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参数资料
| 型号： | LT3690MPUFE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 19/30页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 4A 26QFN |
| 标准包装： | 61 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 20 V |
| 输入电压： | 3.9 V ~ 36 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 138kHz ~ 1.5MHz |
| 电流 - 输出： | 4A |
| 同步整流器： | 是 |
| 工作温度： | -55°C ~ 150°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 26-WFQFN 裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 26-QFN-EP（4x6） |
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LT3690
APPLICATIONS INFORMATION
6.0
5.5
TO START
V OUT = 3.3V
L = 4.7μH
? = 600kHz
7.5
7.0
TO START
V OUT = 5V
L = 4.7μH
? = 600kHz
5.0
4.5
6.5
6.0
4.0
3.5
TO RUN
5.5
5.0
TO RUN
3.0
1
10
100
1000
10000
4.5
1
10
100
1000
10000
LOAD CURRENT (mA)
3690 F06a
LOAD CURRENT (mA)
3690 F06b
Figure 6. The Minimum Input Voltage Depends on Output Voltage, Load Current and Boost Circuit
t RAMP = SS
isalsolimitedbytheboostcircuit.Iftheinputvoltageis
ramped slowly, or the LT3690 is turned on with its EN pin
when the output is already in regulation, then the boost
capacitor may not be fully charged. Because the boost
capacitor charges with the energy stored in the inductor,
the circuit relies on some minimum load current to get the
boost circuit running properly. This minimum load depends
on the input and output voltages, and on the arrangement
of the boost circuit. The minimum load generally goes to
zero once the circuit has started. Figure 6 shows a plot of
minimum load to start and to run as a function of input
voltage. In many cases the discharged output capacitor
will present a load to the switcher, which will allow it to
start. The plots show the worst-case situation, where V IN
is ramping very slowly. For lower start-up voltage, the
boost diode can be tied to V IN ; however, this restricts the
input range to one-half of the absolute maximum rating of
the BST pin. At light loads, the inductor current becomes
discontinuous and the effective duty cycle can be very high.
This reduces the minimum input voltage to approximately
300mV above V OUT . At higher load currents, the inductor
current is continuous and the duty cycle is limited by the
maximum duty cycle of the LT3690, requiring a higher
input voltage to maintain regulation.
pin. A good value for the soft-start capacitor is C OUT /10000,
where C OUT is the value of the output capacitor.
The soft-start function limits peak input current to the circuit
during start-up. The output of the LT3690 regulates to the
lowest voltage present at either the SS pin or an internal
0.8V reference. A capacitor from the SS pin to ground is
charged by an internal 2μA current source resulting in a
linear output ramp from 0V to the regulated output volt-
age. The ramp duration is given by:
C ? 0.8V
2μA
At power-up, an internal open-collector output discharges
the SS pin. The SS pin can be left floating if the soft-start
feature is not used. The internal current sources will charge
this pin to ~2V as shown in Figure 7.
V EN
2V/DIV
V SS
1V/DIV
V OUT
2V/DIV
Soft-Start
The SS (soft-start) pin provides a soft-start function. If a
capacitor C SS is tied from the SS pin to ground, then the
internal pull-up current will generate a voltage ramp on this
I L
2A/DIV
50ms/DIV
C SS = 0.22μF
Figure 7. Soft-Start Ramp
3690 F07
3690fa
19
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相关代理商/技术参数 |
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| LT3692 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Monolithic Dual Tracking |
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| LT3692AEFE#PBF | 功能描述:IC REG BUCK ADJ 3.5A DL 38TSSOP 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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LT3692AEFE#TRPBF | 功能描述:IC REG BUCK ADJ 3.5A DL 38TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT3692AEUH#PBF | 功能描述:IC REG BUCK ADJ 3.5A DL 32QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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