参数资料
| 型号： | LTC3735EUHF |
| 厂商： | Linear Technology |
| 文件页数： | 12/32页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR DC/DC 2PH HI EFF 38-QFN |
| 标准包装： | 52 |
| 应用： | 控制器，Intel 移动式 CPU |
| 输出数： | 1 |
| 输出电压： | 0.7 V ~ 1.71 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 38-WFQFN 裸露焊盘 |
| 供应商设备封装： | 38-QFN（5x7） |
| 包装： | 管件 |
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页当前第12页第13页第14页第15页第16页第17页第18页第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
LTC3735
APPLICATIONS INFORMATION
V OUT ? V OUT ?
? ? 1 ? V
? I L = ?
The basic LTC3735 application circuit is shown in
Figure?1 on the first page of this data sheet. External com-
ponent selection begins with the selection of the inductors
based on ripple current requirements and continues with
the current sensing resistors using the calculated peak
inductor current and/or maximum current limit. Next, the
power MOSFETs, D1 and D2 are selected. The operating
frequency and the inductor are chosen based mainly on
the amount of ripple current. Finally, C IN is selected for its
ability to handle the input ripple current (that PolyPhase ?
operation minimizes) and C OUT is chosen with low enough
ESR to meet the output ripple voltage and load step
specifications (also minimized with PolyPhase). Current
mode architecture provides inherent current sharing be-
tween output stages. The circuit shown in Figure?1 can
be configured for operation up to an input voltage of 28V
(limited by the external MOSFETs). Current mode control
allows the ability to connect the two output stages to two
different input power supply rails. A heavy output load
can take some power from each input supply according
to the selection of the R SENSE resistors.
R SENSE Selection For Output Current
R SENSE1,2 are chosen based on the required peak output
current. The LTC3735 current comparator has a maximum
threshold of 72mV/R SENSE and an input common mode
range of SGND to PV CC . The current comparator threshold
sets the peak inductor current, yielding a maximum aver-
age output current I MAX equal to the peak value less half
the peak-to-peak ripple current, ?I L .
Assuming a common input power source for each out-
put stage and allowing a margin for variations in the
LTC3735 and external component values yields:
R SENSE = 2(40mV/I MAX )
Operating Frequency
The LTC3735 uses a constant frequency architecture with
the frequency determined by an internal capacitor. This
capacitor is charged by a fixed current plus an additional
current which is proportional to the DC voltage applied
to the FREQSET pin. The FREQSET voltage is internally
set to 1.2V. It is recommended that this pin is actively
biased with a resistor divider to prevent noise getting
into the system.
A graph for the voltage applied to the FREQSET pin vs fre-
quency is given in Figure?2. As the operating frequency is
increased the gate drive and switching losses will be higher,
reducing efficiency (see Efficiency Considerations). The
maximum switching frequency is approximately 550kHz.
600
550
500
450
400
350
300
250
200
150
100
0 0.5 1.0 1.5 2.0 2.5 3.0
FREQSET PIN VOLTAGE (V)
3735 F02
Figure 2. Operating Frequency vs V FREQSET
Inductor Value Calculation and Output Ripple Current
The operating frequency and inductor selection are inter-
related in that higher operating frequencies allow the use
of smaller inductor and capacitor values. So why would
anyone ever choose to operate at lower frequencies with
larger components? The answer is efficiency. A higher
frequency generally results in lower efficiency because
MOSFET gate charge and transition losses increase
directly with frequency. In addition to this basic tradeoff,
the effect of inductor value on ripple current and low cur-
rent operation must also be considered. The PolyPhase
approach reduces both input and output ripple currents
while optimizing individual output stages to run at a lower
fundamental frequency, enhancing efficiency.
The inductor value has a direct effect on ripple current.
The inductor ripple current ?I L , decreases with higher
inductance or frequency and increases with higher V IN :
fL IN ?
where f is the individual output stage operating frequency.
3735fa
12
相关PDF资料 |
PDF描述 |
|---|---|
| RMM36DRUS | CONN EDGECARD 72POS DIP .156 SLD |
| LTC3733CUHF-1#TRPBF | IC CTRLR BUCK 3PH AMD CPU 38-QFN |
| HSM22DSAN | CONN EDGECARD 44POS R/A .156 SLD |
| HMM22DSAN | CONN EDGECARD 44POS R/A .156 SLD |
| LTC3733CUHF-1#TR | IC CTRLR BUCK 3PH AMD CPU 38-QFN |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3735EUHF#PBF | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:2,000 系列:- 应用:控制器，DSP 输入电压:4.5 V ~ 25 V 输出数:2 输出电压:最低可调至 1.2V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:30-TFSOP（0.173"，4.40mm 宽） 供应商设备封装:30-TSSOP 包装:带卷 (TR) |
| LTC3735EUHF#TR | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3735EUHF#TRPBF | 功能描述:IC CTRLR DC/DC 2PH HI EFF 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 标准包装:43 系列:- 应用:控制器，Intel VR11 输入电压:5 V ~ 12 V 输出数:1 输出电压:0.5 V ~ 1.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:48-VFQFN 裸露焊盘 供应商设备封装:48-QFN（7x7） 包装:管件 |
| LTC3736EGN | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP 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: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) |
| LTC3736EGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 24-SSOP 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 |
发布紧急采购，3分钟左右您将得到回复。