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| 型号： | NCV5171EDR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 10/19页 |
| 文件大小： | 0K |
| 描述： | IC REG MULTI CONFIG 1.5A 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 升压（升压），反相，回扫，正向转换器，Sepic |
| 输出数： | 1 |
| 输入电压： | 2.7 V ~ 30 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 280kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOICN |
NCV5171, NCV5173
Switch Driver and Power Switch
The switch driver receives a control signal from the logic
section to drive the output power switch. The switch is
grounded through emitter resistors (63 m W total) to the
PGND pin. PGND is not connected to the IC substrate so that
switching noise can be isolated from the analog ground. The
peak switching current is clamped by an internal circuit. The
clamp current is guaranteed to be greater than 1.5 A and
varies with duty cycle due to slope compensation. The
power switch can withstand a maximum voltage of 40 V on
the collector (V SW pin). The saturation voltage of the switch
is typically less than 1 V to minimize power dissipation.
Short Circuit Condition
When a short circuit condition happens in a boost circuit,
the inductor current will increase during the whole
switching cycle, causing excessive current to be drawn from
the input power supply. Since control ICs don’t have the
means to limit load current, an external current limit circuit
(such as a fuse or relay) has to be implemented to protect the
load, power supply and ICs.
In other topologies, the frequency shift built into the IC
prevents damage to the chip and external components. This
feature reduces the minimum duty cycle and allows the
transformer secondary to absorb excess energy before the
switch turns back on.
I L
V OUT
on. This is a part of the NCV5171/73’s normal operation.
The turn ? on of the power switch accounts for the initial
current swing.
When the V C pin voltage rises above the threshold, the
internal power switch starts to switch and a voltage pulse can
be seen at the V SW pin. Detecting a low output voltage at the
FB pin, the built ? in frequency shift feature reduces the
switching frequency to a fraction of its nominal value,
reducing the minimum duty cycle, which is otherwise
limited by the minimum on ? time of the switch. The peak
current during this phase is clamped by the internal current
limit.
When the FB pin voltage rises above 0.4 V, the frequency
increases to its nominal value, and the peak current begins
to decrease as the output approaches the regulation voltage.
The overshoot of the output voltage is prevented by the
active pull ? on, by which the sink current of the error
amplifier is increased once an overvoltage condition is
detected. The overvoltage condition is defined as when the
FB pin voltage is 50 mV greater than the reference voltage.
COMPONENT SELECTION
Frequency Compensation
The goal of frequency compensation is to achieve
desirable transient response and DC regulation while
ensuring the stability of the system. A typical compensation
network, as shown in Figure 26, provides a frequency
response of two poles and one zero. This frequency response
is further illustrated in the Bode plot shown in Figure 27.
V C
R1
V CC
V C
NCV5171/73
C1
C2
GND
Figure 26. A Typical Compensation Network
fP1 +
Figure 25. Startup Waveforms of Circuit Shown in
the Application Diagram. Load = 400 mA.
The NCV5171/73 can be activated by either connecting
the V CC pin to a voltage source or by enabling the SS pin.
Startup waveforms shown in Figure 25 are measured in the
boost converter demonstrated in the Application Diagram
on the page 2 of this document. Recorded after the input
voltage is turned on, this waveform shows the various
phases during the power up transition.
When the V CC voltage is below the minimum supply
voltage, the V SW pin is in high impedance. Therefore,
current conducts directly from the input power source to the
output through the inductor and diode. Once V CC reaches
approximately 1.5 V, the internal power switch briefly turns
The high DC gain in Figure 27 is desirable for achieving
DC accuracy over line and load variations. The DC gain of
a transconductance error amplifier can be calculated as
follows:
GainDC + GM RO
where:
G M = error amplifier transconductance;
R O = error amplifier output resistance ? 1 M W .
The low frequency pole, f P1, is determined by the error
amplifier output resistance and C1 as:
1
2 p C1R O
http://onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCV5173EDR2G | 功能描述:直流/直流开关转换器 1.5A 560KHZ BOOST RG 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 |
| NCV5230DR2G | 功能描述:运算放大器 - 运放 LOW VOLTAGE OP-AMP RoHS:否 制造商:STMicroelectronics 通道数量:4 共模抑制比（最小值）:63 dB 输入补偿电压:1 mV 输入偏流（最大值）:10 pA 工作电源电压:2.7 V to 5.5 V 安装风格:SMD/SMT 封装 / 箱体:QFN-16 转换速度:0.89 V/us 关闭:No 输出电流:55 mA 最大工作温度:+ 125 C 封装:Reel |
| NCV5500 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:500 mA Linear Regulator |
| NCV5500DADJR2G | 功能描述:低压差稳压器 - LDO LDO REG 500mA ADJ RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| NCV5500DT15RKG | 功能描述:低压差稳压器 - LDO ANA LDO REG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
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