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| 型号： | NCP1216AFORWGEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 13/18页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL NCP1216A 35W |
| 设计资源： | NCP1216AFORWGEVB Schematic NCP1216AFORWGEVB Gerber Files NCP1216AFORWGEVB Bill of Materials |
| 标准包装： | 1 |
| 系列： | * |
NCP1216, NCP1216A
3. Implement Figure 3, from AN8069/D, Solution: This is
another possible option to keep the DSS functionality (good
short ? circuit protection and EMI jittering) while driving any
types of MOSFETs. This solution is recommended when the
designer plans to use SOIC ? 8 controllers.
4. Connect an Auxiliary Winding: If the mains conditions
are such that you simply can’t match the maximum power
dissipation, then you need to connect an auxiliary winding
to permanently disconnect the startup source.
Overload Operation
In applications where the output current is purposely not
controlled (e.g. wall adapters delivering raw DC level), it is
interesting to implement a true short ? circuit protection. A
short ? circuit actually forces the output voltage to be at a low
level, preventing a bias current to circulate in the
Optocoupler LED. As a result, the FB pin level is pulled up
to 4.2 V, as internally imposed by the IC. The peak current
setpoint goes to the maximum and the supply delivers a
rather high power with all the associated effects. Please note
that this can also happen in case of feedback loss, e.g. a
broken Optocoupler. To account for this situation, NCP1216
hosts a dedicated overload detection circuitry. Once
activated, this circuitry imposes to deliver pulses in a burst
manner with a low duty ? cycle. The system auto ? recovers
when the fault condition disappears.
During the startup phase, the peak current is pushed to the
maximum until the output voltage reaches its target and the
feedback loop takes over. This period of time depends on
normal output load conditions and the maximum peak
current allowed by the system. The time ? out used by this IC
works with the V CC decoupling capacitor: as soon as the
V CC decreases from the VCC OFF level (typically 12.2 V) the
device internally watches for an overload current situation.
If this condition is still present when the VCC ON level is
reached, the controller stops the driving pulses, prevents the
self ? supply current source to restart and puts all the circuitry
in standby, consuming as little as 350 m A typical (I CC3
parameter). As a result, the V CC level slowly discharges
toward 0 V. When this level crosses 5.6 V typical, the
controller enters a new startup phase by turning the current
source on: V CC rises toward 12.2 V and again delivers
output pulses at the VCC OFF crossing point. If the fault
condition has been removed before VCC ON approaches,
then the IC continues its normal operation. Otherwise, a new
fault cycle takes place. Figure 25 shows the evolution of the
signals in presence of a fault.
V CC
12.2 V
Regulation
Occurs Here
Latchoff
10 V
Phase
5.6 V
Time
Drv
Driver
Driver
VCC OFF = 12.2 V
VCC ON = 10 V
VCC latch = 5.6 V
Internal
Pulses
Pulses
Time
Fault Flag
Fault is
Relaxed
Time
Startup Phase
Fault Occurs Here
Figure 25.
If the fault is relaxed during the V CC natural fall down
sequence, the IC automatically resumes.
If the fault still persists when V CC reached VCC ON , then the
controller cuts everything off until recovery.
Calculating the VCC Capacitor
As the above section describes, the fall down sequence
depends upon the V CC level: how long does it take for the
V CC line to go from 12.2 V to 10 V . The required time
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| NCP1216AP100 | 功能描述:开关变换器、稳压器与控制器 Current Mode PWM RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| NCP1216AP100G | 功能描述:电流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1216AP133 | 功能描述:电流型 PWM 控制器 Current Mode PWM RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1216AP133G | 功能描述:电流型 PWM 控制器 Current Mode PWM w/50% Duty Cycle Max RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| NCP1216AP65 | 功能描述:电流型 PWM 控制器 Current Mode PWM RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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