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参数资料
| 型号： | L6615N |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDIP8 |
| 封装： | MINI, DIP-8 |
| 文件页数： | 5/20页 |
| 文件大小： | 394K |
| 代理商： | L6615N |
13/20
L6615
The last point is the design of the compensation network ZC(s) connected between the COMP pin and
ground.
Besides the power supply feedback loop, the current sharing system introduces another, outer loop. To
avoid interaction between them it is important to design the bandwidth of the sharing loop at least one or-
der of magnitude lower than the bandwidth of the power supply loop.
For the total system, the loop gain is:
where
APWR(s) is the transfer function of PWM controller and power stage (see fig. 11)
RLOAD is the equivalent load resistance
Typically the compensation network is built by a R-C series.
A resistor in series with CC is required to boost the phase margin of the load share loop. The zero is placed
at the load share loop crossover frequency, fC(SH).
If fC(SH) is the share loop crossover frequency, then:
5
CURRENT SENSE METHODS
Several are the methods to sense the power supply output current; the simplest one is to use a power
resistor (fig. 13a) but increasing load current could require expensive resistor to support the inherent pow-
er dissipation, imposing the use of several paralleled resistor.
Other methods to sense the output current are showed in fig. 13b and 13c:
1. RDS(ON): a power MOS is placed in series to the output and its channel resistance (RDS(ON)) is used
as sense resistor (fig 13a): the L6615 sense pins will be connected, through RG resistors to the drain
and to the source of the MOS. Besides providing the sense resistor, the FET is used as "ORing" el-
ement: driving properly its gate, it is possible isolate the power supply output from the load (the body
diode is reversed biased so it doesn't conduct).
This is useful whenever features like hot swap or hot plug are required; compared with the well-known
solution using ORing diode, the ORing FET greatly reduces the power dissipation, in particular:
where VF is the forward drop across the diode.
2. Current transformer: in case of very high load currents, a transformer allows sensing a smaller cur-
rent, obtained through a scaling factor equal to the transformer turn ratio. In this way, the sense re-
sistor power dissipation requirements can be less tight: obviously this is paid with the cost of the
transformer.
In fig. 13c it is showed the simplified output stage of a power supply in forward configuration: through
two current transformers the load current is reproduced in the sensing circuit scaled by a factor N.
RSENSE will read a ripple (at the switching frequency) superimposed on the average current value
that doesn't affect the correct behaviour of the current sharing system because its loop gain is de-
signed with a low bandwidth - at least 2 order of magnitude lower than the switching frequency - that
will cut this high frequency.
G
LOOP s
()
R
SENSE
R
CGA
R
G
--------------- G
M ZC s
()
R
ADJ
R
A
-------------- A
PWR s
()
1
R
LOA D
------------------
=
C
1
2
π f
CSH
()
--------------------------------
R
CGA
G
M
R
G
-----------------------------
R
ADJ
R
A
--------------
R
SENSE
R
LOAD
----------------------
A
PW R f
CSH
()
=
R
C
1
2
π f
CSH
() CC
---------------------------------------------
=
P
DIO DE
()
V
F
I
OUT
R
SE NSE
I
OUT
2
+
=
P
MOS
()
R
DS O N
() IOUT
2
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| L6622-01 | 制造商:HAMAMATSU 制造商全称:Hamamatsu Corporation 功能描述:130 KV MICROFOCUS X-RAY SOURCE |
| L-663 | 制造商:RHOMBUS-IND 制造商全称:Rhombus Industries Inc. 功能描述:CURRENT SENSE INDUCTOR |
| L6-6330 | 制造商: 功能描述: 制造商:undefined 功能描述: |
| L6660 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:MILLI-ACTUATOR DRIVER |
| L6668 | 功能描述:电流型 PWM 控制器 SMART PRIMARY CONTROLLER RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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