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参数资料
| 型号： | NCP1546DG |
| 厂商： | ON SEMICONDUCTOR |
| 元件分类： | 稳压器 |
| 英文描述： | 1.5A 170 kHz Low Voltage Buck Regulator |
| 中文描述： | SWITCHING REGULATOR, PDSO8 |
| 封装： | LEAD FREE, SOIC-8 |
| 文件页数： | 13/15页 |
| 文件大小： | 212K |
| 代理商： | NCP1546DG |
NCP1546
http://onsemi.com
7
Figure 4. Oscillator Frequency Versus Junction
Temperature
0
20
100
TJ, JUNCTION TEMPERATURE (°C)
f OS
C
,FREQUENCY
(%)
90
92.5
95
97.5
100
102.5
40
60
80
140
120
An external clock signal can sync the NCP1546 to a higher
frequency. The SYNC pin equivalent input circuit is shown
in Figure 5.
Figure 5.
Sync
GND
50k
±33%
VZ = 11V
to 20V
10k
±33%
50k
±33%
The rising edge of the sync pulse turns on the power
switch to start a new switching cycle, as shown in Figure 6.
There is approximately 0.5
ms delay between the rising edge
of the sync pulse and rising edge of the VSW pin voltage. The
sync threshold is TTL logic compatible, and duty cycle of
the sync pulses can vary from 10% to 90%. The frequency
foldback feature is disabled during the sync mode.
Figure 6. A NCP1546 Buck Regulator is Synchronized
to an External 350 kHz Pulse Signal
Power Switch and Current Limit
The collector of the builtin NPN power switch is
connected to the VIN pin, and the emitter to the VSW pin.
When the switch turns on, the VSW voltage is equal to the
VIN minus switch Saturation Voltage. In the buck regulator,
the VSW voltage swings to one diode drop below ground
when the power switch turns off, and the inductor current is
commutated to the catch diode. Due to the presence of high
pulsed current, the traces connecting the VSW pin, inductor
and diode should be kept as short as possible to minimize the
noise and radiation. For the same reason, the input capacitor
should be placed close to the VIN pin and the anode of the
diode.
The saturation voltage of the power switch is dependent
on the switching current, as shown in Figure 7.
Figure 7. The Saturation Voltage of the Power Switch
Increases with the Conducting Current
0
0.5
1.0
1.5
SWITCHING CURRENT (A)
V
IN
V
SW
(V)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
The NCP1546 contains pulsebypulse current limiting
to protect the power switch and external components. When
the peak of the switching current reaches the Current Limit,
the power switch turns off after the Current Limit Delay. The
switch will not turn on until the next switching cycle. The
current limit threshold is independent of switching duty
cycle. The maximum load current, given by the following
formula under continuous conduction mode, is less than the
Current Limit due to the ripple current.
IO(MAX) + ILIM *
VO(VIN * VO)
2(L)(VIN)(fs)
where:
fS = switching frequency,
ILIM = current limit threshold,
VO = output voltage,
VIN = input voltage,
L = inductor value.
When the regulator runs under current limit, the
subharmonic oscillation may cause low frequency
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 overload conditions.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCP1546DR2G | 功能描述:直流/直流开关调节器 1.5A LOW VOLTAGE REG 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 |
| NCP1546MNR2G | 功能描述:直流/直流开关调节器 170 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 |
| NCP1547DG | 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 |
| 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 |
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