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参数资料
| 型号： | IRDC3831 |
| 厂商： | International Rectifier |
| 文件页数： | 17/31页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL SYNC BUCK CONVERTER |
| 产品变化通告： | (EP) Parts Discontinuation 25/May/2012 |
| 标准包装： | 1 |
| 系列： | SupIRBuck™ |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 0.75V |
| 电流 - 输出： | 8A |
| 输入电压： | 12V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 400kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | IR3831 |
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IR3831MPbF
Bootstrap Capacitor Selection
To drive the Control FET, it is necessary to
supply a gate voltage at least 4V greater than the
D =
V o
V in
.......... .......... .......... .. (13)
voltage at the SW pin, which is connected the
source of the Control FET . This is achieved by
using a bootstrap configuration, which comprises
the internal bootstrap diode and an external
bootstrap capacitor (C6). The operation of the
circuit is as follows: When the lower MOSFET is
turned on, the capacitor node connected to SW is
pulled down to ground. The capacitor charges
towards V cc through the internal bootstrap diode,
which has a forward voltage drop V D . The voltage
V c across the bootstrap capacitor C6 is
approximately given as
V c ? V cc ? V D .......... .......... .......... .......... (10)
When the upper MOSFET turns on in the next
cycle, the capacitor node connected to SW rises
to the bus voltage V in . However, if the value of C6
is appropriately chosen, the voltage V c across C6
remains approximately unchanged and the
voltage at the Boot pin becomes
V Boot ? V in + V cc ? V D .......... .......... .......... .......... (11)
Where:
D is the Duty Cycle
I RMS is the RMS value of the input capacitor
current.
I o is the output current.
For I o =8 A and D = 0.0625, the I RMS = 1.94 A
Ceramic capacitors are recommended due to
their peak current capabilities. They also feature
low ESR and ESL at higher frequency which
enables better efficiency. For this application, it is
advisable to have 3x10uF 16V ceramic capacitors
ECJ-3YX1C106K from Panasonic. In addition to
these, although not mandatory, a 330uF 25V
SMD capacitor EEV-FK1E331P from Panasonic
may be used as a bulk capacitor, and is
recommended if the input power supply is not
located close to the converter.
Inductor Selection
The inductor is selected based on output power,
operating frequency and efficiency requirements.
A low inductor value results in a smaller size and
faster response to a load transient but poor
efficiency and high output noise due to large
ripple current. Generally, the selection of the
inductor value can be reduced to the desired
maximum ripple current in the inductor ( Δ i ) . The
optimum point is usually found between 20% and
50% ripple of the output current.
For the buck converter, the inductor value for the
desired operating ripple current can be
determined using the following relation:
V in ? V o = L ?
; Δ t = D ?
Fig. 11. Bootstrap circuit to generate
Vc voltage
Δ i
Δ t
L = ( V in ? V o ) ?
1
F s
V o
V in ? Δ i * F s
.......... .......... ... (14)
A bootstrap capacitor of value 0.1uF is suitable
for most applications.
Input Capacitor Selection
The ripple current generated during the on time of
the upper MOSFET should be provided by the
input capacitor. The RMS value of this ripple is
expressed by:
I RMS = I o ? D ? ( 1 ? D ) .......... .......... ....(12)
11/05/10
Where: V in = Maximum input voltage
V o = Output Voltage
Δ i = Inductor ripple current
F s = Switching frequency
Δ t = Turn on time
D = Duty cycle
If Δ i ≈ 35%( I o ), then the output inductor is
calculated to be 0.63 μ H. Select L =0.6 μ H.
The MPL104-0R6 from Delta provides a compact,
low profile inductor suitable for this application.
17
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相关代理商/技术参数 |
参数描述 |
|---|---|
| IRDC3831W | 功能描述:电源管理IC开发工具 User Guide IR3831W Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3832W | 功能描述:电源管理IC开发工具 User Guide IR3832W Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3837 | 功能描述:电源管理IC开发工具 User Guide IR3837 Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| IRDC3837 | 制造商:International Rectifier 功能描述:; MCU Supported Families:IR3837; Feature |
| IRDC3838 | 功能描述:电源管理IC开发工具 User Guide IR3838 Eval Brd RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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