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| 型号： | LX1672-05CPWTR |
| 厂商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分类： | 稳压器 |
| 英文描述： | 1 A DUAL SWITCHING CONTROLLER, 575 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封装： | PLASTIC, TSSOP-28 |
| 文件页数： | 3/20页 |
| 文件大小： | 358K |
| 代理商： | LX1672-05CPWTR |
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 11
Copyright
2000
Rev. 0.3m, 2005-04-12
WWW
.Microse
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LX1672
Multiple Output LoadSHARE PWM
PRELIMINARY DATA SHEET
TM
TH EORY OF O PERAT ION (C ON TINUE D )
BI-PHASE, LOADSHARE ( ESR METHOD)
The first method is to change the ratio of the inductors
equivalent series resistance, (ESR). As can be seen in the previous
example, if the offset error is zero and the ESR of the two
inductors are identical, then the two inductor currents will be
identical.
To change the ratio of current between the two
inductors, the value of the inductor’s ESR can be changed to allow
more current to flow through one inductor than the other. The
inductor with the lower ESR value will have the larger current.
The inductor currents are directly proportional to the ratio of the
inductor’s ESR value.
The following circuit description shows how to select the
inductor ESR for each phase where a different amount of power is
taken from two different input power supplies. A typical setup will
have a +5V power supply connected to the phase 1 half bridge
driver and a +3.3V power supply connected to the phase 2 half
bridge driver. The combined power output for this core voltage is
18W (+1.5V @ 12A). For this example the +5V power supply will
supply 7W and the +3.3V power supply will supply the other 11W.
7W @ 1.5V is a 4.67A current through the phase 1 inductor. 11W
@ 1.5V is a 7.33A current through the phase 2 inductor.
The
ratio of inductor ESR is inversely proportional to the power level
split.
1
2
1
I
ESR
=
The higher current inductor will have the lower ESR value. If
the ESR of the phase 1 inductor is selected as 10m, then the ESR
value of the phase 2 inductor is calculated as:
m
4
.
6
m
10
33
.
7
67
.
4
=
×
A
Depending on the required accuracy of this power sharing;
inductors can be chosen from standard vendor tables with an ESR
ratio close to the required values. Inductors can also be designed
for a given application so that there is the least amount of
compromise in the inductor’s performance.
1.5V @ 12A
18W
6.4m
4.67A
7.33A
10m
1.5V +
46.7mV
L1
L2
+5V @ 7W
+3.3V @ 11W
VOUT
Figure 7
– Ratio LoadSHARE Using Inductor ESR
BI-PHASE, LOADSHARE ( FEEDBACK DIVIDER METHOD)
Sometimes it is desirable to use the same inductor in both phases
while having a much larger current in one phase versus the other. A
simple resistor divider can be used on the input side of the Low Pass
Filter that is taken off of the switching side of the inductors. If the
Phase 2 current is to be larger than the current in Phase 1; the resistor
divider is placed in the feedback path before the Low Pass Filter that
is connected to the Phase 2 inductor. If the Phase 2 current needs to
be less than the current in Phase 1; the resistor divider is then placed
in the feedback path before the Low Pass Filter that is connected to
the Phase 1 inductor.
As in Figure 7, the millivolts of DC offset created by the resistor
divider network in the feedback path, appears as a voltage generator
between the ESR of the two inductors.
A divider in the feedback path from Phase 2 will cause the
voltage generator to be positive at Phase 2. With a divider in the
feedback path of Phase 1 the voltage generator becomes positive at
Phase 1. The Phase with the positive side of the voltage generator
will have the larger current. Systems that operate continuously
above a 30% power level can use this method, a down side is that
that the current difference between the two inductors still flows
during a no load condition.
This produces a low efficiency condition during a no load or light
load state, this method should not be used if a wide range of output
power is required.
The following description and Figure 8 show how to determine
the value of the resistor divider network required to generate the
offset voltage necessary to produce the different current ratio in the
two output inductors. The power sharing ratio is the same as that of
Figure 7. The Offset Voltage Generator is symbolic for the DC
voltage offset between Phase 1 & 2. This voltage is generated by
small changes in the duty cycle of Phase 2. The output of the LPF is
a DC voltage proportional to the duty cycle on its input. A small
amount of attenuation by a resistor divider before the LPF of Phase 2
will cause the duty cycle of Phase 2 to increase to produce the added
offset at V2. The high DC gain of the error amplifier will force
LPF2 to always be equal to LPF1. The following calculations
determine the value of the resistor divider necessary to satisfy this
example.
AA
PP
LL
IICC
AA
TT
IIOO
NN
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PDF描述 |
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| LX1673-03CPWTR | 1 A SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PDSO20 |
| LX1673-03CLQTR | 1 A SWITCHING CONTROLLER, 345 kHz SWITCHING FREQ-MAX, PQCC20 |
| LX1673-09CPWTR | 1 A SWITCHING CONTROLLER, 1035 kHz SWITCHING FREQ-MAX, PDSO20 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LX1672-05CPW-TR | 制造商:Microsemi Corporation 功能描述:MOSFET DRVR 0.8V 1A 3-OUT HI/LO SIDE HALF BRDG NON-INV 28TSS - Tape and Reel |
| LX1672-06CLQ | 功能描述:IC REG CTRLR BUCK PWM VM 38MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:LoadSHARE™ 标准包装:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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:-40°C ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR) |
| LX1672-06CLQ-TR | 制造商:Microsemi Corporation 功能描述:MOSFET DRVR 0.8V 1A 3-OUT HI/LO SIDE HALF BRDG NON-INV 38MLP - Tape and Reel |
| LX1673 | 制造商:MICROSEMI 制造商全称:Microsemi Corporation 功能描述:High Frequency PWM Regulator |
| LX1673-03CLQ | 功能描述:IC REG DL BCK/LINEAR SYNC 20MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1） 功能:任何功能 输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 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:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR |
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