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| 型号： | LT1507CS8-3.3#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/20页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 3.3V 1.5A 8SOIC |
| 标准包装： | 100 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 3.3V |
| 输入电压： | 4 V ~ 15 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 500kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 8-SOIC |
| 产品目录页面： | 1327 (CN2011-ZH PDF) |
LT1507
APPLICATIO N S I N FOR M ATIO N
Example: with V IN = 5V, V OUT = 3.3V, I OUT = 1A;
2.0
GAIN (A/V)
80
( ) ( )
( 0 . 4 )( 1 ) ( 3 . 3 ) ?
+ 16 10 ? 9 ? ( 1 )( 5 ) ? 500 10 3 ?
??
??
??
??
P SW =
P BOOST = ( 3 . 3 ) ? 0 . 008 +
= 0 . 046 W
2
5
= 0 . 26 + 0 . 04 = 0 . 3 W
2 ? 1 ?
?
5 ? 75 ?
P Q = 5 ( 0 . 003 ) + 3 . 3 ( 0 . 005 ) = 0 . 032 W
1.5
1.0
0.5
0
V OUT = 3.3V
I OUT = 250mA
V IN = 5V
L = 10 μ H
PHASE
40
0
–40
–80
Total power dissipation is 0.3 + 0.046 + 0.032 = 0.38W.
10
100
1k 10k
FREQUENCY (Hz)
100k
LT1507 ? F08
Thermal resistance for the LT1507 packages is influenced
by the presence of internal or backside planes. With a full
plane under the SO package, thermal resistance will be
about 120 ° C/W. No plane will increase resistance to about
150 ° C/W. To calculate die temperature, use the proper
thermal resistance number for the desired package and
add in worst-case ambient temperature;
T J = T A + θ JA (P TOT )
With the S8 package ( θ JA = 120 ° C/W) at an ambient
temperature of 70 ° C;
T J = 70 + 120(0.38) = 116 ° C
FREQUENCY COMPENSATION
The LT1507 uses a “current mode” architecture to help
alleviate phase shift created by the inductor. The basic
Figure 8. Phase and Gain from V C Pin Voltage
to Inductor Current
parallel with 12pF. In all practical applications, the com-
pensation network from V C pin to ground has a much
lower impedance than the output impedance of the ampli-
fier at frequencies above 500Hz. This means that the error
amplifier characteristics themselves do not contribute
excess phase shift to the loop and the phase/gain charac-
teristics of the error amplifier section are completely
controlled by the external compensation network.
The complete small-signal model is shown in Figure 9. R1
and R2 are the divider used to set output voltage. These are
internal on the fixed voltage LT1507-3.3 with R1 = 1.8k
and R2 = 5k. R C , C C and C F are external compensation
connections are shown in Figure 9. Gain of the power stage
can be modeled as 1.8A/V transconductance from the V C
POWER STAGE
g m = 1.8A/V
LT1507
V SW
L1
OUTPUT
pin voltage to current delivered to the output. This is
shown in Figure 8 where the transconductance from V C
12pF
ERROR AMPLIFIER
g m = 2000 μ ho
F B
R1
pin to inductor current is essentially flat from 50Hz to
50kHz and phase shift is minimal in the important loop
unity-gain band of 1kHz to 50kHz. Inductor variation from
3 μ H to 20 μ H will have very little effect on these curves.
Overall gain from the V C pin to output is then modeled as
the product of 1.8A/V transconductance multiplied by the
complex impedance of the load in parallel with the output
capacitor model.
200k
GND
C F
V C
R C
C C
2.42V
R2
ESR
+
C1
1507 ? F09
The error amplifier can be modeled as a transconductance
of 2000 μ mho, with an output impedance of 200k ? in
18
Figure 9. Small-Signal Model for Loop Stability Analysis
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1507CS8PBF | 制造商:Linear Technology 功能描述:LT1507CS8PBF |
| LT1507G | 制造商:DIODES 制造商全称:Diodes Incorporated 功能描述:1.5A GLASS PASSIVATED RECTIFIER |
| LT1507I | 制造商:LINER 制造商全称:Linear Technology 功能描述:500kHz Monolithic Buck Mode Switching Regulator |
| LT1507IN8 | 功能描述:IC REG BUCK ADJ 1.5A 8DIP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1507IN8#PBF | 功能描述:IC REG BUCK ADJ 1.5A 8DIP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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