参数资料
| 型号： | LT1683EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/26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
L
L PRI =
There are a number of ways to choose the inductance
value for L. We suggest as a starting point that L be selected
such that the converter is continuous at I OUT(MAX) /4. If your
minimum I OUT is higher than this or your components can
handle higher peak currents then use a higher number.
D1
1:N V OUT
C R OUT
V IN
L PRI
D2
The inductance of the transformer primary should be such
that L, when reflected into the primary, dominates the
input current. In other words, we want the magnetizing
current of the transformer small with respect to the current
going through the transformer to L. In general, then, the
inductance of the primary should be at least five times that
of L reflected to the input. This ensures that most of the
power will be passed through the transformer to the load.
It also increases the power capability of the converter and
reduces the peak currents that the switch will see.
5 ? L
N 2
R SENSE
Figure 7. Push-Pull Topology
1683 F07
If the magnetizing current is small, say below 100mA, then
a smaller L can be used with a higher percentage of the
switch current generated by the magnetizing current.
( V OUT + V F ) ? ( 1 ? 2 ? DC )
?I L =
I L(MAX) = I OUT(MAX) +
?I MAG = OUT
( V OUT(MIN) + V F ) ? ( 1 ? 2 ? DC )
Continuous operation occurs when the current in the
inductor never goes to zero. Discontinuous operation
occurs when the inductor current drops to zero before the
start of the next cycle and can occur with small inductors
and light loads. There is nothing inherently bad about
discontinuous operation, however, converter control and
operation are somewhat different. The inductor is smaller
for discontinuous operation but the peak currents in the
switch, the transformer, the diodes, inductor and capacitor
will be higher which may produce greater losses.
For continuous operation the inductor ripple current must
be less than twice the output current. The worst case for
this is at maximum input (lowest duty cycle, DC MIN ) but
in the following we will evaluate at nominal input since
the I OUT /4 is somewhat arbitrary.
Note when both inputs are off, the inductor current splits
between both secondary outputs and the diode common
goes to 0V.
Looking at the inductor current during off time, output
ripple current is:
?I OUT = 2 ? I OUT(MIN)
I OUT(MIN) = I OUT(MAX) / 4
L =
?I OUT ? f
With the value of L set, the ripple in the inductor is:
L ? f
However, the peak inductor current is evaluated at maxi-
mum load and maximum input voltage (minimum DC).
?I L(MAX)
2
The magnetizing ripple current can be shown to be:
V + V F
N ? L PRI ? f
and the peak current in the switch is:
I SW(PEAK) = N ? I L(MAX) + ?I MAG
This current should be less than the current limit.
Worst-case switch ripple is:
?I SW(PEAK) = N ? ?I L(MAX) + ?I MAG
In the push-pull converter the maximum switch voltage
will be 2 ? V IN . Because voltage is slew-controlled, the
leakage spikes are small. So, the MOSFET should have a
maximum rated switch voltage at least 20% higher than
2 ? V IN .
1683fd
18
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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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