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参数资料
| 型号： | LTC3827IG-1#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 10/32页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 2,000 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 580kHz |
| 占空比： | 99.4% |
| 电源电压： | 4 V ~ 36 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： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
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LTC3827-1
OPERATION (Refer to Functional Diagram)
INTV CC /EXTV CC Power
Power for the top and bottom MOSFET drivers and most
other internal circuitry is derived from the INTV CC pin.
When the EXTV CC pin is left open or tied to a voltage less
than 4.7V, an internal 5.25V low dropout linear regulator
supplies INTV CC power from V IN . If EXTV CC is taken above
4.7V, the 5.25V regulator is turned off and a 7.5V low
dropout linear regulator is enabled that supplies INTV CC
power from EXTV CC . If EXTV CC is less than 7.5V (but
greater than 4.7V), the 7.5V regulator is in dropout and
INTV CC is approximately equal to EXTV CC . When EXTV CC
is greater than 7.5V (up to an absolute maximum rating
of 10V), INTV CC is regulated to 7.5V. Using the EXTV CC
pin allows the INTV CC power to be derived from a high
ef?ciency external source such as one of the LTC3827-1
switching regulator outputs.
Each top MOSFET driver is biased from the ?oating boot-
strap capacitor C B , which normally recharges during each
off cycle through an external diode when the top MOSFET
turns off. If the input voltage V IN decreases to a voltage
close to V OUT , the loop may enter dropout and attempt
to turn on the top MOSFET continuously. The dropout
detector detects this and forces the top MOSFET off for
about one twelfth of the clock period every tenth cycle to
allow C B to recharge.
Shutdown and Start-Up (RUN1, RUN2 and
TRACK/SS1, TRACK/SS2 Pins)
The two channels of the LTC3827-1 can be independently
shut down using the RUN1 and RUN2 pins. Pulling either
of these pins below 0.7V shuts down the main control
loop for that controller. Pulling both pins low disables
both controllers and most internal circuits, including the
INTV CC regulator, and the LTC3827-1 draws only 8μA of
quiescent current.
Releasing either RUN pin allows an internal 0.5μA current
to pull up the pin and enable that controller. Alternatively,
the RUN pin may be externally pulled up or driven directly
by logic. Be careful not to exceed the Absolute Maximum
rating of 7V on this pin.
The start-up of each controller’s output voltage V OUT is con-
trolled by the voltage on the TRACK/SS1 and TRACK/SS2
pin. When the voltage on the TRACK/SS pin is less than
the 0.8V internal reference, the LTC3827-1 regulates the
V FB voltage to the TRACK/SS pin voltage instead of the
0.8V reference. This allows the TRACK/SS pin to be used
to program a soft-start by connecting an external capacitor
from the TRACK/SS pin to SGND. An internal 1μA pull-up
current charges this capacitor creating a voltage ramp on
the TRACK/SS pin. As the TRACK/SS voltage rises linearly
from 0V to 0.8V (and beyond), the output voltage V OUT
rises smoothly from zero to its ?nal value.
Alternatively the TRACK/SS pin can be used to cause the
startup of V OUT to “track” that of another supply. Typically,
this requires connecting to the TRACK/SS pin an external
resistor divider from the other supply to ground (see Ap-
plications Information section).
When the corresponding RUN pin is pulled low to disable
a controller, or when V IN drops below its undervoltage
lockout threshold of 3.5V, the TRACK/SS pin is pulled low
by an internal MOSFET. When in undervoltage lockout,
both controllers are disabled and the external MOSFETs
are held off.
Light Load Current Operation (Burst Mode Operation,
Pulse-Skipping or Continuous Conduction)
(PLLIN/MODE Pin)
The LTC3827-1 can be enabled to enter high ef?ciency
Burst Mode operation, constant frequency pulse-skipping
mode, or forced continuous conduction mode at low load
currents. To select Burst Mode operation, tie the PLLIN/
MODE pin to a DC voltage below 0.7V (e.g., SGND). To
select forced continuous operation, tie the PLLIN/MODE
pin to INTV CC . To select pulse-skipping mode, tie the
PLLIN/MODE pin to a DC voltage greater than 0.9V and
less than INTV CC – 1.2V.
When a controller is enabled for Burst Mode operation,
the peak current in the inductor is set to approximately
one-tenth of the maximum sense voltage even though the
voltage on the I TH pin indicates a lower value. If the aver-
age inductor current is lower than the load current, the
error ampli?er EA will decrease the voltage on the I TH pin.
38271fe
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相关代理商/技术参数 |
参数描述 |
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| LTC3827IUH#PBF | 功能描述:IC REG CTRLR BUCK 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: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 |
| LTC3827IUH#TRPBF | 功能描述:IC REG CTRLR BUCK 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: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 |
| LTC3828EG#PBF | 功能描述:IC REG CTRLR BUCK 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:PolyPhase® 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LTC3828EG#TRPBF | 功能描述:IC REG CTRLR BUCK 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: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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