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參數(shù)資料
| 型號： | LTC3823IGN#TRPBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 4 A SWITCHING CONTROLLER, PDSO28 |
| 封裝： | 0.150 INCH, LEAD FREE, PLASTIC, SSOP-28 |
| 文件頁數(shù)： | 4/26頁 |
| 文件大小： | 302K |
| 代理商： | LTC3823IGN#TRPBF |
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LTC3823
12
3823fd
The resulting power dissipation in the MOSFETs at maxi-
mum output current are:
PTOP = DTOP IOUT(MAX)2 ρT(TOP) RDS(ON)(MAX)
+ k VIN2 IOUT(MAX) CRSS f
PBOT = DBOT IOUT(MAX)2 ρT(BOT) RDS(ON)(MAX)
Both MOSFETs have I2R losses and the top MOSFET in-
cludes an additional term for transition losses, which are
largest at high input voltages. The constant k = 1.7A–1 can be
used to estimate the amount of transition loss. The bottom
MOSFET losses are greatest when the bottom duty cycle is
near 100%, during a short-circuit or at high input voltage.
Operating Frequency
The choice of operating frequency is a tradeoff between
efciency and component size. Low frequency operation
improves efciency by reducing MOSFET switching losses
but requires larger inductance and/or capacitance in order
to maintain low output ripple voltage.
The operating frequency of LTC3823 applications is de-
termined implicitly by the one-shot timer that controls
the on-time, tON, of the top MOSFET switch. The on-time
is set by the current out of the ION pin and the voltage at
the VON pin according to:
t
V
I
pF
ON
VON
ION
=
()
10
Tying a resistor RON to SGND from the ION pin yields an
on-time inversely proportional to 1/3 VIN. The current out
of the ION pin is:
I
V
R
ION
IN
ON
=
3
For a step-down converter, this results in approximately
constant frequency operation as the input supply varies:
f
V
VR
pF
H
OUT
VON
ON
Z
=
(
)
[]
310
To hold frequency constant during output voltage changes,
tie the VON pin to VOUT. The VON pin has internal clamps
that limit its input to the one-shot timer. If the pin is tied
below 0.6V, the input to the one-shot is clamped at 0.6V.
Similarly, if the pin is tied above 4.8V, the input is clamped
at 4.8V. In high VOUTapplications,tieVONtoINTVCC.Figures
2a and 2b show how RON relates to switching frequency
for several common output voltages.
JUNCTION TEMPERATURE (°C)
–50
TNORMALIZED
ON-RESISTANCE
1.0
1.5
150
3823 F01
0.5
0
50
100
2.0
Figure 1. RDS(ON) vs Temperature
APPLICATIONS INFORMATION
RON (kΩ)
100
SWITCHING
FREQUENCY
(kHz)
1000
3823 F02a
VOUT = 3.3V
VOUT = 1.5V
VOUT = 2.5V
RON (kΩ)
10
100
SWITCHING
FREQUENCY
(kHz)
1000
100
1000
3823 F02b
VOUT = 3.3V
VOUT = 12V
VOUT = 5V
Figure 2a. Switching Frequency vs RON (VON = 0V)
Figure 2b. Switching Frequency vs RON (VON = INTVCC)
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC3823IUH#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:- 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 |
| LTC3823IUH#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN DC/DC CONTROLLER QFN32 |
| LTC3823IUH#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:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 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:24-WQFN 裸露焊盤 包裝:帶卷 (TR) |
| LTC3824EMSE | 制造商:Linear Technology 功能描述:DC DC Cntrlr Single-OUT Step Down 4V to 60V Input 10-Pin MSOP EP |
| LTC3824EMSE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 10-MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 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 |
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