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参数资料
| 型号： | LTC3788EUH#TRPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封装： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD, QFN-32 |
| 文件页数： | 4/32页 |
| 文件大小： | 386K |
| 代理商： | LTC3788EUH#TRPBF |
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LTC3788
12
3788fb
operaTion
Main Control Loop
The LTC3788 uses a constant-frequency, current mode
step-up architecture with the two controller channels op-
erating 180 or 240 degrees out-of-phase (depending on
the PHASMD pin connection). During normal operation,
each external bottom MOSFET is turned on when the clock
for that channel sets the RS latch, and is turned off when
the main current comparator, ICMP, resets the RS latch.
The peak inductor current at which ICMP trips and resets
the latch is controlled by the voltage on the ITH pin, which
is the output of the error amplifier EA. The error amplifier
compares the output voltage feedback signal at the VFB
pin, (which is generated with an external resistor divider
connected across the output voltage, VOUT, to ground) to
the internal 1.200V reference voltage. When the load cur-
rent increases, it causes a slight decrease in VFB relative
to the reference, which causes the EA to increase the ITH
voltage until the average inductor current matches the
new load current.
After the bottom MOSFET is turned off each cycle, the
top MOSFET is turned on until either the inductor current
starts to reverse, as indicated by the current comparator
IR, or the beginning of the next clock cycle.
INTVCC/EXTVCC Power
Power for the top and bottom MOSFET drivers and most
other internal circuitry is derived from the INTVCC pin.
When the EXTVCC pin is left open or tied to a voltage less
than 4.8V, the VBIAS LDO (low dropout linear regulator)
supplies 5.4V from VBIAS to INTVCC. If EXTVCC is taken
above 4.8V, the VBIAS LDO is turned off and an EXTVCC
LDO is turned on. Once enabled, the EXTVCC LDO supplies
5.4V from EXTVCC to INTVCC. Using the EXTVCC pin allows
the INTVCC power to be derived from a high efficiency
external source such as one of the LTC3788 switching
regulator outputs.
Shutdown and Start-Up
(RUN1, RUN2 and SS1, SS2 Pins)
The two channels of the LTC3788 can be independently
shutdownusingtheRUN1andRUN2pins.Pullingeitherof
these pins below 1.28V shuts down the main control loop
for that controller. Pulling both pins below 0.7V disables
both controllers and most internal circuits, including the
INTVCC LDOs. In this state, the LTC3788 draws only 8A
of quiescent current.
The RUN pin may be externally pulled up or driven directly
by logic. When driving the RUN pin with a low impedance
source, do not exceed the absolute maximum rating of
8V. The RUN pin has an internal 11V voltage clamp that
allows the RUN pin to be connected through a resistor to a
higher voltage (for example, VIN),aslongasthemaximum
current into the RUN pin does not exceed 100A.
The start-up of each controller’s output voltage VOUT is
controlled by the voltage on the SS pin for that channel.
When the voltage on the SS pin is less than the 1.2V
internal reference, the LTC3788 regulates the VFB voltage
to the SS pin voltage instead of the 1.2V reference. This
allows the SS pin to be used to program a soft-start by
connecting an external capacitor from the SS pin to SGND.
An internal 10A pull-up current charges this capacitor
creating a voltage ramp on the SS pin. As the SS voltage
rises linearly from 0V to 1.2V (and beyond up to INTVCC),
the output voltage VOUT rises smoothly to its final value.
Light Load Current Operation—Burst Mode Operation,
Pulse-Skipping or Continuous Conduction
(PLLIN/MODE Pin)
The LTC3788 can be enabled to enter high efficiency Burst
Modeoperation,constant-frequencypulse-skippingmode
orforcedcontinuousconductionmodeatlowloadcurrents.
To select Burst Mode operation, tie the PLLIN/ MODE pin
to a ground (e.g., SGND). To select forced continuous
operation, tie the PLLIN/MODE pin to INTVCC. To select
pulse-skipping mode, tie the PLLIN/MODE pin to a DC
voltage greater than 1.2V and less than INTVCC – 1.3V.
When a controller is enabled for Burst Mode operation, the
minimum peak current in the inductor is set to approxi-
mately 30% of the maximum sense voltage even though
the voltage on the ITH pin indicates a lower value. 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 0.425V, the internal
sleep signal goes high (enabling sleep mode) and both
external MOSFETs are turned off.
(Refer to Block Diagram)
相关PDF资料 |
PDF描述 |
|---|---|
| LTC3788EUH#PBF | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3788IUH#PBF | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC32 |
| LTC3788IGN-1#PBF | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO28 |
| LTC3788EGN-1#TRPBF | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO28 |
| LTC3789EGN#TRPBF | 0.1 A SWITCHING CONTROLLER, 710 kHz SWITCHING FREQ-MAX, PDSO28 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3788IGN-1#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP 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 |
| LTC3788IGN-1#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP 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 |
| LTC3788IUH#PBF | 功能描述:IC REG CTRLR BST PWM CM 32-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: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 |
| LTC3788IUH#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 32-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: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 |
| LTC3789EGN#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-SSOP 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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