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| 型号： | LTC3814EFE-5#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 16-TSSOP |
| 标准包装： | 95 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 1MHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 55 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： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3814-5
APPLICATIONS INFORMATION
I O(MAX) Δ I L
1 ? D MAX
I L(SAT) ≥ +
Minimum On-Time and Dropout Operation
The minimum on-time t ON(MIN) is the smallest amount of
time that the LTC3814-5 is capable of turning on the bottom
MOSFET, tripping the current comparator and turning the
MOSFET back off. This time is generally about 350ns. The
minimum on-time limit imposes a minimum duty cycle
of t ON(MIN) /(t ON(MIN) + t OFF ). If the minimum duty cycle is
reached, due to a rising input voltage for example, then
the output will rise out of regulation. The maximum input
voltage to avoid dropout is:
The required saturation of the inductor should be chosen
to be greater than the peak inductor current:
2
Once the value for L is known, the type of inductor must
be selected. High ef?ciency converters generally cannot
afford the core loss found in low cost powdered iron cores,
forcing the use of more expensive ferrite, molypermalloy
or Kool Mμ ? cores. A variety of inductors designed for
V IN(MAX) = V OUT
t OFF
t ON(MIN) + t OFF
high current, low voltage applications are available from
manufacturers such as Sumida, Panasonic, Coiltronics,
Coilcraft and Toko.
A plot of maximum duty cycle vs switching frequency is
shown in Figure 7.
2.0
Schottky Diode D1 Selection
The Schottky diode D1 shown in the front page schematic
conducts during the dead time between the conduction of
the power MOSFET switches. It is intended to prevent the
body diode of the synchronous MOSFET from turning on
1.5
DROPOUT
and storing charge during the dead time, which can cause
1.0
0.5
REGION
a modest (about 1%) ef?ciency loss. The diode can be
rated for about one half to one ?fth of the full load current
since it is on for only a fraction of the duty cycle. The peak
reverse voltage that the diode must withstand is equal to
the regulator output voltage. In order for the diode to be
effective, the inductance between it and the synchronous
0
0
0.25
0.50
0.75
1.0
MOSFET must be as small as possible, mandating that
V IN /V OUT
38145 F07
these components be placed adjacently. The diode can
Δ I L = 40% ?
V OUT = I O(MAX)
+
Figure 7. Maximum Switching Frequency vs Duty Cycle
Inductor Selection
An inductor should be chosen that can carry the maximum
input DC current which occurs at the minimum input volt-
age. The peak-to-peak ripple current is set by the inductance
and a good starting point is to choose a ripple current of
at least 40% of its maximum value:
I O(MAX)
1 ? D MAX
The required inductance can then be calculated to be:
be omitted if the ef?ciency loss is tolerable.
Output Capacitor Selection
In a boost converter, the output capacitor requirements
are demanding due to the fact that the current waveform
is pulsed. The choice of component(s) is driven by the
acceptable ripple voltage which is affected by the ESR,
ESL and bulk capacitance as shown in Figure 8e. The total
output ripple voltage is:
1 ESR
f ? C OUT 1– D MAX
where the ?rst term is due to the bulk capacitance and
second term due to the ESR.
L =
V IN(MIN) ? D MAX
f ? Δ I L
38145fc
15
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| LTC3814IFE-5#PBF | 功能描述:IC REG CTRLR BST PWM CM 16-TSSOP 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) |
| LTC3814IFE-5#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 16-TSSOP 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) |
| LTC3816EFE#PBF | 功能描述:IC DC-DC CTLR S-PHASE 38TSSOP 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) |
| LTC3816EFE#TRPBF | 功能描述:IC CONTROLLER S-PHASE 38TSSOP 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 |
| LTC3816EUHF#PBF | 功能描述:IC DC-DC CTLR S-PHASE 32QFN 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) |
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