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| 型号： | LTC3703IGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/34页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM VM 16-SSOP |
| 标准包装： | 100 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 330kHz |
| 占空比： | 96% |
| 电源电压： | 9.3 V ~ 15 V |
| 降压： | 是 |
| 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： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
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LTC3703
OPERATION
(Refer to Functional Diagram)
side MOSFETs can occur. To prevent this from occurring,
the bottom driver return is brought out as a separate pin
(BGRTN) so that a negative supply can be used to reduce
the effect of the Miller pull-up. For example, if a –2V sup-
ply is used on BGRTN, the switch node dV/dt could pull
the gate up 2V before the V GS of the bottom MOSFET has
more than 0V across it.
DRV CC V IN
duty cycle control set to 0%. As C SS continues to charge,
the duty cycle is gradually increased, allowing the output
voltage to rise. This soft-start scheme smoothly ramps the
output voltage to its regulated value with no overshoot.
The RUN/SS voltage will continue ramping until it reaches
an internal 4V clamp. Then the MIN feedback comparator
is enabled and the LTC3703 is in full operation. When the
RUN/SS is low, the supply current is reduced to 50μA.
LTC3703
DRV CC
BOOST
D B
+
C IN
V OUT
BGRTN
0V TO –5V
TG
SW
BG
C B
MT
MB
L
+
3703 F03
V OUT
C OUT
0V
4V
3V
V RUN/SS
1.4V
0.9V
SHUTDOWN START-UP
NORMAL OPERATION
MIN COMPARATOR ENABLED
OUTPUT VOLTAGE
IN REGULATION
RUN/SS SOFT-STARTS
OUTPUT VOLTAGE AND
INDUCTOR CURRENT
CURRENT
LIMIT
ENABLE DOWN MODE
Figure3.FloatingTGDriverSupplyandNegativeBGReturn
Constant Frequency
The internal oscillator can be programmed with an external
resistor connected from f SET to ground to run between
100kHz and 600kHz, thereby optimizing component size,
efficiency, and noise for the specific application. The internal
oscillator can also be synchronized to an external clock
applied to the MODE/SYNC pin and can lock to a frequency
in the 100kHz to 600kHz range. When locked to an external
clock, pulse-skip mode operation is automatically disabled.
Constant frequency operation brings with it a number of
benefits: inductor and capacitor values can be chosen for
a precise operating frequency and the feedback loop can
be similarly tightly specified. Noise generated by the circuit
will always be at known frequencies. Subharmonic oscil-
lation and slope compensation, common headaches with
constant frequency current mode switchers, are absent in
voltage mode designs like the LTC3703.
Shutdown/Soft-Start
The main control loop is shut down by pulling RUN/SS
pin low. Releasing RUN/SS allows an internal 4μA current
source to charge the soft-start capacitor, C SS . When C SS
reaches 0.9V, the main control loop is enabled with the
MINIMUM
0V DUTY CYCLE
LTC3703 POWER
3703 F04
Figure 4. Soft-Start Operation in Start-Up and Current Limit
Current Limit
The LTC3703 includes an onboard current limit circuit that
limits the maximum output current to a user-programmed
level. It works by sensing the voltage drop across the
bottom MOSFET and comparing that voltage to a user-
programmed voltage at the I MAX pin. Since the bottom
MOSFET looks like a low value resistor during its on-time,
the voltage drop across it is proportional to the current
flowing in it. In a buck converter, the average current in
the inductor is equal to the output current. This current
also flows through the bottom MOSFET during its on-time.
Thus by watching the drain-to-source voltage when the
bottom MOSFET is on, the LTC3703 can monitor the output
current. The LTC3703 senses this voltage and inverts it to
allow it to compare the sensed voltage (which becomes
more negative as peak current increases) with a positive
voltage at the I MAX pin. The I MAX pin includes a 12μA
pull-up, enabling the user to set the voltage at I MAX with
a single resistor (R IMAX ) to ground. See the Current Limit
Programming section for R IMAX selection.
3703fc
10
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相关代理商/技术参数 |
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| LTC3704EMS | 功能描述:IC REG CTRLR INV PWM CM 10-MSOP RoHS:否 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) |
| LTC3704EMS#PBF | 功能描述:IC REG CTRLR INV 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:- 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 |
| LTC3704EMS#PBF | 制造商:Linear Technology 功能描述:IC, DC/DC CONTROLLER, 300kHz, MSOP-10 |
| LTC3704EMS#TR | 功能描述:IC REG CTRLR INV PWM CM 10-MSOP RoHS:否 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) |
| LTC3704EMS#TRPBF | 功能描述:IC REG CTRLR INV 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) |
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