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参数资料
| 型号： | LTC3729EUH |
| 厂商： | Linear Technology |
| 文件页数： | 17/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 73 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 590kHz |
| 占空比： | 99.5% |
| 电源电压： | 4 V ~ 36 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： | 32-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3729
APPLICATIONS INFORMATION
OPTIONAL EXTV CC CONNECTION
5V < V SEC < 7V +
C IN
LTC3729 V IN
TG1
EXTV CC N-CH
SW1
BG1
V IN
1N4148
6.8V
T1
R SENSE
V SEC
+
+
1mF
V OUT
C OUT
EXTV CC
LTC3729
C IN
V IN
TG1
SW1
BG1
+
N-CH
V IN
BAT85
L1
0.22μF
VN2222LL
R SENSE
+
+
1μF
BAT85
BAT85
V OUT
C OUT
PGND
N-CH
3729 F05a
PGND
N-CH
3729 F05b
V OUT = 0.8V ? 1 +
Figure5a.SecondaryOutputLoopandEXTV CC Connection
gate?source of the desired MOSFET. This enhances the
MOSFET and turns on the topside switch. The switch node
voltage, SW, rises to V IN and the BOOST pin rises to V IN +
V INTVCC . The value of the boost capacitor C B needs to be
30 to 100 times that of the total input capacitance of the
topside MOSFET(s). The reverse breakdown of D B must
be greater than V IN(MAX) .
The final arbiter when defining the best gate drive amplitude
level will be the input supply current. If a change is made
that decreases input current, the efficiency has improved.
If the input current does not change then the efficiency
has not changed either.
Differential Amplifier/Output Voltage
The LTC3729 has a true remote voltage sense capablity.
The sensing connections should be returned from the load
back to the differential amplifier’s inputs through a common,
tightly coupled pair of PC traces. The differential amplifier
rejects common mode signals capacitively or inductively
radiated into the feedback PC traces as well as ground
loop disturbances. The differential amplifier output signal
is divided down and compared with the internal precision
0.8V voltage reference by the error amplifier.
The differential amplifier utilizes a set of internal preci?
sion resistors to enable precision instrumentation?type
measurement of the output voltage. The output is an NPN
emitter follower without any internal pull?down current.
A DC resistive load to ground is required in order to sink
Figure 5b. Capacitive Charge Pump for EXTV CC
current. The output voltage is set by an external resistive
divider according to the following formula:
? R1 ?
?
? R2 ?
where R1 and R2 are defined in the Functional Diagram.
Soft-Start/Run Function
The RUN/SS pin provides three functions: 1) Run/Shut?
down, 2) soft?start and 3) a defeatable short?circuit latchoff
timer. Soft?start reduces the input power sources’ surge
currents by gradually increasing the controller’s current
limit I TH(MAX) . The latchoff timer prevents very short, ex?
treme load transients from tripping the overcurrent latch.
A small pull?up current (>5μA) supplied to the RUN/SS
pin will prevent the overcurrent latch from operating.
The following explanation describes how the functions
operate.
An internal 1.2μA current source charges up the C SS
capacitor. When the voltage on RUN/SS reaches 1.5V, the
controller is permitted to start operating. As the voltage on
RUN/SS increases from 1.5V to 3.0V, the internal current
limit is increased from 25mV/R SENSE to 75mV/R SENSE .
The output current limit ramps up slowly, taking an ad?
ditional 1.4μs/μF to reach full current. The output current
thus ramps up slowly, reducing the starting surge current
required from the input power supply. If RUN/SS has been
3729fb
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3729EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC3729EUH#TR | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3729EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3729LEUH-6 | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC3729LEUH-6#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
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