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參數(shù)資料
| 型號： | NCP1508 |
| 廠商： | ON SEMICONDUCTOR |
| 英文描述： | Up to 500 mA, 1 MHz, High Efficiency Synchronous Step−Down DC−DC Converter in DFN Package |
| 文件頁數(shù)： | 11/15頁 |
| 文件大小： | 414K |
| 代理商： | NCP1508 |
NCP1508
http://onsemi.com
11
Table 1. Operating Mode Selection
SYNC Pin State
Operating Mode
LOW
Pulsed Mode (PM)
HIGH
PWM, 1 MHz Switch Frequency
CLOCK
PWM, Frequency Synchronization
Output Voltage Selection
The output voltage is digitally programmed to one of
four voltage levels depending on the logic state of CB0 and
CB1. Therefore if the NCP1508’s load, such as a digital
cellular phone’s baseband processor, supports dynamic
power management, the device can lower or raise its core
voltage under software control. When combined with the
pulsed current mode function in low load situations, this
active voltage management further stretches the useful
operating life of the handset between charges. Figure 24
shows a typical transition between 1.5 to 1.89 volts.
The output voltage levels are listed in Table 2. The CB0
has a pull down resistor and the CB1 has a pullup resistor.
The default output voltage is 1.3 V when CB0 and CB1 are
floating.
Table 2. Truth Table for CB0 and CB1 with the
corresponding output voltage
CB0
CB1
Vout(V)
0
0
1.0
0
1
1.3
1
1
1.5
1
0
1.89
Soft
Start
The NCP1508 uses soft
start to limit the inrush current
when the device is initially powered up or enabled.
Soft
start is implemented by gradually increasing the
reference voltage until it reaches the full reference voltage.
During startup, a pulsed current source charges the internal
soft
start capacitor to provide gradually increasing
reference voltage for the PWM loop. When the voltage
across the capacitor ramps up to the nominal reference
voltage, the pulsed current source will be switched off and
the reference voltage will switch to the regular reference
voltage. From Figure 21, it show the soft
start time is about
1.5 ms.
Shutdown Mode
When the SHD pin has a voltage applied of less than
0.4 V, the NCP1508 will be disabled. In shutdown mode,
the internal reference, oscillator and most of the control
circuitries are turned off. Therefore, the typical current
consumption will be 0.1 A (typical value).
Applying a voltage above 1.2 V to SHD pin will enable
the device for normal operation. The device will go through
soft
start to normal operation.
Thermal Shutdown
Internal Thermal Shutdown circuitry is provided to
protect the integrated circuit in the event that the maximum
junction temperature is exceeded. If the junction
temperature exceeds 160
°
C, the device shuts down. In this
mode switch Q1 and Q2 and the control circuits are all
turned off. The device restarts in soft
start after the
temperature drops below 135 C. This feature is provided
to prevent catastrophic failures from accidental device
overheating and it is not intended as a substitute for proper
heatsinking.
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| NCP1508MNR2 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 High Efficiency Buck RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| NCP1508MNR2G | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 High Efficiency Buck Synchronous DC/DC RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| NCP1509MNR2 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 High Efficiency Buck RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| NCP1509MNR2G | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 High Efficiency Buck Synchronous DC/DC RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| NCP1510AFCT1 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 High Efficiency Buck RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
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