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參數資料
| 型號： | LTC3543EDCB#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.3 A SWITCHING REGULATOR, 2250 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | 2 X 3 MM, 0.75 MM HEIGHT, LEAD FREE, PLASTIC, MO-229, DFN-6 |
| 文件頁數： | 6/20頁 |
| 文件大小： | 329K |
| 代理商： | LTC3543EDCB#PBF |
LTC3543
14
3543fa
1. The VIN quiescent current is due to two components: the
DC bias current as given in the Electrical Characteristics
and the internal main switch and synchronous switch
gate charge currents. The gate charge current results
from switching the gate capacitance of the internal power
MOSFET switches. Each time the gate is switched from
high to low to high again, a packet of charge, dQ, moves
from VINtoground.TheresultingdQ/dtisthecurrentout
of VIN that is typically larger than the DC bias current. In
continuous mode, IGATECHG = f(QT + QB) where QT and
QB are the gate charges of the internal top and bottom
switches. Both the DC bias and gate charge losses are
proportional to VIN and thus their effects will be more
pronounced at higher supply voltages.
2. I2R losses are calculated from the resistances of the
internal switches, RSW, and external inductor RL. In
continuous mode, the average output current owing
through inductor L is “chopped” between the main
switch and the synchronous switch. Thus, the series
resistance looking into the SW pin is a function of both
top and bottom MOSFET RDS(ON) and the duty cycle
(DC) as follows:
RSW = (RDS(ON)TOP DC) + (RDS(ON)BOT (1 – DC))
The RDS(ON) for both the top and bottom MOSFETs can
be obtained from the Typical Performance Characteristics
curves. Thus, to obtain I2R losses, simply add RSW to
RL and multiply the result by the square of the average
output current.
Other losses, including CINandCOUTESRdissipativelosses
and inductor core losses, generally account for less than
2% total additional loss.
Thermal Considerations
In most applications, the LTC3543 does not dissipate much
heat due to its high efciency. But, in applications where the
LTC3543 is running at high ambient temperature with low
supply voltage and high duty cycles, such as in dropout,
the heat dissipated may exceed the maximum junction
temperature of the part. If the junction temperature reaches
approximately 150°C, both power switches will be turned
off and the SW node will become high impedance.
To avoid the LTC3543 from exceeding the maximum junc-
tion temperature, the user will need to do some thermal
analysis. The goal of the thermal analysis is to determine
whether the power dissipated exceeds the maximum
junction temperature of the part. The temperature rise is
given by:
TR =
θJA PD
where PD is the power dissipated by the regulator and
θJA is the thermal resistance from the junction of the die
to the temperature.
The junction temperature, TJ, is given by:
TJ = TA + TR
where TA is the ambient temperature.
As an example, consider the LTC3543 in dropout at an
input voltage of 2.7V, an ambient temperature of 80°C, and
a load current of 600mA. From the typical performance
graph of switch resistance, the RDS(ON) of the P-channel
switch at 80°C is approximately 0.41
Ω. There, power
dissipated by the part is:
PD = ILOAD2 RDS(ON) = 147.6mW
For the DFN package, the
θJA is 64°C/W. Thus, the junction
temperature of the regulator is:
TJ = 80°C + 0.1476 64 = 89.4°C
which is well below the maximum junction temperature of
125°C. Note that at higher supply voltages, the junction
temperature is lower due to reduced switch resistance
(RDS(ON)).
APPLICATIONS INFORMATION
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| LTC3544BEUD#TR | 0.8 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC16 |
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相關代理商/技術參數 |
參數描述 |
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| LTC3544 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544B | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544BEUD | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA |
| LTC3544BEUD#PBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:250 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:1.2V 輸入電壓:2.05 V ~ 6 V PWM 型:電壓模式 頻率 - 開關:2MHz 電流 - 輸出:500mA 同步整流器:是 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:6-UFDFN 包裝:帶卷 (TR) 供應商設備封裝:6-SON（1.45x1） 產品目錄頁面:1032 (CN2011-ZH PDF) 其它名稱:296-25628-2 |
| LTC3544BEUD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ QUAD 16QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 標準包裝:2,500 系列:- 類型:降壓（降壓） 輸出類型:固定 輸出數:1 輸出電壓:1.2V，1.5V，1.8V，2.5V 輸入電壓:2.7 V ~ 20 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:50mA 同步整流器:是 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-TFSOP，10-MSOP（0.118"，3.00mm 寬）裸露焊盤 包裝:帶卷 (TR) 供應商設備封裝:10-MSOP 裸露焊盤 |
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