- 您现在的位置：买卖IC网 > PDF目录1831 > LTC3707IGN#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC3707IGN#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 19/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 360kHz |
| 占空比： | 99.4% |
| 电源电压： | 4.5 V ~ 28 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： | 28-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页当前第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页
LTC3707
APPLICATIONS INFORMATION
R1 (MAX) = 24k ?
V OUT = 0.8V ? 1 +
= ( 1.25s / μF ) C SS
t DELAY =
1.2μA SS
Topside MOSFET Driver Supply (C B , D B )
External bootstrap capacitors C B connected to the BOOST
pins supply the gate drive voltages for the topside MOSFETs.
Capacitor C B in the functional diagram is charged though
external diode D B from INTV CC when the SW pin is low.
When one of the topside MOSFETs is to be turned on,
the driver places the C B voltage across the 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 follows. With the topside
MOSFET on, the boost voltage is above the input supply:
V BOOST = V IN + V INTVCC . The value of the boost capacitor
C B needs to be 100 times that of the total input capacitance
of the topside MOSFET(s). The reverse breakdown of the
external Schottky diode must be greater than V IN(MAX) .
When adjusting the gate drive level, the ?nal arbiter is the
total input current for the regulator. If a change is made
and the input current decreases, then the ef?ciency has
improved. If there is no change in input current, then there
is no change in ef?ciency.
Output Voltage
The LTC3707 output voltages are each set by an external
feedback resistive divider carefully placed across the output
capacitor. The resultant feedback signal is compared with
the internal precision 0.800V voltage reference by the error
ampli?er. The output voltage is given by the equation:
? R2 ?
?
? R1 ?
SENSE + /SENSE – Pins
The common mode input range of the current comparator
sense pins is from 0V to (1.1)INTV CC . Continuous linear
operation is guaranteed throughout this range allowing
output voltage setting from 0.8V to 7.7V, depending upon
the voltage applied to EXTV CC . A differential NPN input
stage is biased with internal resistors from an internal 2.4V
source as shown in the Functional Diagram. This requires
that current either be sourced or sunk from the SENSE
the V OUT resistive divider to compensate for the current
comparator’s negative input bias current. The maximum
current ?owing out of each pair of SENSE pins is:
I SENSE+ + I SENSE– = (2.4V – V OUT )/24k
Since V OSENSE is servoed to the 0.8V reference voltage,
we can choose R1 in Figure 2 to have a maximum value
to absorb this current.
? 0.8V ?
? 2.4V – V OUT ? ?
for V OUT < 2.4V
Regulating an output voltage of 1.8V, the maximum value
of R1 should be 32K. Note that for an output voltage above
2.4V, R1 has no maximum value necessary to absorb the
sense currents; however, R1 is still bounded by the V OSENSE
feedback current.
Soft-Start/Run Function
The RUN/SS1 and RUN/SS2 pins are multipurpose pins
that provide a soft-start function and a means to shut down
the LTC3707. Soft-start reduces the input power source’s
surge currents by gradually increasing the controller’s
current limit (proportional to V ITH ). This pin can also be
used for power supply sequencing.
An internal 1.2μA current source charges up the C SS ca-
pacitor . When the voltage on RUN/SS1 (RUN/SS2) reaches
1.5V, the particular 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 additional 1.25s/μF to reach full current. The
output current thus ramps up slowly, reducing the start-
ing surge current required from the input power supply.
If RUN/SS has been pulled all the way to ground there is
a delay before starting of approximately:
1.5V
C
pins depending on the output voltage. If the output voltage
is below 2.4V current will ?ow out of both SENSE pins to
the main output. The output can be easily preloaded by
t IRAMP =
3V ? 1.5V
1.2μA
C SS = ( 1.25s / μF ) C SS
3707fb
19
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3708EUH#PBF | IC REG CTRLR BUCK PWM CM 32-QFN |
| LTC3709EG#TRPBF | IC REG CTRLR BUCK PWM CM 36-SSOP |
| LTC3711EGN#TR | IC REG CTRLR BUCK PWM CM 24-SSOP |
| LTC3713EG#TR | IC REG CTRLR BUCK PWM CM 24-SSOP |
| LTC3714EG | IC STP-DWN CNTRLR W/OPAMP 28SSOP |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3708EUH | 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 |
| LTC3708EUH#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 |
| LTC3708EUH#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 |
| LTC3708EUH#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 |
| LTC3708EUHPBF | 制造商:Linear Technology 功能描述:LTC3708 dual SD tracking PS controller |
发布紧急采购，3分钟左右您将得到回复。