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參數資料
| 型號： | LTC3614IUDD#PBF |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 10.5 A SWITCHING REGULATOR, 2700 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封裝： | 3 X 5 MM, LEAD FREE, PLASTIC, QFN-24 |
| 文件頁數： | 17/30頁 |
| 文件大小： | 438K |
| 代理商： | LTC3614IUDD#PBF |
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LTC3614
24
3614fa
APPLICATIONS INFORMATION
Thermal Considerations
In most applications, the LTC3614 does not dissipate much
heat due to its high efciency.
However, in applications where the LTC3614 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 160°C,
both power switches will be turned off and the SW node
will become high impedance.
To prevent the LTC3614 from exceeding the maximum
junction temperature, some thermal analysis is required.
The temperature rise is given by:
TRISE = (PD)(θJA)
where PD is the power dissipated by the regulator and
θJA is the thermal resistance from the junction of the die
to the ambient temperature. The junction temperature,
TJ, is given by:
TJ = TA + TRISE
where TA is the ambient temperature.
As an example, consider the case when the LTC3614 is in
dropout at an input voltage of 3.3V with a load current of
4A at an ambient temperature of 85°C. From the Typical
Performance Characteristics graph of Switch Resistance,
the RDS(ON) resistance of the P-channel switch is 0.038Ω.
Therefore, power dissipated by the part is:
PD = (IOUT)2 RDS(ON) = 0.61W
For the QFN package, the θJA is 38°C/W.
Therefore, the junction temperature of the regulator operat-
ing at 85°C ambient temperature is approximately:
TJ = 0.61W 38°C/W + 85°C = 108°C
We can safely assume that the actual junction temperature
will not exceed the absolute maximum junction tempera-
ture of 125°C.
Note that for very low input voltage, the junction tempera-
ture will be higher due to increased switch resistance,
RDS(ON). It is not recommended to use full load current
with high ambient temperature and low input voltage.
To maximize the thermal performance of the LTC3614 the
exposed pad should be soldered to a ground plane. See
the PCB Layout Board Checklist.
Design Example
As a design example, consider using the LTC3614 in an
application with the following specications:
VIN = 2.25V to 5.5V, VOUT = 1.8V, IOUT(MAX) = 4A, IOUT(MIN)
= 200mA, f = 2.6MHz.
Efciency is important at both high and low load current,
so Burst Mode operation will be utilized.
First, calculate the timing resistor:
RT =
3.82
11Hz
2.6MHz
k – 16k = 130kΩ
Next, calculate the inductor value for about 33% ripple
current at maximum VIN:
L =
1.8V
2.6MHz 1.3A
1–
1.8V
5.5V
= 0.35μH
Using a standard value of 0.33μH inductor results in a
maximum ripple current of:
ΔIL =
1.8V
2.6MHz 0.33μH
1–
1.8V
5.5V
= 1.41A
COUT will be selected based on the ESR that is required
to satisfy the output voltage ripple requirement and the
bulk capacitance needed for loop stability. For this design,
a 100μF ceramic capacitor is used with a X5R or X7R
dielectric.
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| LTC3615EFE#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 3A 24TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 設計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數:1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應商設備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
| LTC3615EFE-1#PBF | 功能描述:IC REG BUCK SYNC ADJ 3A 24TSSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 開關穩(wěn)壓器 系列:- 設計資源:Design Support Tool 標準包裝:1 系列:- 類型:升壓（升壓） 輸出類型:固定 輸出數:1 輸出電壓:3V 輸入電壓:0.75 V ~ 2 V PWM 型:- 頻率 - 開關:- 電流 - 輸出:100mA 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:SOT-23-5 細型，TSOT-23-5 包裝:剪切帶 (CT) 供應商設備封裝:TSOT-23-5 其它名稱:AS1323-BTTT-30CT |
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