參數(shù)資料
型號(hào)： L6727TR
廠商： 意法半導(dǎo)體
英文描述： Single phase PWM controller
中文描述： 單相PWM控制器
文件頁(yè)數(shù)： 13/22頁(yè)
文件大?。?/td> 318K
代理商： L6727TR
L6727
Over current protection
13/22
7
Over current protection
The over current feature protects the converter from a shorted output or overload, by
sensing the output current information across the Low Side MOSFET drain-source on-
resistance, R
dsON
. This method reduces cost and enhances converter efficiency by avoiding
the use of expensive and space-consuming sense resistors.
The low side R
dsON
current sense is implemented by comparing the voltage at the PHASE
node when LS MOSFET is turned on with the programmed OCP threshold voltage,
internally held. If the monitored voltage drop (GND to PHASE) exceeds this threshold, an
Over Current Event is detected. If two Over Current Events are detected in two consecutive
switching cycles, the protection will be triggered and the device will turn off both LS and HS
MOSFETs for 2048 clock cycles (plus internal SS remaining time, if triggered during a SS
phase); then it will begin a new Soft Start.
If the over current condition is not removed, the continuous fault will cause L6727 to go into
a hiccup mode with a typical period of 13.6ms (
Figure 5
), guaranteeing safe load protection
and very low power dissipation.
7.1
Over current threshold setting
When supplied with VCC = 5V, L6727 allows to easily program an Over Current Threshold
ranging from 50mV to 500mV, simply by adding a resistor (R
OCSET
) between COMP and
VCC.
During a short period of time (5.5ms - 6.5ms) following the first enable (given VCC over
UVLO threshold), an internal 60μA current (I
OCSET
) is sunk from COMP pin, determining a
voltage drop across R
OCSET
. This voltage drop, differentially sensed between VCC and
COMP, divided by a factor 3, will be sampled and internally held by the device as Over
Current Threshold until next VCC cycling. Differential sensing versus VCC allows OCSET
procedure to be fully independent from VIN rail. The OC setting procedure overall time
length ranges from 5.5ms to 6.5ms, proportionally to the threshold being set.
Connecting an R
OCSET
resistor between COMP and VCC, the programmed threshold will
be:
1
3
R
OCSET
values range from 2.5k
to 25k
.
If the voltage drop across R
OCSET
is too low, the system will be very sensitive to start-up
inrush current and noise. This can result in a continuous OCP triggering and hiccup mode.
In this case, consider to increase R
OCSET
value.
In case R
OCSET
is not connected (and VCC = 5V), the device will set the maximum
threshold.
If the device is supplied with a VCC higher than 7V, R
OCSET
must be not connected. In this
case, as soon as VCC rises over V
CC_OC
(8V typ.), L6727 switches OC threshold to 400mV
(internally fixed value).
See
Figure 5
for OC threshold setting and soft start oscilloscope sample waveforms.
I
OCth
--
I
R
R
dsON
-------------------------------------------
=
相關(guān)PDF資料
PDF描述
L6730CQ Adjustable step-down controller with synchronous rectification
L6730C Adjustable step-down controller with synchronous rectification
L6730CQTR Adjustable step-down controller with synchronous rectification
L6730CTR Adjustable step-down controller with synchronous rectification
L6730D Adjustable step-down controller with synchronous rectification
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6728 功能描述:DC/DC 開關(guān)控制器 Sngl phase PWM controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK
L6728_0706 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Single phase PWM controller with Power Good
L6728A 功能描述:電壓模式 PWM 控制器 Hi-Freq. singl-phase PWM controller w/Po 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
L6728AH 功能描述:軟開關(guān) PWM 控制器 Sgl Output 600 KHz DFPN-10 RoHS:否 制造商:Fairchild Semiconductor 輸出端數(shù)量: 輸出電流: 開關(guān)頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
L6728AHTR 功能描述:電流型 PWM 控制器 HIGH FREQ PWM CNTRL W/PO RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*