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参数资料
| 型号： | IR3637STRPBF |
| 厂商： | International Rectifier |
| 文件页数： | 6/21页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 1 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 85% |
| 电源电压： | 4.5 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： | 0°C ~ 125°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 标准包装 |
| 配用： | IRPP3637-12A-ND - KIT REF DES 12A 1PH SYNC BUCK IRDC3637-ND - BOARD EVAL SYNC BUCK REGULATOR |
| 其它名称： | IR3637STRPBFDKR |
IR3637SPBF
APPLICATION INFORMATION
Css ? 25 × t START ( μ F)
---(2)
Design Example:
The following example is a typical application for IR3637.
Appliaction circuit is shown in page 12.
V IN = Vcc = 5V
Vc=12V
V OUT = 1.8V
I OUT = 6A
? V OUT = 50mV
F S = 400kHz
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
0.8V. The divider is ratioed to provide 0.8V at the Fb pin
when the output is at its desired value. The output volt-
age is defined by using the following equation:
Where t START is the desired start-up time (ms)
For a start-up time of 4ms, the soft-start capacitor will
be 0.1 μ F. Choose a ceramic capacitor at 0.1 μ F.
Boost Supply for Single 5V appliaction
To drive the high side switch, it is necessary to supply a
gate voltage at least 4V grater than the bus voltage. This
is achieved by using a charge pump configuration as
shown in Figure 6. This method is simple and inexpen-
sive. The operation of the circuit is as follows: when the
lower MOSFET is turned on, the capacitor (C1) is pulled
down to ground and charges, up to V BUS value, through
the diode (D1). The bus voltage will be added to this
voltage when upper MOSFET turns on in next cycle,
and providing supply voltage (Vc) through diode (D2). Vc
is approximately:
( R R )
1+
V OUT = V REF ×
6
5
---(1)
Vc ? 2V BUS - (V D1 + V D2 )
Capacitors in the range of 0.1 μ F and 1 μ F are generally
When an external resistor divider is connected to the
output as shown in Figure 5.
adequate for most applications. The diode must be a
fast recovery device to minimize the amount of charge
IR3637
Fb
V OUT
R 6
R 5
fed back from the charge pump capacitor into V BUS . The
diodes need to be able to block the full power rail volt-
age, which is seen when the high side MOSFET is
switched on. For low voltage application, schottky di-
odes can be used to minimize forward drop across the
diodes at start up.
V BUS
D1
Figure 5 - Typical application of the IR3637 for pro-
gramming the output voltage.
C3
Vc
D2
V BUS
Equation (1) can be rewritten as:
C2
C1
Q1
(
R 6 = R 5 ×
)
V OUT
V REF
Choose R 5 = 1K ?
-1
IR3637
HDrv
Q2
L
This will result to R 6 = 1.25K ?
If the high value feedback resistors are used, the input
bias current of the Fb pin could cause a slight increase
in output voltage. The output voltage set point can be
more accurate by using precision resistor.
Soft-Start Programming
The soft-start timing can be programmed by selecting
the soft-start capacitance value. The start-up time of the
converter can be calculated by using:
Figure 6 - Charge pump circuit.
Input Capacitor Selection
The input filter capacitor should be based on how much
ripple the supply can tolerate on the DC input line. The
ripple current generated during the on time of upper
MOSFET should be provided by input capacitor. The RMS
value of this ripple is expressed by:
6
www.irf.com
Rev.1.1
06/16/05
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| IR3638 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:High Frequency Synchronous |
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| IR3638STRPBF | 功能描述:电压模式 PWM 控制器 HI FREQ SYNC PWM 400kHz 0.6V Track RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| IR3640MPBF | 功能描述:IC REG CTRLR BUCK PWM VM 20-MLPQ 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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
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