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| 型号： | NCP5424DG |
| 厂商： | ON Semiconductor |
| 文件页数： | 7/18页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 16-SOIC |
| 产品变化通告： | Product Obsolescence 21/Jan/2010 |
| 标准包装： | 48 |
| PWM 型： | 电流/电压模式，V²? |
| 输出数： | 1 |
| 频率 - 最大： | 750kHz |
| 占空比： | 100% |
| 电源电压： | 10.8 V ~ 13.2 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
NCP5424
APPLICATIONS INFORMATION
THEORY OF OPERATION
The NCP5424 is a dual output or single two?phase power
supply controller that utilizes the V 2 control method. Two
synchronous V 2 buck regulators can be built using a single
controller or a single output converter that draws
programmable amounts of current from two input voltages.
The fixed?frequency architecture, driven from a common
oscillator, ensures a 180 ° phase differential between
channels.
V 2 Control Method
The V 2 method of control uses a ramp signal that is
generated by the ESR of the output capacitors. This ramp is
proportional to the AC current through the main inductor
and is offset by the DC output voltage. This control scheme
inherently compensates for variation in either line or load
conditions, since the ramp signal is generated from the
output voltage itself. The V 2 method differs from traditional
techniques such as voltage mode control, which generates an
artificial ramp, and current mode control, which generates
a ramp using the inductor current.
time to the output load step is not related to the crossover
frequency of the error signal loop.
The error signal loop can have a low crossover frequency,
since the transient response is handled by the ramp signal
loop. The main purpose of this ‘slow’ feedback loop is to
provide DC accuracy. Noise immunity is significantly
improved, since the error amplifier bandwidth can be rolled
off at a low frequency. Enhanced noise immunity improves
remote sensing of the output voltage, since the noise
associated with long feedback traces can be effectively
filtered.
Line and load regulation is drastically improved because
there are two independent control loops. A voltage mode
controller relies on the change in the error signal to
compensate for a deviation in either line or load voltage.
This change in the error signal causes the output voltage to
change corresponding to the gain of the error amplifier,
which is normally specified as line and load regulation. A
current mode controller maintains a fixed error signal during
line transients, since the slope of the ramp signal changes in
this case. However, regulation of load transients still requires
a change in the error signal. The V 2 method of control
RAMP
?
PWM
+
GATE(H)
GATE(L)
Output
Voltage
maintains a fixed error signal for both line and load variation,
since the ramp signal is affected by both line and load.
The stringent load transient requirements of modern
microprocessors require the output capacitors to have very
low ESR. The resulting shallow slope in the output ripple can
lead to pulse width jitter and variation caused by both random
and synchronous noise. A ramp waveform generated in the
Slope
Compensation
Error
Amplifier
?
V FB
oscillator is added to the ramp signal from the output voltage
to provide the proper voltage ramp at the beginning of each
switching cycle. This slope compensation increases the noise
COMP
Error
Signal
+
Reference
Voltage
immunity particularly at higher duty cycle (above 50%).
Start Up
Figure 3. V 2 Control with Slope Compensation
The V 2 control method is illustrated in Figure 3. The
output voltage generates both the error signal and the ramp
signal. Since the ramp signal is simply the output voltage, it
is affected by any change in the output, regardless of the
origin of that change. The ramp signal also contains the DC
portion of the output voltage, allowing the control circuit to
drive the main switch to 0% or 100% duty cycle as required.
A variation in line voltage changes the current ramp in the
inductor, which causes the V 2 control scheme to compensate
the duty cycle. Since any variation in inductor current modifies
the ramp signal, as in current mode control, the V 2 control
scheme offers the same advantages in line transient response.
A variation in load current will affect the output voltage,
modifying the ramp signal. A load step immediately changes
the state of the comparator output, which controls the main
switch. The comparator response time and the transition
speed of the main switch determine the load transient
response. Unlike traditional control methods, the reaction
The NCP5424 features a programmable Soft?Start
function, which is implemented through the Error Amplifier
and the external Compensation Capacitor. This feature
prevents stress to the power components and overshoot of
the output voltage during start?up. As power is applied to the
regulator, the NCP5424 Undervoltage Lockout circuit
(UVL) monitors the IC’s supply voltage (V CC ). The UVL
circuit resets an internal fault latch when the input voltage
exceeds 8.6 volts. This fault latch disables the error
amplifiers until it is reset. Once the amplifiers are enabled,
they start charging the compensation capacitors with a 30 uA
constant current that causes a linear voltage ramp. The
output of the error amplifier is connected internally to the
negative input of the PWM comparator. The comparator ’s
positive input is connected back to the feedback voltage pin
through a 0.45?volt offset. With the feedback voltage
starting at zero, the offset voltage forces the comparator
high, which prevents resetting the RS latches that control the
output drivers. Once the compensation capacitor voltage
reaches 0.45 volts, the PWM comparator will switch and
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相关代理商/技术参数 |
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| NCP5424DR2 | 功能描述:DC/DC 开关控制器 Dual Sync. Buck RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| NCP5424DR2G | 功能描述:DC/DC 开关控制器 Dual Sync. Buck w/Current Sharing RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| NCP5424EVB | 功能描述:电源管理IC开发工具 ANA SW REG 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 |
| NCP5425 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Dual Synchronous Buck Controller |
| NCP5425/D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Dual Synchronous Buck Controller |
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