参数资料
| 型号： | NCP5322ADWR2 |
| 厂商： | ON Semiconductor |
| 文件页数： | 25/31页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR BUCK 2PH STEPDWN 28SOIC |
| 产品变化通告： | Product Obsolescence 11/Feb/2009 |
| 标准包装： | 1 |
| 应用： | 控制器，高性能处理器 |
| 输入电压： | 4.5 V ~ 14 V |
| 输出数： | 2 |
| 输出电压： | 3.3V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 28-SOIC |
| 包装： | 剪切带 (CT) |
| 其它名称： | NCP5322ADWR2OSCT |
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NCP5322A
“wind up” is the cause of the overshoot. In this case the
output voltage will transition more slowly because COMP
spikes upward as shown in Figure 24. Too much loop
gain/bandwidth increase the risk of instability. In general,
one should use the lowest loop gain/bandwidth as possible
to achieve acceptable transient response ? this will insure
good stability. If C AMP is optimal the COMP pin will slew
quickly but not overshoot and the output voltage will
monotonically settle as shown in Figure 25.
After the control loop is tuned to provide an acceptable
transient response the steady?state voltage ripple on the
COMP pin should be examined. When the converter is
operating at full, steady?state load, the peak?to?peak
voltage ripple on the COMP pin should be less than 20 mV PP
as shown in Figure 26. Less than 10 mV PP is ideal. Excessive
ripple on the COMP pin will contribute to output voltage
jitter.
Figure 24. The Value of C AMP Is Too Low and the
Loop Gain/Bandwidth Too High. COMP Moves Too
Figure 26. At Full?Load (28 A) the Peak?to?Peak
Voltage Ripple on the COMP Pin Should Be Less
than 20 mV for a Well?Tuned/Stable Controller.
Higher COMP Voltage Ripple Will Contribute to
Output Voltage Jitter.
9. Current Limit Setting
When the output of the current sense amplifier (CO1 or
CO2 in the block diagram) exceeds the voltage on the I LIM
pin the part will enter hiccup mode. For inductive sensing,
the I LIM pin voltage should be set based on the inductor ’s
maximum resistance (R LMAX ). The design must consider
the inductor’s resistance increase due to current heating and
ambient temperature rise. Also, depending on the current
sense points, the circuit board may add additional resistance.
In general, the temperature coefficient of copper is +0.393%
per ° C. If using a current sense resistor (R SENSE ), the I LIM
pin voltage should be set based on the maximum value of the
sense resistor. To set the level of the I LIM pin:
Quickly, Which Is Evident from the Small Spike in Its
VILIM + (IOUT,LIM ) D ILo 2) @ R @ GILIM
(34)
Voltage When the Load Is Applied or Removed. The
Output Voltage Transitions More Slowly Because of
the COMP Spike.
Figure 25. The Value of C AMP Is Optimal. COMP Slews
Quickly Without Spiking or Ringing. V OUT Does Not
Overshoot and Monotonically Settles to Its Final Value.
where:
I OUT,LIM is the current limit threshold of the converter;
D I Lo /2 is half the inductor ripple current;
R is either (R LMAX + R PCB ) or R SENSE;
G ILIM is the current sense to I LIM gain.
For the overcurrent protection to work properly, the
current sense time constant (RC) should be slightly larger
than the RL time constant. If the RC time constant is too fast,
during step load changes the sensed current waveform will
appear larger than the actual inductor current and will
probably trip the current limit at a lower level than expected.
10. PWM Comparator Input Voltage
The voltage at the positive input terminal of the PWM
comparator (see Figure 10 or 12) is limited by the internal
voltage supply of the controller (3.3 V), the size of the
internal ramp, and the magnitude of the channel startup
offset voltage. To prevent the PWM comparator from
saturating, the differential input voltage from CS REF to CSn
(n = 1 or 2) must satisfy the following equation:
http://onsemi.com
25
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| NCP5322ADWR2G | 制造商:Rochester Electronics LLC 功能描述: 制造商:ON Semiconductor 功能描述: |
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| NCP5331FTR2 | 功能描述:DC/DC 开关控制器 2 Phase Buck w/Gate 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 |
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