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参数资料
| 型号： | NCV8855BMNR2G |
| 厂商： | ON Semiconductor |
| 文件页数： | 19/24页 |
| 文件大小： | 0K |
| 描述： | IC REG QD BUCK/LINEAR 40QFN |
| 标准包装： | 1 |
| 拓扑： | 降压（降压）（2），线性（LDO）（2） |
| 功能： | 汽车无线电设备和仪表板电源 |
| 输出数： | 4 |
| 频率 - 开关： | 170kHz |
| 电压/电流 - 输出 1： | 控制器 |
| 电压/电流 - 输出 2： | 可调式，2.5A |
| 电压/电流 - 输出 3： | 控制器 |
| 带 LED 驱动器： | 无 |
| 带监控器： | 无 |
| 带序列发生器： | 是 |
| 电源电压： | 9 V ~ 18 V |
| 工作温度： | -40°C ~ 105°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-VFQFN 裸露焊盘 |
| 供应商设备封装： | 40-QFN（6x6） |
| 包装： | 标准包装 |
| 其它名称： | NCV8855BMNR2GOSDKR |
NCV8855
I D(avg) + IOUT2 1 *
VOUT2
D VOUT ESR + D IOUT
( D IOUT)
L
VIN min D MAX * VOUT
dI L V L
Inductor Slew Rate +
+
SMPS2 Diode Selection
The diode in SMPS2 provides the inductor current path
when the power switch turns off. This is known as the
non ? synchronous diode or commutation diode. The peak
reverse voltage is equal to the maximum operating input
voltage. The peak conducting current is determined by the
internal current limit. The average current can be calculated
from:
(eq. 10)
VIN_SW
However, the worse case diode average current occurs
during a short circuit condition. For a diode to survive an
indefinite short circuit condition, the current rating of the
diode should be equal to the maximum current limit which
is 3.6 A. Thus the MBRS4201T3 is the diode of choice.
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 SMPS system, a minimum inductor
value is particularly important in space ? constrained
applications. From an electrical perspective, smaller
inductor values correspond to faster transient response. The
maximum current slew rate through the output inductor for
a buck regulator is given by:
(eq. 11)
dt L
Where I L is the inductor current, L is the output
inductance, and V L is the voltage drop across the inductor.
This equation indicates 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 (or store) sufficient charge to
maintain regulation while the inductor current “catches up”
to the load. This results in larger values of output capacitance
to maintain tight output voltage regulation.
In contrast, smaller values of inductance increase the
SMPS Output Capacitor Selection
The output capacitor is a basic component for the fast
response of the power supply. In fact, during load transient,
for first few microseconds they supply the current to the
load. The controller recognizes the load transient and
proceeds to increase the duty cycle to its maximum.
Neglecting the effect of the ESL, the output voltage has a
first drop due to the ESR of the bulk capacitor(s).
ESR (eq. 13)
A lower ESR produces a lower D V during load transient.
In addition, a lower ESR produces a lower output voltage
ripple.
The voltage drop due to the output capacitor discharge can
be approximated using the following equation:
2
D VOUT discharge +
2 COUT
(eq. 14)
where, D MAX is the maximum duty cycle value, which is
90%. Although the ESR effect is not in phase with the
discharging of the output voltage, D VOUT (ESR) can be
added to D VOUT (discharge) to give a rough indication of the
maximum D VOUT during a transient condition. Simulation
can also help determine the maximum D VOUT; however, it
will ultimately have to be verified with the actual load since
the ESL effect is dependent on layout and the actual load’s
di/dt.
SMPS Input Capacitor Selection
The primary consideration for selecting the input
capacitor is input RMS current. However, since there are
two SMPS running out ? of ? phase with each other,
calculating the input RMS current can be complicated. The
graphs below shows how the input RMS current is affected
by differing phase angles between SMPS1 and SMPS2. The
plot below was generated with VOUT1 at 5 V with a load of
2 A and an output inductor value of 10 m H, and VOUT2 at
8 V with a load of 4 A and an output inductor value of 10 m H.
VOUT VOUT
I PP + FSW
1 *
regulator ’s maximum achievable slew rate and decrease the
necessary capacitance, at the expense of higher ripple
current.
In continuous conduction mode, the peak ? to ? peak ripple
current is calculated using the following equation:
(eq. 12)
L VBATT
From this equation it is clear that the ripple current
increases as L decreases, emphasizing the trade ? off between
dynamic response and ripple current.
For most applications, the inductor value falls in the range
between 2.2 m H and 22 m H. There are many magnetic
component vendors providing standard product
3.00
2.80
2.60
2.40
2.20
2.00
1.80
1.60
1.40
1.20
1.00
0.00
60.00
120.00 180.00 240.00 300.00 360.00
Phase (VOUT1 vs VOUT2)
9.00
10.00
11.00
12.00
13.00
14.00
15.00
16.00
17.00
18.00
lines suitable for SMPS1 and SMPS2’s requirements.
TDK offers the RLF12545 ? PF series inductors, which are
recommended for the automotive radio application.
http://onsemi.com
19
Figure 22. Irms vs Phase
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NCV8855BMNR2GEVB | 功能描述:电源管理IC开发工具 SMPS ASIC 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 |
| NCV8870 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Automotive Grade Non-Synchronous Boost Controller |
| NCV887000 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Automotive Grade Non-Synchronous Boost Controller |
| NCV887000D1R2G | 功能描述:低压差稳压器 - LDO Auto Grade Non-Sync Boost Controller 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 |
| NCV887001 | 制造商:ONSEMI 制造商全称:ON Semiconductor 功能描述:Automotive Grade Non-Synchronous Boost Controller |
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