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参数资料
| 型号： | LTC3829EUHF#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PQCC38 |
| 封装： | 5 X 7 MM, LEAD FREE, PLASTIC, M0-220WHKD, QFN-38 |
| 文件页数： | 5/40页 |
| 文件大小： | 478K |
| 代理商： | LTC3829EUHF#PBF |
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LTC3829
3829f
Light Load Current Operation (Burst Mode Operation,
Stage Shedding or Continuous Conduction)
The LTC3829 can be enabled to enter high efficiency
Burst Mode operation, Stage Shedding mode or forced
continuous conduction mode. To select forced continuous
operation, tie the MODE pin to a DC voltage below 0.6V
(e.g., SGND). To select Stage Shedding mode of opera-
tion, tie the MODE pin to INTVCC. To select Burst Mode
operation, float the MODE pin.
When the controller is enabled for Burst Mode operation,
the peak current in the inductor is set to approximately
one-sixth of the maximum sense voltage even though the
voltage on the ITH pin indicates a lower value. The peak
current can be programmed through the ISET pin. If the
average inductor current is higher than the load current,
the error amplifier, EA, will decrease the voltage on the
ITH pin. When the ITH voltage drops below 0.5V (can
also be programmed by the ISET pin), the internal sleep
signal goes high (enabling sleep mode) and the external
MOSFETs are turned off. In sleep mode, the load current
is supplied by the output capacitor. As the output voltage
decreases, the EA’s output begins to rise. When the output
voltage drops enough, the sleep signal goes low, and the
controller resumes normal operation by turning on the top
externalMOSFETonthenextcycleoftheinternaloscillator.
When a controller is enabled for Burst Mode operation,
the inductor current is not allowed to reverse. The reverse
current comparator, IREV, turns off the bottom external
MOSFET just before the inductor current reaches zero,
preventing it from reversing and going negative. Thus, the
controller operates in discontinuous operation. In forced
continuous operation, the inductor current is allowed to
reverse at light loads or under large transient conditions.
The peak inductor current is determined by the voltage
on the ITH pin. In this mode, the efficiency at light loads is
lower than in Burst Mode operation. However, continuous
mode has the advantages of lower output ripple and less
interference with audio circuitry.
When the MODE pin is connected to INTVCC,theLTC3829
operates in Stage Shedding mode at light loads. The
controller will turn off channels 2 and 3 and increase
the current gain of the first channel to ensure smooth
transition. The threshold where the controller goes into
Stage Shedding mode is when the ITH voltage drops
below 0.5V, but it can be programmed by ISET pin. The
inductor current is not allowed to reverse in this mode
(discontinuousoperation).Atverylightloads,thecurrent
comparator may remain tripped for several cycles and
force the external top MOSFET to stay off for the same
number of cycles (i.e., skipping pulses). This mode ex-
hibits low output ripple as well as low audio noise and
reduced RF interference as compared to Burst Mode
operation. It provides higher low current efficiency than
forced continuous mode, but not nearly as high as Burst
Mode operation.
2-Chip Operations (CLKOUT Pin)
The LTC3829’s three channels are 120° out of phase
providing multiphase operation. This configuration can
provide enough power for most high current applications.
However, for even higher power applications, the LTC3829
can be configured for PolyPhase and 2-chip operation.
The LTC3829 features a CLKOUT pin which enables two
LTC3829s to operate out of phase. The CLKOUT signal is
60°outofphasewithrespecttophase1ofthecontroller.In
StageSheddingmode,however,theCLKOUTsignalis180°
out of phase with respect to phase 1 of the controller.
Frequency Selection and Phase-Locked Loop
(FREQ and PLLIN Pins)
Theselectionofswitchingfrequencyisatrade-offbetween
efficiency and component size. Low frequency opera-
tion increases efficiency by reducing MOSFET switching
losses, but requires larger inductance and/or capacitance
to maintain low output ripple voltage.
If the PLLIN pin is not being driven by an external clock
source,theFREQpincanbeusedtoprogramthecontroller’s
operating frequency from 250kHz to 770kHz. There is a
precision 10A current flowing out of the FREQ pin so that
the user can program the controller’s switching frequency
with a single resistor to SGND. A curve is provided later in
theApplicationsInformationsectionshowingtherelation-
ship between the voltage on the FREQ pin and switching
frequency.
operaTion (Refer to Functional Diagram)
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相关代理商/技术参数 |
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| LTC3829IFE#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC3829IFE#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 38TSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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 |
| LTC3829IUHF#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:PolyPhase® 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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