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| 型号： | LTC3811EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 20/48页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 38-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 850kHz |
| 占空比： | 90% |
| 电源电压： | 4.5 V ~ 30 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 ~ 85°C |
| 封装/外壳： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3811
OPERATION
(Refer to the Functional Diagram)
INDIVIDUAL INTV CC AND DRV CC
PINS LOCALLY DECOUPLED
(DRV CC NOT SHOWN)
MASTER
LTC3811
ONLY PGOOD PIN FOR
MASTER CHANNEL
IS USED (FLOAT SLAVE
CHANNEL PGOOD PINS)
the amplitude of those for one regulator to be drawn from
the input capacitor. These large amplitude current pulses
increased the total RMS current ?owing from the input
capacitor, requiring the use of more expensive input ca-
V OUT+
V OUT–
MASTER
DIFFERENTIAL
AMPLIFIER
USED TO DRIVE
CHANNEL 1
ERROR
AMPLIFIER
SLAVE
CHANNEL
FB PINS ALL
CONNECTED
TO LOCAL
INTV CC PINS
TO DISABLE
ERROR
AMPLIFIERS
SLAVE
CHANNEL
COMP
PINS ALL
CONNECTED
TO MASTER
CHANNEL
COMP PIN
SGND BUS ISOLATED FROM
PGND AND INDEPENDENTLY
ROUTED TO NEGATIVE
INTV CC PGOOD1
FB2 PGOOD2
DIFF/IN +
DIFF/IN –
DIFF/OUT RUN1
FB1 RUN2
COMP1 SS/TRACK1
COMP2 SS/TRACK2
CLK OUT SGND
SLAVE
SYNC LTC3811
INTV CC PGOOD1
FB2 PGOOD2
FB1 RUN1
COMP1 RUN2
COMP2 SS/TRACK1
SS/TRACK2
CLK OUT SGND
SLAVE
SYNC LTC3811
INTV CC PGOOD1
FB2 PGOOD2
FB1 RUN1
COMP1 RUN2
COMP2 SS/TRACK1
SS/TRACK2
SGND
3811 F04
ON/OFF
CONTROL
ALL
SS/TRACK
PINS
CONNECTED
TOGETHER
ALL RUN
PINS
CONNECTED
TOGETHER
pacitors and increasing both EMI and losses in the input
capacitor.
With multiphase operation, the two channels of the dual-
switching regulator are operated 180 degrees out of phase.
This effectively interleaves the current pulses drawn by the
switches, greatly reducing the overlap time where they add
together. The result is a signi?cant reduction in total RMS
input current, which in turn allows less expensive input
capacitors to be used, reduces shielding requirements for
EMI and improves real world operating ef?ciency.
Figure 5 illustrates the bene?ts of multiphase operation.
Current ripple at the input is reduced by a factor of 1.41
(square root of 2), reducing the size and cost of the input
capacitor. In addition, since power losses are proportional
to I RMS2 , signi?cant ef?ciency improvements in the input
power path components (batteries, switches, protection
circuitry and PCB traces) can be achieved. Improvements
in both conducted and radiated EMI also directly accrue
as a result of the reduced RMS input current.
I L
5A/DIV
TERMINAL OF OUTPUT CAPACITOR
SW1
Figure 4. LTC3811 Error Ampli?er Con?guration
for Multiphase Operation
10V/DIV
SW2
10V/DIV
FB pin of a slave phase to INTV CC . As shown in the Func-
tional Diagram, a comparator detects when the FB pin is
shorted to INTV CC and three-states this ampli?er’s output
V IN = 12V
V OUT = 1.5V
I OUT = 16A
1μs/DIV
3811 G41
and input. The COMP pins for all of the phases can then
be shorted together in order to provide compensation for
the feedback loop, as shown in Figure 4.
Theory and Bene?ts of Multiphase Operation
Why the need for multiphase operation? Up until the
multiphase family, constant frequency dual switching
regulators operated both channels in phase (i.e., single-
phase operation). This means that both switches turned
on at the same time, causing current pulses of up to twice
Figure 5. 2-Phase, Single Output Current Sharing Waveforms
Of course, the improvement afforded by 2-phase opera-
tion is a function of the dual switching regulator’s relative
duty cycles which, in turn, are dependent upon the input
voltage V IN (Duty Cycle = V OUT /V IN ).
Figure 6 shows the net ripple current seen by the output
capacitors for the different phase con?gurations. The
output ripple current is plotted for a ?xed output voltage
as the duty factor is varied between 10% and 90% on the
3811f
20
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相关代理商/技术参数 |
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| LTC3812EFE5#PBF | 制造商:Linear Technology 功能描述: |
| LTC3812EFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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 |
| LTC3812EFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
| LTC3812IFE-5#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16TSSOP 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) |
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