参数资料
| 型号： | NCP1547DG |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/15页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 1.5A 8SOIC |
| 标准包装： | 98 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 1.5 V ~ 24 V |
| 输入电压： | 4.5 V ~ 40 V |
| PWM 型： | 混合物 |
| 频率 - 开关： | 340kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOICN |
NCP1547
oscillation, as shown in Figure 8. Similar to current mode
control, this oscillation occurs at the duty cycle greater than
50% and can be alleviated by using a larger inductor value.
The current limit threshold is reduced to Foldback Current
when the FB pin falls below Foldback Threshold. This
feature protects the IC and external components under the
power up or over ? load conditions.
30
25
20
15
10
5
0
0
0.5 1.0
1.5
SWITCHING CURRENT (A)
Figure 9. The Boost Pin Current Includes 7.0 mA
Pre ? Driver Current and Base Current when the
Switch is Turned On. The Beta Decline of the
Power Switch Further Increases the Base
Current at High Switching Current
Shutdown
The internal power switch will not turn on until the V IN
pin rises above the Startup Voltage. This ensures no
Figure 8. The Regulator in Current Limit
BOOST Pin
The BOOST pin provides base driving current for the
switching will occur until adequate supply voltage is
provided to the IC. Refer to Figure 10 for the SHDNB
(shutdown ? bar) pin input circuit.
power switch. A voltage higher than V IN provides required
headroom to turn on the power switch. This in turn reduces
IC power dissipation and improves overall system
efficiency. The BOOST pin can be connected to an external
boost ? strapping circuit which typically uses a 0.1 m F capacitor
and a 1N914 or 1N4148 diode, as shown in Figure 1.
When the power switch is turned on, the voltage on the
BOOST pin is equal to
SHDNB
20k
± 33%
1.2V
-
+
V IN
VBOOST + VIN ) VO * VF
where:
V F = diode forward voltage.
The anode of the diode can be connected to any DC
voltage as well as the regulated output voltage (Figure 1).
However, the maximum voltage on the BOOST pin shall not
exceed 40 V.
As shown in Figure 9, the BOOST pin current includes a
constant 7.0 mA pre ? driver current and base current
proportional to switch conducting current. A detailed
discussion of this current is conducted in Thermal
Consideration section. A 0.1 m F capacitor is usually
adequate for maintaining the Boost pin voltage during the on
V Z = 6V to 8V
GND
Figure 10.
The IC enters a sleep mode when the SHDNB pin is pulled
below the Shutdown Threshold Voltage. In sleep mode, the
power switch is kept open and the supply current reduces to
Shutdown Quiescent Current (1 m A typically). This pin has
an internal pull ? down current. When not in use, pull this pin
up to V CC with a resistor (See Figure 1). A 100 k W pullup
resistor will ensure safe operation from below 9 V and
during a 40 V load dump condition.
time.
http://onsemi.com
8
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| NCP1547DR2G | 功能描述:直流/直流开关调节器 340 KHZ REGULATOR 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 |
| NCP1547MNR2G | 功能描述:直流/直流开关调节器 340 KHZ 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 |
| NCP1550SN18T1 | 功能描述:直流/直流开关转换器 1.8V 2A Buck PWM/PFM RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| NCP1550SN18T1G | 功能描述:直流/直流开关转换器 1.8V 2A Buck PWM/PFM w/Enable Soft Start RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| NCP1550SN19T1 | 功能描述:直流/直流开关转换器 1.8V 2A Buck PWM/PFM RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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