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參數(shù)資料
| 型號： | L6917D |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | SO-28 |
| 文件頁數(shù)： | 3/27頁 |
| 文件大小： | 411K |
| 代理商： | L6917D |
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11/27
L6917
Current Reading and Over Current
The current flowing trough each phase is read using the voltage drop across the low side mosfets rDSON or
across a sense resistor (RSENSE) and internally converted into a current. The transconductance ratio is issued
by the external resistor Rg placed outside the chip between ISENx and PGNDSx pins toward the reading points.
The full differential current reading rejects noise and allows to place sensing element in different locations with-
out affecting the measurement’s accuracy. The current reading circuitry reads the current during the time in
which the low-side mosfet is on (OFF Time). During this time, the reaction keeps the pin ISENx and PGNDSx
at the same voltage while during the time in which the reading circuitry is off, an internal clamp keeps these two
pins at the same voltage sinking from the ISENx pin the necessary current.
The proprietary current reading circuit allows a very precise and high bandwidth reading for both positive and
negative current. This circuit reproduces the current flowing through the sensing element using a high speed
Track & Hold transconductance amplifier. In particular, it reads the current during the second half of the OFF
time reducing noise injection into the device due to the mosfet turn-on (See fig. 4).
Figure 4.
This circuit sources a constant 50
A current from the PGNDSx pin and keeps the pins ISENx and PGNDSx at
the same voltage. Referring to figure 4, the current that flows in the ISENx pin is then given by the following
equation:
Where RSENSE is an external sense resistor or the rdson, on of the low side mosfet and Rg is the transconduc-
tance resistor used between ISENx and PGNDSx pins toward the reading points; IPHASE is the current carried
by each phase and, in particular, the current measured in the middle of the oscillator period
The current information reproduced internally is represented by the second term of the previous equation as
follow:
Since the current is read in differential mode, also negative current information is kept; this allow the device to
check for dangerous returning current between the two phases assuring the complete equalization between the
phase’s currents.
From the current information of each phase, information about the total current delivered (IFB =IINFO1 +IINFO2)
and the average current for each phase (IAVG =(IINFO1 +IINFO2)/2 ) is taken. IINFOX is then compared to IAVG
to give the correction to the PWM output in order to equalize the current carried by the two phases.
R
SENSE
Rg
50
A
IISENx
I PHASE
Rg
LGATEX
ISENX
PGNDSX
ILS1
ILS2
Track & Hold
Total current
information
I
ISENx
50
A
R
SENSE IPHASE
R
g
----------------------------------------------
+
50
AI
INF Ox
+
==
I
INF O x
R
SENSE IPH ASE
R
g
----------------------------------------------
=
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| L6917DTR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| L6918 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5 BIT PROGRAMMABLE MULTIPHASE CONTROLLER |
| L6918A | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5 BIT PROGRAMMABLE MULTIPHASE CONTROLLER |
| L6918AD | 功能描述:DC/DC 開關控制器 Prog Multi-Phase Cnt RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| L6918ADTR | 功能描述:DC/DC 開關控制器 Prog Multi-Phase Cnt RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
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