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| 型号： | LTC3565EMSE#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 16/22页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 10MSOP |
| 标准包装： | 50 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.6 V ~ 5 V |
| 输入电压： | 2.5 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 最高 4MHz |
| 电流 - 输出： | 1.25A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 10-MSOP 裸露焊盘 |
| 产品目录页面： | 1335 (CN2011-ZH PDF) |
LTC3565
APPLICATIONS INFORMATION
L =
? ? 1 ?
? = 2μH
Δ I L =
? ? 1 ?
? = 460mA
C OUT ≈ 2.5
= 25μF
lossesincludingdiodeconductionlossesduringdead-time
and inductor core losses, which generally account for less
than 2% total additional loss.
Thermal Considerations
In a majority of applications, the LTC3565 does not dis-
sipate much heat due to its high efficiency. However, in
applications where the LTC3565 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 LTC3565 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:
T RISE = P D ? θ JA
where P D is the power dissipated by the regulator and θ JA
is the thermal resistance from the junction of the die to
the ambient temperature.
The junction temperature, T J , is given by:
T J = T RISE + T AMBIENT
As an example, consider the case when the LTC3565 is
in dropout at an input voltage of 3.3V with a load current
of 1A. From the Typical Performance Characteristics
graph of Switch Resistance, the R DS(ON) resistance of the
P-channel switch is 0.160Ω. Therefore, power dissipated
by the part is:
P D = I OUT2 ? R DS(ON) = 160mW
The MSE package junction-to-ambient thermal resistance,
θ JA , will be in the range of about 40°C/W. Therefore, the
junction temperature of the regulator operating in a 70°C
ambient temperature is approximately:
T J = 0.16 ? 40 + 70 = 76.4°C
Remembering that the above junction temperature is
obtained from an R DS(ON) at 25°C, we might recalculate
the junction temperature based on a higher R DS(ON) since
it increases with temperature. However, we can safely as-
sume that the actual junction temperature will not exceed
the absolute maximum junction temperature of 125°C.
Design Example
As a design example, consider using the LTC3565 in a
portable application with a Li-Ion battery. The battery pro-
vides a V IN = 2.5V to 4.2V. The load requires a maximum
of 1.25A in active mode and 10mA in standby mode. The
output voltage is V OUT = 2.5V. Since the load still needs
power in standby, Burst Mode operation is selected for
good low load efficiency.
First, calculate the timing resistor for 1MHz operation:
R T = 1.21 ? 10 6 (10 3 ) –1.2674 = 190.8k
Use a standard value of 191k. Next, calculate the inductor
value for about 40% ripple current at maximum V IN :
2.5V ? 2.5V ?
1MHz ? 500mA ? 4.2V ?
Choosing the closest inductor from a vendor of 2.2μH,
results in a maximum ripple current of:
2.5V ? 2.5V ?
1MHz ? 2.2μH ? 4.2V ?
For cost reasons, a ceramic capacitor will be used. C OUT
selection is then based on load step droop instead of ESR
requirements. For a 5% output droop:
1.25A
1MHz ? (5% ? 2.5V)
The closest standard value is 22μF. Since the output
impedance of a Li-Ion battery is very low, C IN is typically
22μF. In noisy environments, decoupling SV IN from PV IN
with an R6/C8 filter of 1Ω/0.1μF may help, but is typically
not needed.
3565fc
16
For more information www.linear.com/LTC3565
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| LTC3565IDD#PBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC3565IDD#TRPBF | 功能描述:IC REG BUCK SYNC ADJ 1.25A 10DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
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