.6μA
AT 1.33V
GND
Figure 3. Configurable UVLO
ACTIVE/
LOCKOUT
35791 F03
? ? R UVLO2
? ?
OPERATION–START-UP
Several functions are provided to enable a very clean
start-up for the LT3579.
Precise Turn-On Voltage
The SHDN pin compares to an internal voltage reference to
give a precise turn on voltage level. Taking the SHDN pin
above 1.33V (typical) enables the part. Taking the SHDN pin
below 0.3V shuts down the chip, resulting in extremely low
quiescent current. The SHDN pin has 30mV of hysteresis
to protect against glitches and slow ramping.
Undervoltage-Lockout (UVLO)
The SHDN pin can also be used to create a configurable
UVLO. The UVLO function sets the turn on/off of the LT3579
at a desired input voltage (VIN UVLO ). Figure 3 shows how
a resistor divider (or single resistor) from V IN to the SHDN
pin can be used to set VIN UVLO . R UVLO2 is optional. It may
be left out, in which case set it to infinite in the equation
below. For increased accuracy, set R UVLO2 ≤ 10k?. Pick
R UVLO1 as follows:
VIN UVLO – 1.33V
R UVLO1 =
? 1.33V ?
? ? + 11.6μA
The LT3579 also has internal UVLO circuitry that disables
the chip when V IN < 2.3V (typical).
Soft-Start of Switch Current
The soft-start circuitry provides for a gradual ramp-up of
the switch current (refer to Commanded Switch Current vs.
SS in Typical Performance Characteristics). When the part
is brought out of shutdown, the external SS capacitor is
first discharged which resets the states of the logic circuits
in the chip. Then an integrated 250k resistor pulls the SS
pin to ~1.8V at a ramp rate set by the external capacitor
connected to the pin. Once SS gets to 1.8V, the CLKOUT
pin is enabled, and an internal regulator pulls the pin up
quickly to ~2.1V. Typical values for the external soft-start
capacitor range from 100nF to 1μF.
Soft-Start of External PMOS (if used)
The soft-start circuitry also gradually ramps up the GATE
pin pull-down current which allows an external PMOS
to slowly turn on (M1 in Block Diagram). The GATE pin
current increases linearly with SS voltage, with a maximum
current of 933μA when the SS voltage gets above 500mV.
Note that if the GATE pin voltage is less than 2V for SS
voltages exceeding 500mV, then the GATE pin impedance
to ground is 2k?. The soft turn on of the external PMOS
helps limit inrush current at start-up, making hot plugs
of the LT3579 feasible and safe.
35791f
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3579EFE-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:6A Boost/Inverting DC/DC Converter with Fault Protection |
| LT3579EUFD#PBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
| LT3579EUFD#TRPBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
| LT3579EUFD-1#PBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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 |
| LT3579EUFD-1#TRPBF | 功能描述:IC REG MULTI CONFIG SYNC 20QFN 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:20 系列:SIMPLE SWITCHER® 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:12V 输入电压:4 V ~ 60 V PWM 型:电压模式 频率 - 开关:52kHz 电流 - 输出:1A 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 包装:管件 供应商设备封装:16-DIP 其它名称:*LM2575HVN-12LM2575HVN-12 |
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