参数资料
型号: IRDC3837
厂商: International Rectifier
文件页数: 22/36页
文件大小: 0K
描述: KIT EVAL REG 14A SUPIRBUCK DC/DC
标准包装: 1
系列: SupIRBuck™
主要目的: DC/DC,LDO 步降
输出及类型: 1,非隔离
输出电压: 1.8V
电流 - 输出: 14A
输入电压: 12V
稳压器拓扑结构: 降压
频率 - 开关: 600kHz
板类型: 完全填充
已供物品:
已用 IC / 零件: IR3837
IR3837MPbF
Inductor Selection
The inductor is selected based on output power,
operating frequency and efficiency requirements.
A low inductor value causes large ripple current,
resulting in the smaller size, faster response to a
load transient but poor efficiency and high output
noise. Generally, the selection of the inductor
value can be reduced to the desired maximum
ripple current in the inductor ( ? 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 ?
; ? t ? D ?
L ? ? V in ? V o ? ?
Fig. 17. Bootstrap circuit to generate
Vc voltage
A bootstrap capacitor of value 0.1uF is suitable
? i
? t
V o
V in ? ? i * F s
1
F s
.......... .......... .......... . (14)
for most applications.
Input Capacitor Selection
The ripple current generated during the on time of
the control FET should be provided by the input
capacitor. The RMS value of this ripple is
expressed by:
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
V o
? V o ( ESL ) ? ? in
? V ? V o ?
I RMS ? I o ? D ? ( 1 ? D ) .......... .......... ....(12)
D ? .......... .......... .......... .. (13)
V in
Where:
D is the Duty Cycle
I RMS is the RMS value of the input capacitor
current.
Io is the output current.
For I o =14A and D = 0.15, the I RMS = 5.0A.
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 4x10uF, 16V ceramic
capacitors, ECJ-3YX1C106K from Panasonic. In
addition to these, although not mandatory, a
1x330uF, 25V SMD capacitor EEV-FK1E331P
may also be used as a bulk capacitor and is
recommended if the input power supply is not
If Δ i ≈ 35%( I o ), then the output inductor is
calculated to be 0.52 μ H. Select L =0.51 μ H,
59PR9876N, from VITEC which provides a
compact, low profile inductor suitable for this
application.
Output Capacitor Selection
The voltage ripple and transient requirements
determine the output capacitors type and values.
The criteria is normally based on the value of the
Effective Series Resistance (ESR). However the
actual capacitance value and the Equivalent
Series Inductance (ESL) are other contributing
components. These components can be
described as
? V o ? ? V o ( ESR ) ? ? V o ( ESL ) ? ? V o ( C )
? V o ( ESR ) ? ? I L * ESR
? * ESL
? L ?
located close to the converter.
Rev 1.31
? V o ( C ) ?
? I L
8 * C o * F s
.......... .......... ..... (15)
22
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