参数资料
| 型号： | LT1683EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 19/26页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM CM 20-SSOP |
| 标准包装： | 66 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 250kHz |
| 占空比： | 46% |
| 电源电压： | 4 V ~ 20 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 是 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 20-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1328 (CN2011-ZH PDF) |
LT1683
APPLICATIONS INFORMATION
I L(MAX) = 2A +
= 2.52A
N =
=
?I MAG =
= 81mA
? 4.1mH ? 100kHz
?I L = 2 ?
= 1A
DC NOM =
(
)
=
= 35.3%
? 47.5
I SW(PEAK) =
? 2.51A + 81mA = 494mA
?I SW(MAX) =
+ 81mA = 0.25A
L = ( 5 + 0.5 ) ? ( 1 ? 2 ? 35.3% ) = 16μH
?I L = ( 5 + 0.5 ) ? ( 1 ? 2 ? 29.1% ) = 1.03A
So, given the turns ratio, primary inductance and cur-
rent, the transformer can be designed. The design of the
transformer will require analyzing the power losses of the
transformer and making necessary adjustments.
Most transformer companies can assist you with designing
an optimal solution. For instance Midcom, Inc. (1-800-
643-2661). Linear Technology’s application group can
also help.
As an example say we are designing a 48V ±20% to 5V
100kHz converter with 2A output and 500mA ripple. Then
starting with a guess for the on voltage of the MOSFET
plus sense resistor of 0.5V and V F of 0.5V:
5 + 0.5 1
88% ? ( 48 ? 80% ? 0.5 ) 6.1
For continuous operation at I OUT(MIN) = I OUT(MAX) /4,
inductor ripple (the same as output ripple):
2A
4
The duty cycle for nominal input is:
V OUT + V F
2 ? N V IN(NOM) ? I SW ? R ON
5.5
2
6.1
Then:
1A ? 100kHz
Off-the-shelf components can be used for this inductor.
Say we choose a 22μH inductor, then ripple current at
maximum input (DC = 29.1%) is:
22μF ? 100kHz
The maximum inductor current is:
1.03A
2
Primary inductance should be greater than:
L PRI = 5 ? 22μH ? 6.1 2 = 4.1mH
The secondary inductance would then be:
4.1mH/6.1 2 = 110μH
The magnetizing ripple current is approximately:
5.5
1
6.1
Peak switch current is:
1
6.1
Note that you can discern your magnetizing ripple by
looking at the reflected inductance ripple and subtracting
it from the switch current ripple.
?I MAG = ?I SW – N ? I L
The max ripple current on the switch is:
1.03A
6.1
Knowing the peak switch current we can go back and
iterate with a more accurate switch-on voltage. We
would have to know the R ON of the FET. In our case our
assumptions of a 0.5V switch-on voltage is valid for
R ON + R SENSE < 1Ω.
Capacitors
Correct choice of input and output capacitors is very
important to low noise switcher performance. Push-pull
topologies and other low noise topologies will in general
have continuous currents, which reduce the requirements
1683fd
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1683IG | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1683IG#PBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1683IG#TR | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1683IG#TRPBF | 功能描述:IC REG CTRLR PWM CM 20-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 V 降压:是 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LT1684 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Ring Tone Generator |
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