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| 型号： | LTC1624CS8#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK INV 8SOIC |
| 标准包装： | 100 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 225kHz |
| 占空比： | 95% |
| 电源电压： | 3.5 V ~ 36 V |
| 降压： | 是 |
| 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： | 0°C ~ 70°C |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1333 (CN2011-ZH PDF) |
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LTC1624
APPLICATIO N S I N FOR M ATIO N
pin through a small Schottky diode (like a Central
CMDSH-3) to V OUT as shown in Figure 10. However, for
3.3V
OR 5V
D1
I TH /RUN
I TH /RUN
3.3V and other lower voltage regulators, additional cir-
cuitry is required to derive boost supply power from the
output.
For low input voltage operation (V IN < 7V), a Schottky
diode can be connected from V IN to BOOST to increase the
external MOSFET gate drive voltage. Be careful not to
exceed the maximum voltage on BOOST to SW pins
of 7.8V.
Output Voltage Programming
The output voltage is set by a resistive divider according
to the following formula:
(a)
C C
R C
R1
C1
D1
(b)
I TH /RUN
C C
R C
C C
R C
V OUT = 1 . 19 V ? 1 +
?
?
R 2 ?
R 1 ? ?
(c)
Figure 3. I TH / RUN Pin Interfacing
1624 F03
The external resistive divider is connected to the output as
shown in Figure 2, allowing remote voltage sensing. When
using remote sensing, a local 100 ? resistor should be
connected from L1 to R2 to prevent V OUT from running
away if the sense lead is disconnected.
Soft start can be implemented by ramping the voltage on
I TH /RUN during start-up as shown in Figure 3(c). As the
voltage on I TH/RUN ramps from 1.19V to 2.4V the internal
peak current limit is also ramped at a proportional linear
rate. The peak current limit begins at approximately
10mV/R SENSE (at V ITH/RUN = 1.4V) and ends at:
V FB
L1
R2
V OUT
160mV/R SENSE (V ITH/RUN = 2.4V)
The output current thus ramps up slowly, charging the
LTC1624
GND
100pF
R1
output capacitor. The peak inductor current and maximum
output current are as follows:
1624 F02
I L(PEAK) = (V ITH/RUN – 1.3V)/(6.8R SENSE )
Figure 2. Setting the LTC1624 Output Voltage
I TH /RUN Function
The I TH /RUN pin is a dual purpose pin that provides the
loop compensation and a means to shut down the LTC1624.
Soft start can also be implemented with this pin. Soft start
reduces surge currents from V IN by gradually increasing
the internal current limit. Power supply sequencing can
also be accomplished using this pin.
An internal 2.5 μ A current source charges up the external
capacitor C C. When the voltage on I TH /RUN reaches 0.8V
the LTC1624 begins operating. At this point the error
amplifier pulls up the I TH /RUN pin to its maximum of 2.4V
(assuming V OUT is starting low).
10
I OUT(MAX) = I LPEAK – ? I L / 2
with ? I L = ripple current in the inductor.
During normal operation the voltage on the I TH /RUN pin
will vary from 1.19V to 2.4V depending on the load current.
Pulling the I TH /RUN pin below 0.8V puts the LTC1624 into
a low quiescent current shutdown (I Q < 30 μ A). This pin can
be driven directly from logic as shown in Figures 3(a)
and 3(b).
Efficiency Considerations
The percent efficiency of a switching regulator is equal to
the output power divided by the input power times 100%.
It is often useful to analyze individual losses to determine
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相关代理商/技术参数 |
参数描述 |
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| LTC1624IS8 | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC 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 |
| LTC1624IS8#PBF | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC 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 |
| LTC1624IS8#PBF | 制造商:Linear Technology 功能描述:DC/DC Converter IC |
| LTC1624IS8#TR | 功能描述:IC REG CTRLR BST FLYBK INV 8SOIC 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 |
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