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参数资料
| 型号： | LT3507AIUHF#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PQCC38 |
| 封装： | 5 X 7 MM, LEAD FREE, PLASTIC, QFN-38 |
| 文件页数： | 16/28页 |
| 文件大小： | 372K |
| 代理商： | LT3507AIUHF#PBF |
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LT3507A
23
3507af
The LDO pass transistor power is:
PNPN = IOUTLDO(VC – VOUTLDO)
where VC is the collector voltage on the NPN pass tran-
sistor.
Example: An LT3507A design requirements are:
VIN = 8V, f= 500kHz
V1 = 2.5V at I1 = 1.6A
V2 = 3.3V at I2 = 0.8A (used for boost, bias and V4)
V3 = 1.2V at I3 = 1A
V4 = 3V at I4 = 0.2A (from 3.3V output)
TA = 50°C, TJMAX = 125°C
θJA = 34°C/W
Schottky VF = 0.45V and Inductor ESR = 0.05Ω
PDISS(MAX) =
125
°C – 50°C
34
°C/W
= 2.2W
PSWDC1=
0.18
Ω 1.6A
(
)22.5V
8V
= 0.14W
PSWAC1=17ns 1.6A
(
) 8V
( ) 500k
(
)=0.11W
PBST1=
2.5V 3.3V
(
) 1.6A
50
+ 0.02A
8V
= 0.06W
Similarly, PSWDC2 = 0.09W, PSWAC2 = 0.07W, PBST2 =
0.06W, PSWDC3 = 0.03W, PSWAC3 = 0.07W and PBST2 =
0.03W. Remember, the total current from channel 2 is I2
+ I4 since the LDO pass transistor draws from V2. Ignore
bias and boost currents.
PQ = 8V 3.5mA
(
)+3.3V 7.5mA
(
)=0.05W
PLDO = 8V
0.2A
100
= 0.02W
APPLICATIONS INFORMATION
The total dissipation on the LT3507A is the sum of all these
and is equal to 0.73W. Note that this is less than half of
PDISS(MAX). Next, the power dissipation of the external
components are:
PDIODE1=
0.45V 8V – 2.5V – 0.45
(
)1.6A
8V
= 0.46W
PIND1= 1.6A
(
)20.05Ω=0.13W
Similarly, PDIODE2 = 0.24W, PIND2 = 0.05W, PDIODE3 =
0.36W and PIND3 = 0.05W. And finally:
PNPN = 0.2A(3.3V – 3V) = 0.06W
ThusthetotalpowerdissipatedbytheLT3507Aandexternal
components is 2.08W. The thermal analysis will use these
power dissipations to calculate the internal component
temperatures. Make sure that none of the components
exceed their rated temperature limits.
RELATED LINEAR TECHNOLOGY PUBLICATIONS
Application Notes 19, 35, 44, 76 and 88 contain more
detailed descriptions and design information for buck
regulators and other switching regulators. The LT1375
data sheet has a more extensive discussion of output
ripple, loop compensation, and stability testing. Design
Note 318 shows how to generate a dual polarity output
supply using a buck regulator.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3507EUHF#2ESPBF | 制造商:Linear Technology 功能描述:TRIPLE MONOLITHIC STEP-DOWN REGULATOR WITH LDO |
| LT3507EUHF#PBF | 功能描述:IC REG QD BUCK/LINEAR 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LT3507EUHF#TRPBF | 功能描述:IC REG QD BUCK/LINEAR 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LT3507EUHFPBF | 制造商:Linear Technology 功能描述:Step Down Regulator with LDO |
| LT3507EUHF-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Triple Monolithic Step-Down Regulator with LDO |
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