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参数资料
| 型号： | LTC3852EUDD#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR DOUBLER PWM 24-QFN |
| 标准包装： | 73 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 810kHz |
| 占空比： | 99% |
| 电源电压： | 2.7 V ~ 38 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 是 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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LTC3852
APPLICATIONS INFORMATION
Regardless of the mode selected by the MODE/PLLIN pin,
the regulator will always start in pulse skipping mode up
to TRACK/SS = 0.64V. Between TRACK/SS = 0.64V and
0.72V, it will operate in forced continuous mode and revert
to the selected mode once TRACK/SS > 0.72V. The output
ripple is minimized during the 80mV forced continuous
mode window.
When the regulator is con?gured to track another supply,
the feedback voltage of the other supply is duplicated
by a resistor divider and applied to the TRACK/SS pin.
Therefore, the voltage ramp rate on this pin is determined
by the ramp rate of the other supply’s voltage. Note that
the small soft-start capacitor charging current is always
?owing, producing a small offset error. To minimize this
error, one can select the tracking resistive divider value to
be small enough to make this error negligible.
In order to track down another supply after the soft-start
So which mode should be programmed? While either
mode in Figure 5 satis?es most practical applications,
the coincident mode offers better output regulation. This
concept can be better understood with the help of Figure 6.
At the input stage of the LTC3852’s error ampli?er, two
common anode diodes are used to clamp the equivalent
reference voltage and an additional diode is used to match
the shifted common mode voltage. The top two current
sources are of the same amplitude. In the coincident
mode, the TRACK/SS voltage is substantially higher than
0.8V at steady-state and effectively turns off D1. D2 and
D3 will therefore conduct the same current and offer
tight matching between V FB and the internal precision
0.8V reference. In the ratiometric mode, however, TRACK/SS
equals 0.8V at steady-state. D1 will divert part of the bias
current to make V FB slightly lower than 0.8V.
V MASTER
phase expires, the LTC3852 must be con?gured for forced
continuous operation by connecting MODE/PLLIN to
INTV CC .
V OUT
Output Voltage Tracking
The LTC3852 allows the user to program how its output
ramps up and down by means of the TRACK/SS pins.
Through this pin, the output can be set up to either
TIME
3852 F04a
coincidentally or ratiometrically track with another supply’s
output, as shown in Figure 4. In the following discussions,
V MASTER refers to a master supply and V OUT refers to the
LTC3852’s output as a slave supply. To implement the
coincident tracking in Figure 4a, connect a resistor divider
to V MASTER and connect its midpoint to the TRACK/SS pin
of the LTC3852. The ratio of this divider should be selected
the same as that of the LTC3852’s feedback divider as
shown in Figure 5a. In this tracking mode, V MASTER must
be higher than V OUT . To implement ratiometric tracking,
the ratio of the resistor divider connected to V MASTER is
determined by:
(4a) Coincident Tracking
V MASTER
V OUT
V OUT
V MASTER
=
R2 ? R3 + R4 ?
R4 ? ? R1 + R2 ? ?
TIME 3852 F04b
(4b) Ratiometric Tracking
Figure 4. Two Different Modes of Output Voltage Tracking
3852f
18
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相关代理商/技术参数 |
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| LTC3852IUDD#PBF | 功能描述:IC REG CTRLR DOUBLER PWM 24-QFN 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3852IUDD#TRPBF | 功能描述:IC REG CTRLR DOUBLER PWM 24-QFN 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:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3853EUJ#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC3853EUJ#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 40-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC3853EUJPBF | 制造商:Linear Technology 功能描述:DC-DC Controller Triple Buck 24V QFN40 |
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