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参数资料
| 型号： | NCP1216AFORWGEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/18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
Dynamic Self ? Supply
The DSS principle is based on the charge/discharge of the
V CC bulk capacitor from a low level up to a higher level. We
can easily describe the current source operation with a bunch
of simple logical equations:
POWER ? ON: If V CC < VCC OFF then the Current Source
is ON, no output pulses
If V CC decreasing > VCC ON then the Current Source is
OFF, output is pulsing
If V CC increasing < VCC OFF then the Current Source is
ON, output is pulsing
Typical values are: VCC OFF = 12.2 V, VCC ON = 10 V
To better understand the operational principle, Figure 18
Application note AND8069/D details tricks to widen the
NCP1216 driving implementation, in particular for large Q g
MOSFETs. This document can be downloaded at
www.onsemi.com/pub/Collateral/AND8069 ? D.PDF.
Ramp Compensation
Ramp compensation is a known mean to cure
sub ? harmonic oscillations. These oscillations take place at
half the switching frequency and occur only during
Continuous Conduction Mode (CCM) with a duty ? cycle
greater than 50%. To lower the current loop gain, one usually
injects between 50% and 100% of the inductor down ? slope.
Figure 19 depicts how internally the ramp is generated:
offers the necessary light:
V ripple = 2.2 V
VCC OFF = 12.2 V
VCC ON = 10 V
DC max = 75 ° C
2.9V
0V
ON, I = 8 mA
OFF, I = 0 mA
L.E.B
19 k
CS
R comp
R sense
Itotal [ Fsw Qg ) ICC1.
Itotal Vpin8.
65 kHz + 251 mV m s ramp.
2.9
0.75
Vout ) Vf Np
+ 371 mA m s or37 mV m s
19 k divratio
+ 2.37 k W
Output Pulse
10 30 50 70 90
Figure 18. The Charge/Discharge Cycle Over a
10 m F V CC Capacitor
The DSS behavior actually depends on the internal IC
consumption and the MOSFET’s gate charge Q g . If we
select a 600 V 10 A MOSFET featuring a 30 nC Q g , then we
can compute the resulting average consumption supported
by the DSS which is:
(eq. 1)
The total IC heat dissipation incurred by the DSS only is
given by:
(eq. 2)
Suppose that we select the NCP1216P065 with the above
MOSFET, the total current is
(30 n 65 k) ) 900 m + 2.9 mA. (eq. 3)
Supplied from a 350 VDC rail (250 VAC), the heat
dissipated by the circuit would then be:
350 V 2.9 mA + 1 W (eq. 4)
As you can see, it exists a tradeoff where the dissipation
capability of the NCP1216 fixes the maximum Q g that the
circuit can drive, keeping its dissipation below a given
target. Please see the “Power Dissipation” section for a
complete design example and discover how a resistor can
help to heal the NCP1216 heat equation.
From Set ? point
Figure 19. Inserting a Resistor in Series with the
Current Sense Information brings Ramp
Compensation
In the NCP1216, the ramp features a swing of 2.9 V with
a Duty cycle max at 75%. Over a 65 kHz frequency, it
corresponds to a
(eq. 5)
In our FLYBACK design, let’s suppose that our primary
inductance L p is 350 m H, delivering 12 V with a Np : Ns
ratio of 1:0.1. The OFF time primary current slope is thus
given by:
(eq. 6)
Lp Ns
when projected over an R sense of 0.1 W , for instance. If we
select 75% of the down ? slope as the required amount of
ramp compensation, then we shall inject 27 mV/ m s. Our
internal compensation being of 251 mV/ m s, the divider ratio
(divratio) between R comp and the 19 k W is 0.107. A few lines
of algebra to determine R comp :
(eq. 7)
1 * divratio
Frequency Jittering
Frequency jittering is a method used to soften the EMI
signature by spreading the energy in the vicinity of the main
switching component. NCP1216 offers a $ 4% deviation of
http://onsemi.com
10
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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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