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参数资料
| 型号： | LTC3736-2EUF#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, PQCC24 |
| 封装： | 4 X 4 MM, LEAD FREE, PLASTIC, QFN-24 |
| 文件页数： | 8/28页 |
| 文件大小： | 344K |
| 代理商： | LTC3736-2EUF#TRPBF |
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LTC3736-2
16
37362fb
APPLICATIONS INFORMATION
Operating Frequency and Synchronization
The choice of operating frequency, fOSC, is a trade-off
between efciency and component size. Low frequency
operation improves efciency by reducing MOSFET
switching losses, both gate charge loss and transition
loss. However, lower frequency operation requires more
inductance for a given amount of ripple current.
The internal oscillator for each of the LTC3736-2’s control-
lers runs at a nominal 550kHz frequency when the PLLLPF
pin is left oating and the SYNC/FCB pin is a DC low or
high. Pulling the PLLLPF to VIN selects 750kHz operation;
pulling the PLLLPF to GND selects 300kHz operation.
Alternatively, the LTC3736-2 will phase-lock to a clock
signal applied to the SYNC/FCB pin with a frequency be-
tween 250kHz and 850kHz (see Phase-Locked Loop and
Frequency Synchronization).
Inductor Value Calculation
Given the desired input and output voltages, the inductor
value and operating frequency fOSC directly determine the
inductor’s peak-to-peak ripple current:
I
V
VV
fL
RIPPLE
OUT
IN
OUT
OSC
=
–
Lower ripple current reduces core losses in the inductor,
ESR losses in the output capacitors, and output voltage
ripple. Thus, highest efciency operation is obtained at
low frequency with a small ripple current. Achieving this,
however, requires a large inductor.
A reasonable starting point is to choose a ripple current
that is about 40% of IOUT(MAX). Note that the largest ripple
current occurs at the highest input voltage. To guarantee
that ripple current does not exceed a specied maximum,
the inductor should be chosen according to:
L
VV
fI
V
IN
OUT
OSC
RIPPLE
OUT
IN
≥
–
Inductor Core Selection
Once the inductance value is determined, the type of in-
ductor must be selected. Core loss is independent of core
size for a xed inductor value, but it is very dependent
on inductance selected. As inductance increases, core
losses go down. Unfortunately, increased inductance
requires more turns of wire and therefore copper losses
will increase.
Ferrite designs have very low core loss and are preferred
at high switching frequencies, so design goals can con-
centrate on copper loss and preventing saturation. Ferrite
core material saturates “hard,” which means that induc-
tance collapses abruptly when the peak design current is
exceeded. This results in an abrupt increase in inductor
ripple current and consequent output voltage ripple. Do
not allow the core to saturate!
Schottky Diode Selection (Optional)
The Schottky diodes D1 and D2 in Figure 16 conduct
current during the dead time between the conduction of
the power MOSFETs . This prevents the body diode of the
bottom N-channel MOSFET from turning on and storing
charge during the dead time, which could cost as much as
1% in efciency. A 1A Schottky diode is generally a good
size for most LTC3736-2 applications, since it conducts
a relatively small average current. Larger diodes result in
additional transition losses due to their larger junction
capacitance. This diode may be omitted if the efciency
loss can be tolerated.
CIN and COUT Selection
The selection of CIN is simplied by the 2-phase architec-
ture and its impact on the worst-case RMS current drawn
through the input network (battery/fuse/capacitor). It can be
shown that the worst-case capacitor RMS current occurs
when only one controller is operating. The controller with
the highest (VOUT)(IOUT) product needs to be used in the
formula below to determine the maximum RMS capacitor
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PDF描述 |
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| LTC3736-2EGN#PBF | SWITCHING CONTROLLER, PDSO24 |
| LTC3785EUF-1#TRPBF | 3 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PQCC24 |
| LTC3785EUF-1#PBF | 3 A SWITCHING REGULATOR, 650 kHz SWITCHING FREQ-MAX, PQCC24 |
| LTC3823EUH | 4 A SWITCHING CONTROLLER, 200 kHz SWITCHING FREQ-MAX, PQCC32 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| LTC3736EGN#TR | 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#TRPBF | 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® 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-1 | 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: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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