- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄30771 > LTC3856IUH#TRPBF (LINEAR TECHNOLOGY CORP) SWITCHING CONTROLLER, PQCC38 PDF資料下載
參數(shù)資料
| 型號： | LTC3856IUH#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, PQCC38 |
| 封裝： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD-X, QFN-32 |
| 文件頁數(shù)： | 10/40頁 |
| 文件大?。?/td> | 2222K |
| 代理商： | LTC3856IUH#TRPBF |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁當(dāng)前第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁第30頁第31頁第32頁第33頁第34頁第35頁第36頁第37頁第38頁第39頁第40頁
LTC3856
3856f
applicaTions inForMaTion
The LTC3856 also features a DCR temperature compensa-
tion circuit by using a NTC temperature sensor. See the
Inductor DCR Sensing Temperature Compensation and
the ITEMP Pin section for details.
The maximum power loss in R1 is related to duty cycle,
and will occur in continuous mode at the maximum input
voltage:
P
R
V
R
LOSS
IN MAX
OUT
1
=
(
)
(
)
Ensure that R1 has a power rating higher than this value.
If high efficiency is necessary at light loads, consider this
power loss when deciding whether to use DCR sensing or
sense resistors. Light load power loss can be modestly
higher with a DCR network than with a sense resistor, due
totheextraswitchinglossesincurredthroughR1.However,
DCR sensing eliminates a sense resistor, reduces conduc-
tion losses and provides higher efficiency at heavy loads.
Peak efficiency is about the same with either method. To
maintain a good signal-to-noise ratio for the current sense
signal, use a minimum
VSENSE of 10mV for duty cycles
less than 40%. For a DCR sensing application, the actual
ripple voltage will be determined by the equation:
=
V
R C
V
f
SENSE
IN
OUT
IN OSC
1 1
Inductor DCR Sensing Temperature Compensation
and the ITEMP Pin
Inductor DCR current sensing provides a lossless method
of sensing the instantaneous current. Therefore, it can
provide higher efficiency for applications of high output
currents. However, the DCR of the inductor, which is the
small amount of DC winding resistance of the copper,
typically has a positive temperature coefficient. As the
temperature of the inductor rises, its DCR value increases.
The current limit of the controller is therefore reduced.
The LTC3856 offers a method to counter this inaccuracy
by allowing the user to place an NTC temperature sensing
resistor near the inductor to actively correct this error.
The ITEMP pin, when left floating, is at a voltage around
5V and DCR temperature compensation is disabled. The
ITEMP pin has a constant 10A precision current flow-
ing out of the pin. By connecting an NTC resistor from
the ITEMP pin to SGND, the maximum current sense
threshold can be varied over temperature according the
following equation:
V
SENSEMAX ADJ
SENSE MAX
ITEMP
(
)
(
)
. –
.
=
1 8
1 3
where:
VSENSEMAX(ADJ)isthemaximumadjustedcurrentsense
threshold at temperature.
VSENSE(MAX) is the maximum current sense threshold
specified in the Electrical Characteristics table. It is
typically 75mV, 50mV or 30mV, depending on the set-
ting ILIM pins.
VITEMP is the voltage of the ITEMP pin.
The valid voltage range for DCR temperature compensa-
tion on the ITEMP pin is between 0.5V to 0.2V, with 0.5V
or above being no DCR temperature correction and 0.2V
the maximum correction. However, if the duty cycle of the
controller is less than 25%, the ITEMP range is extended
from 0.5V to 0V.
The NTC resistor has a negative temperature coefficient,
meaning its value decreases as temperature rises. The
VITEMP voltage, therefore, decreases as temperature in-
creases and in turn, the VSENSEMAX(ADJ) will increase to
compensate the DCR temperature coefficient. The NTC
resistor, however, is nonlinear and the user can linear-
ize its value by building a resistor network with regular
resistors. Consult the NTC manufacture data sheets for
detailed information.
Another use for the ITEMP pins, in addition to NTC com-
pensated DCR sensing, is adjusting VSENSE(MAX) to values
between the nominal values of 30mV, 50mV and 75mV
for a more precise current limit. This is done by applying
a voltage less than 0.5V to the ITEMP pin. VSENSE(MAX)
will be varied per the previous equation and the same
duty cycle limitations will apply. The current limit can be
adjusted using this method either with a sense resistor
or DCR sensing.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC3856EFE#TRPBF | SWITCHING CONTROLLER, PDSO38 |
| LTC3860IUH#PBF | DUAL SWITCHING CONTROLLER, 1250 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3862HUH#TRPBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, QCC24 |
| LTC3862IFE#PBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
| LTC3862HFE#PBF | DUAL SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO24 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3857EGN-1#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3857EGN-1#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別: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 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
| LTC3857EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:PolyPhase® 特色產(chǎn)品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 標(biāo)準(zhǔn)包裝:1 系列:PowerWise® PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1MHz 占空比:81% 電源電壓:4.5 V ~ 18 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-5°C ~ 125°C 封裝/外殼:32-WFQFN 裸露焊盤 包裝:Digi-Reel® 產(chǎn)品目錄頁面:1303 (CN2011-ZH PDF) 其它名稱:LM3754SQDKR |
| LTC3857EUH#PBF | 制造商:Linear Technology 功能描述:IC DUAL SYNC STEP-DOWN CONTROLLER QFN-32 |
| LTC3857EUH#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別: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 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:6-WDFN 裸露焊盤 包裝:帶卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名稱:LM1771SSDX |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。