參數(shù)資料
型號(hào)： LTC1628IG-SYNC#TR
廠商： LINEAR TECHNOLOGY CORP
元件分類(lèi)： 穩(wěn)壓器
英文描述： 3 A SWITCHING CONTROLLER, 360 kHz SWITCHING FREQ-MAX, PDSO28
封裝： 0.209 INCH, PLASTIC, SSOP-28
文件頁(yè)數(shù)： 6/32頁(yè)
文件大小： 658K
代理商： LTC1628IG-SYNC#TR
14
LTC1628-SYNC
1628syncfa
The inductor value also has secondary effects. The transi-
tion to Burst Mode operation begins when the average
inductor current required results in a peak current below
25% of the current limit determined by RSENSE. Lower
inductor values (higher
IL) will cause this to occur at
lower load currents, which can cause a dip in efficiency in
the upper range of low current operation. In Burst Mode
operation, lower inductance values will cause the burst
frequency to decrease.
Inductor Core Selection
Once the value for L is known, the type of inductor must
be selected. High efficiency converters generally cannot
afford the core loss found in low cost powdered iron
cores, forcing the use of more expensive ferrite,
molypermalloy, or Kool M
cores. Actual core loss is
independent of core size for a fixed inductor value, but it
is very dependent on inductance selected. As inductance
increases, core losses go down. Unfortunately, increased
inductance requires more turns of wire and therefore
copper losses will increase.
Ferrite designs have very low core loss and are preferred
at high switching frequencies, so design goals can con-
centrate on copper loss and preventing saturation. Ferrite
core material saturates “hard,” which means that induc-
tance collapses abruptly when the peak design current is
exceeded. This results in an abrupt increase in inductor
ripple current and consequent output voltage ripple. Do
not allow the core to saturate!
Molypermalloy (from Magnetics, Inc.) is a very good, low
loss core material for toroids, but it is more expensive than
ferrite. A reasonable compromise from the same manu-
facturer is Kool M
. Toroids are very space efficient,
especially when you can use several layers of wire. Be-
cause they generally lack a bobbin, mounting is more
difficult. However, designs for surface mount are available
that do not increase the height significantly.
Power MOSFET and D1 Selection
Two external power MOSFETs must be selected for each
controller in the LTC1628-SYNC: One N-channel MOSFET
for the top (main) switch, and one N-channel MOSFET for
the bottom (synchronous) switch.
The peak-to-peak drive levels are set by the INTVCC
voltage. This voltage is typically 5V during start-up (see
EXTVCC Pin Connection). Consequently, logic-level
threshold MOSFETs must be used in most applications.
The only exception is if low input voltage is expected
(VIN < 5V); then, sub-logic level threshold MOSFETs
(VGS(TH) < 3V) should be used. Pay close attention to the
BVDSS specification for the MOSFETs as well; most of the
logic level MOSFETs are limited to 30V or less.
Selection criteria for the power MOSFETs include the “ON”
resistance RDS(ON), reverse transfer capacitance CRSS,
input voltage and maximum output current. When the
LTC1628-SYNC is operating in continuous mode the duty
cycles for the top and bottom MOSFETs are given by:
Main Switch Duty Cycle
V
OUT
IN
=
Synchronous Switch Duty Cycle
VV
V
IN
OUT
IN
=
–
The MOSFET power dissipations at maximum output
current are given by:
P
V
IR
kV
I
C
f
MAIN
OUT
IN
MAX
DS ON
IN
MAX
RSS
=
() +
()
+
() ( )( )( )
2
1
δ
()
P
VV
V
IR
SYNC
IN
OUT
IN
MAX
DS ON
=
() +
()
–
()
2
1
δ
where
δ is the temperature dependency of RDS(ON) and k
is a constant inversely related to the gate drive current.
Both MOSFETs have I2R losses while the topside N-channel
equation includes an additional term for transition losses,
which are highest at high input voltages. For VIN < 20V the
high current efficiency generally improves with larger
MOSFETs, while for VIN > 20V the transition losses rapidly
increase to the point that the use of a higher RDS(ON) device
with lower CRSS actually provides higher efficiency. The
Kool M
is a registered trademark of Magnetics, Inc.
APPLICATIO S I FOR ATIO
WU
UU
相關(guān)PDF資料
PDF描述
LTC1643HCGN#PBF 4-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16
LTC1643LCGN#TR 4-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO16
LTC1728HS5-5 3-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5
LTC1729CS8-8.4#TR 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8
LTC1772BIS6#PBF 1 A SWITCHING CONTROLLER, 650 kHz SWITCHING FREQ-MAX, PDSO6
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC1628IUH 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LTC1628IUH#PBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LTC1628IUH#TR 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LTC1628IUH#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
LTC1629CG 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 標(biāo)準(zhǔn)包裝:4,500 系列:PowerWise® PWM 型:控制器 輸出數(shù):1 頻率 - 最大:1MHz 占空比:95% 電源電壓:2.8 V ~ 5.5 V 降壓:是 升壓:無(wú) 回掃:無(wú) 反相:無(wú) 倍增器:無(wú) 除法器:無(wú) Cuk:無(wú) 隔離:無(wú) 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤(pán) 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱(chēng):LM1771SSDX
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(xiě)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

*
*
*