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| 型号： | IR3856MTRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 19/35页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 6A 17PQFN |
| 产品培训模块： | SupIRBuck? Family and POL Design Tools Overview |
| 标准包装： | 4,000 |
| 系列： | SupIRBuck™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.7 V ~ 18.9 V |
| 输入电压： | 1.5 V ~ 21 V |
| PWM 型： | 电压模式 |
| 频率 - 开关： | 225kHz ~ 1.65MHz |
| 电流 - 输出： | 6A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 17-PowerVQFN |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 17-PQFN（4x5） |
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PD-97528
IR3856MPbF
R 9 = R 8 ? ? ?
? ? .......... .......... .......... .... (9)
Application Information
Design Example:
The following example is a typical application for
IR3856. The application circuit is shown on page
25.
V in = 12 V ( 13.2V max)
V o = 1.8 V
I o = 6 A
Δ V o ≤ ± 5% of V o
F s = 600 kHz
Enabling the IR3856
As explained earlier, the precise threshold of the
Enable lends itself well to implementation of a
UVLO for the Bus Voltage.
V in
When an external resistor divider is connected to
the output as shown in figure 12.
Equation (6) can be rewritten as:
? V ref ?
? V o ? V ref ?
For the calculated values of R8 and R9 see
feedback compensation section.
V OU T
IR3856
IR3624
R 8
Fb
R 9
Fig. 12. Typical application of the IR3856 for
programming the output voltage
Soft-Start Programming
The soft-start timing can be programmed by
IR3856
Enable
R 1
R 2
selecting the soft-start capacitance value. From
(1), for a desired start-up time of the converter,
the soft start capacitor can be calculated by
using:
C SS ( μ F ) = T start ( ms ) × 0.02857 .......... (10)
= V EN = 1.36V..... ...... (6)
R 2
R 1 + R 2
R 2 = R 1
V EN
For a maximum Enable threshold of V EN = 1.36 V
V in (min) *
.......... (7)
V in( min ) ? V EN
For a V in (min) =10.2V, R 1 =49.9K and R 2 =7.5K is a
good choice.
Programming the frequency
For F s = 600 kHz, select R t = 23.7 k ? , using
Table. 1.
Output Voltage Programming
Output voltage is programmed by reference
voltage and external voltage divider. The Fb pin
is the inverting input of the error amplifier, which
is internally referenced to 0.7V. The divider is
ratioed to provide 0.7V at the Fb pin when the
output is at its desired value. The output voltage
is defined by using the following equation:
Where T start is the desired start-up time (ms).
For a start-up time of 3.5ms, the soft-start
capacitor will be 0.099 μ F. Choose a 0.1 μ F
ceramic capacitor.
Bootstrap Capacitor Selection
To drive the Control FET, it is necessary to
supply a gate voltage at least 4V greater than
the 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), as shown in
Fig. 13. 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 .......... .......... ...... (11)
When the upper MOSFET turns on in the next
V o = V ref ? ? ? 1 +
R 8 ?
R 9 ? ?
Rev 4.0
?
?
? .......... .......... .(8)
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 Vc
19
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相关代理商/技术参数 |
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|---|---|
| IR3856WMPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGHLY EFFICIENT INTEGRATED 6A, SYNCHRONOUS BUCK REGULATOR |
| IR3856WMTR1PBF | 功能描述:直流/直流开关调节器 6A SupIRBuck Reg 750kHz, 1.5-16V in RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| IR3856WMTRPBF | 功能描述:直流/直流开关调节器 6A SupIRBuck Reg 750kHz, 1.5-16V in RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| IR3859MPBF | 制造商:IRF 制造商全称:International Rectifier 功能描述:HIGHLY EFFICIENT INTEGRATED 9A, SYNCHRONOUS BUCK REGULATOR |
| IR3859MTR1PBF | 功能描述:直流/直流开关调节器 9A SupIRBuck Reg 250-1500kHz, 1.5-21V RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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