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| 型号： | NCP1587ADR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 8/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 8-SOIC |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 220kHz |
| 占空比： | 80% |
| 电源电压： | 4.5 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： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
NCP1587, NCP1587A
APPLICATION SECTION
Input Capacitor Selection
The input capacitor has to sustain the ripple current
produced during the on time of the upper MOSFET, so it
must have a low ESR to minimize the losses. The RMS value
of this ripple is:
The above calculation includes the delay from comp
rising to when output voltage starts becomes valid.
To calculate the time of output voltage rising to when it
reaches regulation; D V is the difference between the comp
voltage reaching regulation and 0.9 V.
Iin RMS + I OUT D
(1 * D) ,
Output Capacitor Selection
C OUT V OUT
t SS
I ss
D V OUT ? DISCHARGE +
D I OUT 2 L OUT
2
C OUT
(V IN
D * V OUT )
where D is the duty cycle, Iin RMS is the input RMS current,
& I OUT is the load current. The equation reaches its
maximum value with D = 0.5. Loss in the input capacitors
can be calculated with the following equation:
P CIN + ESR CIN Iin RMS 2 ,
where P CIN is the power loss in the input capacitors &
ESR CIN is the effective series resistance of the input
capacitance. Due to large dI/dt through the input capacitors,
electrolytic or ceramics should be used. If a tantalum must
be used, it must by surge protected. Otherwise, capacitor
failure could occur.
Calculating Input Start-up Current
To calculate the input start up current, the following
equation can be used.
I inrush + ,
where I inrush is the input current during start-up, C OUT is the
total output capacitance, V OUT is the desired output voltage,
and t SS is the soft start interval.
If the inrush current is higher than the steady state input
current during max load, then the input fuse should be rated
accordingly, if one is used.
Calculating Soft Start Time
To calculate the soft start time, the following equation can
be used.
(C p ) C c ) * D V
t ss +
Where C c is the compensation as well as the soft start
capacitor,
C p is the additional capacitor that forms the second pole.
I ss is the soft start current
D V is the comp voltage from zero to until it reaches
regulation: ((d * ramp) + 0.9)
D V
The output capacitor is a basic component for the fast
response of the power supply. In fact, during load transient,
for the first few microseconds it supplies the current to the
load. The controller immediately recognizes the load
transient and sets the duty cycle to maximum, but the current
slope is limited by the inductor value.
During a load step transient the output voltage initial
drops due to the current variation inside the capacitor and the
ESR. ((neglecting the effect of the effective series
inductance (ESL)):
D V OUT ? ESR + D I OUT ESR COUT
where V OUT-ESR is the voltage deviation of V OUT due to the
effects of ESR and the ESR COUT is the total effective series
resistance of the output capacitors.
A minimum capacitor value is required to sustain the
current during the load transient without discharging it. The
voltage drop due to output capacitor discharge is given by
the following equation:
,
where V OUT-DISCHARGE is the voltage deviation of V OUT
due to the effects of discharge, L OUT is the output inductor
value & V IN is the input voltage.
It should be noted that Δ V OUT-DISCHARGE and
Δ V OUT-ESR are out of phase with each other, and the larger
of these two voltages will determine the maximum deviation
of the output voltage (neglecting the effect of the ESL).
Inductor Selection
Both mechanical and electrical considerations influence
the selection of an output inductor. From a mechanical
perspective, smaller inductor values generally correspond to
smaller physical size. Since the inductor is often one of the
largest components in the regulation system, a minimum
inductor value is particularly important in space-constrained
applications. From an electrical perspective, the maximum
current slew rate through the output inductor for a buck
regulator is given by:
900 mV
SlewRate LOUT +
V IN * V OUT
L OUT
Vcomp
Vout
This equation implies that larger inductor values limit the
regulator ’s ability to slew current through the output
inductor in response to output load transients. Consequently,
output capacitors must supply the load current until the
inductor current reaches the output load current level. This
results in larger values of output capacitance to maintain
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相关代理商/技术参数 |
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| NCP1587DR2G | 功能描述:电压模式 PWM 控制器 BUCK CONTROLLER RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| NCP1587EDR2G | 功能描述:电流型 PWM 控制器 BUCK CONTROLLER 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 |
| NCP1587GDR2G | 制造商:ON Semiconductor 功能描述:BUCK CONVERTER - Tape and Reel 制造商:ON Semiconductor 功能描述:REEL / BUCK CONVERTER |
| NCP1588MTR2G | 功能描述:IC REG CTRLR BUCK PWM VM 10-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:100% 电源电压:8.2 V ~ 30 V 降压:无 升压:无 回扫:是 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:0°C ~ 70°C 封装/外壳:8-DIP（0.300"，7.62mm） 包装:管件 产品目录页面:1316 (CN2011-ZH PDF) |
| NCP1589AMNTWG | 功能描述:电压模式 PWM 控制器 BUCK REGULATOR RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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