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参数资料
| 型号： | LTC1148CS |
| 厂商： | Linear Technology |
| 文件页数： | 13/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 14-SOIC |
| 标准包装： | 55 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 250kHz |
| 占空比： | 100% |
| 电源电压： | 3.5 V ~ 18 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： | 0°C ~ 70°C |
| 封装/外壳： | 14-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
LTC1148
LTC1148-3.3/LTC1148-5
APPLICATIO S I FOR ATIO
and δ P = δ N = 0.007(63 – 25) = 0.27. The required R DS(ON)
for each MOSFET can now be calculated:
To prevent stray pickup a 100pF capacitor is suggested
across R1 located close to the LTC1148.
P-Ch R DS(ON) =
N-Ch R DS(ON) =
12(0.25)
5(2) 2 (1.27)
12(0.25)
7(2) 2 (1.27)
= 0.12 ?
= 0.085 ?
For Figure 1 applications with V OUT below 2V, or when
R SENSE is moved to ground, the current sense comparator
inputs operate near ground. When the current comparator
is operated at less than 2V common mode, the off time
increases approximately 40%, requiring the use of a
smaller timing capacitor C T .
The P-channel requirement can be met by a Si9430DY,
while the N-channel requirement is exceeded by a
Si9410DY. Note that the most stringent requirement for
the N-channel MOSFET is with V OUT = 0 (i.e., short circuit).
During a continuous short circuit, the worst-case
N-channel dissipation rises to:
P N = I SC(AVG)2 (R DS(ON) )(1 + δ N )
With the 0.05 ? sense resistor I SC(AVG) = 2A will result,
increasing the 0.085 ? N-channel dissipation to 450mW at
a die temperature of 73 ° C.
C IN will require an RMS current rating of at least 1A at
temperature, and C OUT will require an ESR of 0.05 ? for
optimum efficiency.
Now allow V IN to drop to its minimum value. At lower input
voltages the operating frequency will decrease and the
P-channel will be conducting most of the time, causing its
power dissipation to increase. At V IN(MIN) = 7V:
f MIN = (1/2.92 μ s)[1 – (5V/7V)] = 98kHz
Auxiliary Windings – Suppressing Burst Mode
Operation
The LTC1148 synchronous switch removes the normal
limitation that power must be drawn from the inductor
primary winding in order to extract power from auxil-
iary windings. With synchronous switching, auxiliary
outputs may be loaded without regard to the primary
output load, providing that the loop remains in continu-
ous mode operation.
Burst Mode operation can be suppressed at low output
currents with a simple external network which cancels the
25mV minimum current comparator threshold. This tech-
nique is also useful for eliminating audible noise from
certain types of inductors in high current (I OUT > 5A)
applications when they are lightly loaded.
An external offset is put in series with the SENSE – pin to
subtract from the built-in 25mV offset. An example of this
technique is shown in Figure 6. Two 100 ? resistors are
inserted in series with the leads from the sense resistor.
P P =
5V(0.12 ? )(2A) 2 (1.27)
7V
= 435mW
SENSE + (PIN 8)
R2
100 ?
This last step is necessary to assure that the power
dissipation and junction temperature of the P-channel are
SENSE – (PIN 7)
1000pF
R1
100 ?
R SENSE
not exceeded.
LTC1148 Adjustable Applications
R3
+
V OUT
C OUT
LTC1148 ? F06
When an output voltage other than 3.3V or 5V is required,
the LTC1148 adjustable version is used with an external
resistive divider from V OUT to V FB Pin 9 (see Figure 9). The
regulated voltage is determined by:
Figure 6. Suppression of Burst Mode Operation
)
V OUT = 1.25 1 + R2
R1
)
114835fd
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1148CS#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 14-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC1148CS#TR | 功能描述:IC REG CTRLR BUCK PWM CM 14-SOIC 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 |
| LTC1148CS#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 14-SOIC 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 |
| LTC1148CS-3.3 | 功能描述:IC REG CTRLR BUCK PWM CM 14-SOIC 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 |
| LTC1148CS-3.3#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 14-SOIC 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 |
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