參數(shù)資料
型號： LTC3766IGN#TRPBF
廠商： LINEAR TECHNOLOGY CORP
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 316 kHz SWITCHING FREQ-MAX, PDSO28
封裝： 0.150 INCH, LEAD FREE, PLASTIC, SSOP-28
文件頁數(shù)： 28/60頁
文件大小： 607K
代理商： LTC3766IGN#TRPBF
LTC3766
34
3766f
APPLICATIONS INFORMATION
Another important consideration in setting the SGD delay
is the prevention of SWP collapse due to excessive FG
turn-off delay. After PG turn-off, the SWP node is quickly
driven high by the transformer leakage to a level of ap-
proximately VIN/(1 – D). Ideally, it should remain at this
voltage as FG turns off, SG turns on, and then AG turns
on. However, if the delay to FG turn-off is too long, the
SWP voltage will momentarily fall towards VIN, and it will
not rise again until being forced high by AG turn-on. This
collapse of the SWP node is illustrated in Figure 17, and
is more prominent at lighter loads.
It can significantly degrade efficiency as the SWP node
is discharged and recharged every cycle, but it is easily
avoided by further shortening the SGD delay. Although
the LTC3766 inhibits the SG turn-on until SW < 0.5V, this
is not true of the delay to FG turn-off. The delay from PT+
fallingtoFGturn-offcanbedecreasedbeyondtheadaptive
limit of SG turn-on, so that the FG and SG edges can be
separated with a small dead time between them. This is
important to allow the FG turn-off to be separately opti-
mized based upon circuit parasitics. In most applications,
a peak in full load efficiency is normally found with the
SGD delay set so that there is no SWP collapse and there
is a small dead time between FG turn-off and SG turn-on.
In applications where efficiency is less critical, this delay
can be set adaptively by tying SGD to GND. In this case,
FG falling and SG rising will both be inhibited until SW <
0.5V. For fixed delay mode, always use a resistor of 8k or
greater on the SGD pin to avoid activating the adaptive
delay mode.
Delay Resistor Selection: PG Turn-On Transition
The delays associated with the PG turn-on transition are
set by the DELAY pin on the LTC3765 and the FGD pin on
the LTC3766. At the beginning of the PWM on-time, the
LTC3766 will assert the PT+ pin high, and will then turn FG
on and SG off after a delay set by the resistor on the FGD
pin. On the primary side, the LTC3765 will immediately
turn off the AG MOSFET in response to PT+ rising, and it
will then turn on the PG MOSFET after a delay determined
by the resistor on the LTC3765 DELAY pin. The FGD delay
resistor on the secondary side must be selected in careful
coordination with the delay on the primary side; therefore,
the following procedure outlines how to choose compo-
nents for both the LTC3765 and LTC3766.
The first objective in setting the PG turn-on delays is to
minimize switching loss by turning on the PG and FG
MOSFETs at minimum drain voltage. After the AG MOSFET
has turned off, the PG and FG drain voltages (SWP and
SWB) will naturally ramp down to approximately VIN and
0V respectively. These voltages take 100ns to 500ns or
longer to fall, depending on the main transformer mag-
netizing inductance and the parasitic capacitance on the
MOSFET drains. Choosing the delay settings correctly
can significantly impact the power loss due to switching
the MOSFETs.
For a particular design, the most effective procedure is to
set the PG and FG delays based on the resulting waveform
on SWP and SWB. In order to evaluate these waveforms,
VIN
1 – D
~
VIN
1 – D
~
VIN
SWP NODE
AG
PT+
FG
AG
PT+
FG
tSGD TOO LONG
0V
VIN
0V
tSGD OK
3766 F17
Figure 17. Avoiding SWP Collapse from Long Delay
相關(guān)PDF資料
PDF描述
LTC3766MPUFD#PBF SWITCHING CONTROLLER, 316 kHz SWITCHING FREQ-MAX, PQCC28
LTC3766EUFD#PBF SWITCHING CONTROLLER, 316 kHz SWITCHING FREQ-MAX, PQCC28
LTC3805EDD SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10
LTC3805EMSE SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10
LTC3805HMSE#TR SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC3766IUFD#PBF 功能描述:IC CONTROLLER SYNCH 28QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源控制器，監(jiān)視器 系列:Direct Flux Limit™, PolyPhase® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 應(yīng)用:多相控制器 輸入電壓:- 電源電壓:9 V ~ 14 V 電流 - 電源:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（5x5） 包裝:帶卷 (TR)
LTC3766IUFD#TRPBF 功能描述:IC CONTROLLER SYNCH 28QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源控制器，監(jiān)視器 系列:Direct Flux Limit™, PolyPhase® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 應(yīng)用:多相控制器 輸入電壓:- 電源電壓:9 V ~ 14 V 電流 - 電源:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（5x5） 包裝:帶卷 (TR)
LTC3766MPGN#PBF 功能描述:IC CONTROLLER SYNCH 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電源控制器，監(jiān)視器 系列:Direct Flux Limit™, PolyPhase® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 應(yīng)用:多相控制器 輸入電壓:- 電源電壓:9 V ~ 14 V 電流 - 電源:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（5x5） 包裝:帶卷 (TR)
LTC3766MPGN#TRPBF 功能描述:IC CONTROLLER SYNCH 28SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 電源控制器，監(jiān)視器 系列:Direct Flux Limit™, PolyPhase® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 應(yīng)用:多相控制器 輸入電壓:- 電源電壓:9 V ~ 14 V 電流 - 電源:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（5x5） 包裝:帶卷 (TR)
LTC3766MPUFD#PBF 功能描述:IC CONTROLLER SYNCH 28QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 電源控制器，監(jiān)視器 系列:Direct Flux Limit™, PolyPhase® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:- 應(yīng)用:多相控制器 輸入電壓:- 電源電壓:9 V ~ 14 V 電流 - 電源:- 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:40-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:40-TQFN-EP（5x5） 包裝:帶卷 (TR)
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

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

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

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*