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参数资料
| 型号： | NCV8842MNR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 6/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 1.5A 18DFN |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出数： | 1 |
| 输入电压： | 4.5 V ~ 40 V |
| PWM 型： | 混合物 |
| 频率 - 开关： | 170kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 150°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 18-VFDFN 裸露焊盘 |
| 包装： | 剪切带 (CT) |
| 供应商设备封装： | 18-DFN（5x6） |
| 其它名称： | NCV8842MNR2GOSCT |
NCV8842
APPLICATIONS INFORMATION
THEORY OF OPERATION
V 2 Control
The NCV8842 buck regulator provides a high level of
integration and high operating frequencies allowing the
layout of a switch ? mode power supply in a very small board
area. This device is based on the proprietary V 2 control
architecture. V 2 control uses the output voltage and its ripple
as the ramp signal, providing an ease of use not generally
associated with voltage or current mode control. Improved
line regulation, load regulation and very fast transient
response are also major advantages.
current of the inductor L1 and the ESR (equivalent series
resistor) of the output capacitor C1.
The slope compensation signal is a fixed voltage ramp
provided by the oscillator. Adding this signal eliminates
subharmonic oscillation associated with the operation at
duty cycle greater than 50%. The artificial ramp also ensures
the proper PWM function when the output ripple voltage is
inadequate. The slope compensation signal is properly sized
to serve it purposes without sacrificing the transient
response speed.
Under load and line transient, not only the ramp signal
changes, but more significantly the DC component of the
feedback voltage varies proportionally to the output voltage.
V IN
Duty Cycle
S1
D1
L1
C1
R1
V O
FFB path connects both signals directly to the PWM
comparator. This allows instant modulation of the duty cycle
to counteract any output voltage deviations. The transient
response time is independent of the error amplifier
Buck
Controller
bandwidth. This eliminates the delay associated with error
amplifier and greatly improves the transient response time.
The error amplifier is used here to ensure excellent DC
Latch S
V 2
Control
Oscillator
R
PWM Com-
parator
Slope
Comp
FFB
SFB
V C
Error
Amplifier
+
?
V REF
V FB
R2
accuracy.
Error Amplifier
The NCV8842 has a transconductance error amplifier,
whose non ? inverting input is connected to an Internal
Reference Voltage generated from the on ? chip regulator.
The inverting input connects to the V FB pin. The output of
the error amplifier is made available at the V C pin. A typical
frequency compensation requires only a 0.1 m F capacitor
connected between the V C pin and ground, as shown in
Figure 1. This capacitor and error amplifier ’s output
resistance (approximately 8.0 M W ) create a low frequency
pole to limit the bandwidth. Since V 2 control does not
Figure 3. Buck Converter with V 2 Control.
As shown in Figure 3, there are two voltage feedback
paths in V 2 control, namely FFB(Fast Feedback) and
SFB(Slow Feedback). In FFB path, the feedback voltage
connects directly to the PWM comparator. This feedback
path carries the ramp signal as well as the output DC voltage.
Artificial ramp derived from the oscillator is added to the
feedback signal to improve stability. The other feedback
path, SFB, connects the feedback voltage to the error
amplifier whose output V C feeds to the other input of the
PWM comparator. In a constant frequency mode, the
oscillator signal sets the output latch and turns on the switch
S1. This starts a new switch cycle. The ramp signal,
composed of both artificial ramp and output ripple,
eventually comes across the V C voltage, and consequently
resets the latch to turn off the switch. The switch S1 will turn
on again at the beginning of the next switch cycle. In a buck
converter, the output ripple is determined by the ripple
require a high bandwidth error amplifier, the frequency
compensation is greatly simplified.
The V C pin is clamped below Output High Voltage. This
allows the regulator to recover quickly from over current or
short circuit conditions.
Oscillator and Sync Feature
The on ? chip oscillator is trimmed at the factory and
requires no external components for frequency control. The
high switching frequency allows smaller external
components to be used, resulting in a board area and cost
savings. The tight frequency tolerance simplifies magnetic
components selection. The switching frequency is reduced
to no more than 25% of the nominal value when the V FB pin
voltage is below Frequency Foldback Threshold. In short
circuit or over ? load conditions, this reduces the power
dissipation of the IC and external components.
The oscillator frequency varies with junction
temperature, as seen in the following graph.
http://onsemi.com
6
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCV8842MNR2GEVB | 功能描述:BOARD EVAL FOR NCV8842 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| NCV8842PWG | 功能描述:直流/直流开关转换器 1.5A LO VLT BUCK REG 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 |
| NCV8842PWGEVB | 功能描述:电源管理IC开发工具 NCV8842 EVAL BRD RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| NCV8842PWR2G | 功能描述:直流/直流开关转换器 1.5A LO VLT BUCK REG 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 |
| NCV8843 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:1.5 A, 340 kHz, Buck Regulator with Synchronization Capability |
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