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参数资料
| 型号： | NCP3121QPBCKGEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 17/41页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR NCP3121QPBCKG |
| 设计资源： | NCP3121 EVB BOM NCP3121QPBCKGEVB Gerber Files NCP3121QPBCKGEVB Schematic |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 2，非隔离 |
| 输出电压： | 3.3V，5V |
| 电流 - 输出： | 3A，3A |
| 输入电压： | 12V |
| 稳压器拓扑结构： | 降压 |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | NCP3121 |
| 其它名称： | NCP3121QPBCKGEVBOS |
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NCP3121
Table 3. Schottky Diode Example
Part Number
Description
V RRM min
V F max
I O(rec) max
Package
Web
[V]
[V]
[A]
MBRA340T3G
MBRS340T3G
MBRS330T3G
3 A, 40 V Schottky Rectifier
3 A, 40 V Schottky Rectifier
3 A, 30 V Schottky Rectifier
40
40
30
0.45
0.5
0.5
3
3
3
SMA
SMC
SMC
www.onsemi.com
www.onsemi.com
www.onsemi.com
@ 1 * OUT @ ESR )
D V OUT +
V OUT ) V D
V IN ) V D * V DSAT
I RMS +
C OUT +
@ OUT @ 1 * OUT
V IN
V IN
f SW @ D V IN
C SS [
The worst case of the diode average current occurs during
maximum load current and maximum input voltage. The
rectifying diodes should be placed close to the SW pin to
avoid the possibility of ringing due to trace inductance.
Input Capacitor
The input current to the step down converter is
discontinuous. The input capacitor has to maintain the DC
input voltage and to sustain the ripple current produced by
internal MOSFET switching. For stable operation of the
switch mode converter, a low ESR capacitor is needed to
prevent large voltage transients from appearing at the input.
Therefore, ceramic capacitors are preferred, but the circuit
works in a stable manner also with electrolytic capacitors. It
must be located near the regulator and use short leads. Also,
paralleling ceramic capacitors will increase the regulator
stability.
The RMS value of the input capacitor current ripple is:
I RMS + I LOAD D(1 * D)
The duty cycle is:
D +
where:
V D is the voltage drop across the rectifying diode and
V DSAT is the switch saturation voltage on the power
MOSFET.
The equation reaches its maximum value with duty cycle
= 0.5, where:
I LOAD
2
Losses in the input capacitor can be calculated using the
following equation:
P CIN + I RMS 2 @ ESR CIN
where:
ESR CIN is the effective series resistance of the input
capacitance.
The input capacitor voltage ripple depends on the C IN
capacitor value. Therefore, the input capacitor can be
estimated by:
I LOAD V V
C IN +
Output Capacitor
principle consideration for the output capacitor is the ripple
current induced by the switches through the inductor. It
supplies the current to the load in DCM or during load
transient and filters the output voltage ripple. For low output
ripple voltage and good stability, low ESR output capacitors
are recommended. The inductor ripple current acting against
the ESR of the output capacitor is the major contributor to
the output ripple voltage.
An output capacitor has two main functions: it filters the
output and provides regulator loop stability.
The ESR of the output capacitor and the peak ? to ? peak
value of the inductor ripple current are the main factors
contributing to the output ripple voltage value.
The output voltage ripple is given by the following
equation:
V OUT V 1
f SW @ L V IN 8 @ f SW @ C OUT
where:
ESR is the equivalent series resistance of the output
capacitor.
The output capacitor value can by expressed by:
D I L
8 @ f SW @ D V OUT * D I L @ ESR
These components must be selected and placed carefully
to yield optimal results. Key specifications for output
capacitors are their ESR (equivalent series resistance) and
ESL (equivalent series inductance) values. For best transient
response, a combination of low value/high frequency and
bulk capacitors placed close to the load will be required.
For most applications, a 22 m F ceramic capacitor should
be sufficient. X5R or X7R dielectrics ceramic capacitors are
recommended.
Soft ? Start Capacitor Selection
The soft ? start time is programmed by an external
capacitor connected from the SS pin to AGND, which can
be calculated by:
t SS @ 8.75 m A
0.8 V
where:
? t SS is the soft ? start/stop interval.
Note: See the “Sequencing and Tracking” section on how
to use this capacitor.
The output capacitor filters output inductor ripple current
and provides low impedance for load current changes. The
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相关代理商/技术参数 |
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|---|---|
| NCP3122MNTXG | 功能描述:直流/直流开关调节器 Dual 2.0 Switching Regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| NCP3122QPBCKGEVB | 功能描述:电源管理IC开发工具 NCP3122 2A HF BUCK DB 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 |
| NCP3123MNTXG | 功能描述:直流/直流开关调节器 Dual 3.0 A Switching Regulator RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| NCP3123MNTXG-CUT TAPE | 制造商:ON 功能描述:NCP3123 Series 13.2 V Dual 3 A Step-Down DC/DC Switching Regulator - QFN-32 |
| NCP3123QPBCKGEVB | 功能描述:电源管理IC开发工具 NCP3123 3A HF BUCK DB 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 |
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