參數(shù)資料
型號(hào)： ISL6211
廠商： Intersil Corporation
英文描述： Crusoe⑩ Processor Core-Voltage Regulator
中文描述： 克魯索⑩處理器核心電壓調(diào)節(jié)器
文件頁(yè)數(shù)： 13/16頁(yè)
文件大?。?/td> 257K
代理商： ISL6211
13
ISL6211
MOSFET Selection and Considerations
Requirements for the upper and lower MOSFETs are
different in mobile applications. The reason for that is the
10:1 difference in conduction time of the lower and the upper
MOSFETs driven by a difference between the input voltage
which is nominally in the range from 8V to 20V, while
nominal output voltage is usually lower than 1.5V.
Requirements for the lower MOSFET are simpler than
those to the upper one. The lower the Rdson of this device,
the lower the conduction losses, the higher the converter’s
efficiency. Switching losses and gate drive losses are not
significant because of zero-voltage switching conditions
inherent for this device in the buck converter. Low reverse
recovery charge of the body diode is important because it
causes shoot-trough current spikes when the upper
MOSFET turns on. Also, important is to verify that the lower
MOSFET gate voltage does not reach threshold when high
dV/dt transition occurs on the phase node. To minimize this
effect, ISL6211 has a low, 0.8
typical, pull-down
resistance of the synchronous rectifier driver.
Requirements for the upper MOSFET Rdson are less
stringent than for the lower MOSFET because its conduction
time is significantly shorter and switching losses are
predominant especially at higher input voltages. It is
recommended to have approximately equal conduction losses
in the lower MOSFET and the switching losses in the upper
MOSFET at the nominal input voltage and load current. Then
the maximum of the converter efficiency is tuned to the
operating point where it is most desired. Also, this provides
the most cost effective solution.
Precise calculation of power dissipation in the MOSFETs is
very complex because many parameters affecting turn-on
and turn-off times such as gate reverse transfer charge, gate
internal resistance, body diode reverse recovery charge,
package and layout impedances and their variation with the
operation conditions are not available to a designer. The
following equations are provided only for rough estimation of
the power losses and should be accompanied by a detailed
breadboard evaluation. Attention should be paid to the input
voltage extremes where power dissipation in the MOSFETs
is usually higher.
Table 2 provides some component information for several
typical applications. Applications 2 and 3 intended for CPUs
other than Transmeta’s Crusoe.
Output Capacitor Selection
The output capacitor serves two major functions in a
switching power supply. Along with the inductor it filters the
sequence of pulses produced by the switcher, and it
supplies the load transient currents. The filtering
requirements are a function of the switching frequency and
the ripple current allowed, and are usually easy to satisfy in
high frequency converters.
The load transient requirements are a function of the slew
rate (di/dt) and the magnitude of the transient load current.
Modern microprocessors produce transient load rates in
excess of 10A/
μ
s. High frequency ceramic capacitors placed
beneath the processor socket initially supply the transient
and reduce the slew rate seen by the bulk capacitors. The
bulk capacitor values are generally determined by the total
allowable ESR rather than actual capacitance requirements.
High frequency decoupling capacitors should be placed as
close to the processor power pins as physically possible.
Consult with the processor manufacturer for specific
decoupling requirements. Use only specialized low-ESR
electrolytic capacitors intended for switching-regulator
applications for the bulk capacitors. The bulk capacitor’s
ESR will determine the output ripple voltage and the initial
voltage drop after a transient. In most cases, multiple
electrolytic capacitors of small case size perform better than
a single large case capacitor.
Pupper
2
-----------------------------------------------------
-----------------------------------------------------+
)
+
=
Plower
Io
2
Rdson
×
1
-------------
–
×
=
TABLE 2.
COMPONENT
APPLICATION
1
APPLICATION
2
APPLICATION
3
Maximum CPU
Current
6.0A
12.0A
18.0A
Inductor
1.8
μ
H
Sumida
CEP1231R8MH
1.0
μ
H
Panasonic
ETQP6F1R0BFA
0.8
μ
H
Panasonic
ETQP6F0R8BFA
Output
Capacitor
4x220
μ
F
Sanyo POSCAP
2R5TPC220M
or
3x270
μ
F
Panasonic
EEFUE0271R
6x220
μ
F
Sanyo POSCAP
2R5TPC220M
or
5x270
μ
F
Panasonic
EEFUE0271R
6x270
μ
F
Panasonic
EEFUE0D271R
High-Side
MOSFET
uPA1707
HUF76112SK8
2x
HUF76112SK8
Low-Side
MOSFET
uPA1707
2x
ITF86130SK8T
2x
ITF86130SK8T
Current-Input
Resistor for
~3
%
Droop
3.57k
2.80k
3.00k
相關(guān)PDF資料
PDF描述
ISL6211CA Octal D-Type Edge-Triggered Flip-Flops With 3-State Outputs 20-TSSOP -40 to 85
ISL6211CA-T Crusoe⑩ Processor Core-Voltage Regulator
ISL6219A Microprocessor CORE Voltage Regulator Precision Multi-Phase BUCK PWM Controller for Mobile Applications
ISL6219ACA Microprocessor CORE Voltage Regulator Precision Multi-Phase BUCK PWM Controller for Mobile Applications
ISL6219ACA-T Octal D-Type Edge-Triggered Flip-Flops With 3-State Outputs 20-TSSOP -40 to 85
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ISL6211CA 制造商:Rochester Electronics LLC 功能描述:CPU REGULATOR FOR TRANSMETA,SINGLE CORE - Bulk 制造商:Intersil Corporation 功能描述:
ISL6211CA WAF 制造商:Intersil Corporation 功能描述:
ISL6211CA-T 制造商:Rochester Electronics LLC 功能描述:CPU REGULATOR FOR TRANSMETA,SINGLE CORE - Tape and Reel 制造商:Intersil Corporation 功能描述:
ISL6215CA 制造商:Rochester Electronics LLC 功能描述:C4AM,PRECISION MULTI-PHASE BUCK PWM CONT - Bulk
ISL6215CA-T 功能描述:電壓模式 PWM 控制器 C4AM,PRECISION MULTI-PHASE BUCK PWM CONT RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
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