参数资料
| 型号： | EL7571CM |
| 厂商： | Intersil |
| 文件页数： | 10/19页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR PWM PROGRAMMABLE 20SOIC |
| 标准包装： | 38 |
| 应用： | 控制器，Intel Pentium? II，Pro |
| 输入电压： | 4.5 V ~ 12.6 V |
| 输出数： | 2 |
| 输出电压： | 1.3 V ~ 3.5 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 20-SO |
| 包装： | 管件 |
EL7571
? V OUT = ? ESR OUT × ? I OUT + ESL × ----- ?
P D = ? ------------- ? ? ESR IN
P = C × V × F
Input Capacitor, C 1
In a buck converter, where the output current is greater than
10A, significant demand is placed on the input capacitor.
Under steady state operation, the high side FET conducts
only when it is switched “on” and conducts zero current when
it is turned “off ”. The result is a current square wave drawn
from the input supply. Most of this input ripple current is
supplied from the input capacitor C 1 . The current flow
through C 1 ’s equivalent series resistance (ESR) can heat up
the capacitor and cause premature failure. Maximum input
ripple current occurs when the duty cycle is 50%, a current
of I OUT /2 RMS.
Worst case power dissipation is:
I OUT 2
? 2 ?
where:
ERS IN = input capacitor ESR
For safe and reliable operation, P D must be less than the
capacitor’s data sheet rating.
Input Inductor, L 2
The input inductor (L 2 ) isolates switching noise from the
input supply line by diverting buck converter input ripple
current into the input capacitor. Buck regulators generate
high levels of input ripple current because the load is
connected directly to the supply through the top switch every
cycle, chopping the input current between the load current
and zero, in proportion to the duty cycle. The input inductor
is critical in high current applications where the ripple current
is similarly high. An exclusively large input inductor degrades
the converter’s load transient response by limiting the
maximum rate of change of current at the converter input. A
1.5μH input inductor is sufficient in most applications.
Output Capacitor, C 2
During steady state operation, output ripple current is much
less than the input ripple current since current flow is
continuous, either via the top switch or the bottom switch.
Consequently, output capacitor power dissipation is less of a
concern than the input capacitor’s. However, low ESR is still
required for applications with very low output ripple voltage
or transient response requirements. Output ripple voltage is
given by:
V RIP = I RIP × ESR OUT
where:
I RIP = output ripple current
ESR OUT = output capacitor ESR
During a transient response, the output voltage spike is
determined by the ESR and the equivalent series inductance
10
(ESL) of the output capacitor in addition to the rate of change
and magnitude of the load current step. The output voltage
transient is given by:
? d i ?
? d t ?
where:
ESR OUT = output capacitor ESR
ESL = output capacitor ESL
? I OUT = output current step
d i /d t = rate of change of output current
Power MOSFET, Q 1 and Q 2
The EL7571 incorporates a boot-strap gate drive scheme to
allow the usage of N-channel MOSFETs. N-channel
MOSFETs are preferred because of their relative low cost
and low on resistance. The largest amount of the power loss
occurs in the power MOSFETs, thus low on resistance
should be the primary characteristic when selecting power
MOSFETs. In the boot-strap gate drive scheme, the gate
drive voltage can only go as high as the supply voltage,
therefore in a 5V system, the MOSFETs must be logic level
type, V GS <4.5V. In addition to on resistance and gate to
source threshold, the gate to source capacitance is also very
important. In the region when the output current is low
(below 5A), switching loss is the dominant factor. Switching
loss is determined by:
2
where:
C is the gate to source capacitance of the MOSFET
V is the supply voltage
F is the switching frequency
Another undesirable reason for a large MOSFET gate to
source capacitance is that the on resistance of the MOSFET
driver can not supply the peak current required to turn the
MOSFET on and off fast. This results in additional MOSFET
conduction loss. As frequency increases, this loss also
increases which leads to more power loss and lower
efficiency.
Finally, the MOSFET must be able to conduct the maximum
current and handle the power dissipation.
The EL7571 is designed to boot-strap to 12V for 12V only
input converters. In this application, logic level MOSFETs
are not required.
The following table below lists a few popular MOSFETs and
their critical specifications.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| EL7571CM-T13 | 功能描述:IC CTRLR PWM PROGRAMMABLE 20SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
| EL7571CMZ | 功能描述:IC CTRLR PWM PROGRAMMABLE 20SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
| EL7571CMZ-T13 | 功能描述:IC CTRLR PWM PROGRAMMABLE 20SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 专用型 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,000 系列:- 应用:电源，ICERA E400，E450 输入电压:4.1 V ~ 5.5 V 输出数:10 输出电压:可编程 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:42-WFBGA，WLCSP 供应商设备封装:42-WLP 包装:带卷 (TR) |
| EL7581 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:3-Channel DC-DC Converter |
| EL7581_06 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:3-Channel DC/DC Converter |
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