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参数资料
| 型号： | LTC3826IUH#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 32-QFN |
| 标准包装： | 2,500 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 585kHz |
| 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： | 32-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
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LTC3826
OPERATION
Main Control Loop
(Refer to Functional Diagram)
Each top MOSFET driver is biased from the ?oating boot-
The LTC3826 uses a constant frequency, current mode
step-down architecture with the two controller channels
operating 180 degrees out of phase. During normal opera-
tion, each external top MOSFET is turned on when the clock
for that channel sets the RS latch, and is turned off when
the main current comparator, I CMP , resets the RS latch.
The peak inductor current at which I CMP trips and resets
the latch is controlled by the voltage on the I TH pin, which
is the output of the error ampli?er EA. The error ampli?er
compares the output voltage feedback signal at the V FB
pin, (which is generated with an external resistor divider
connected across the output voltage, V OUT , to ground) to
the internal 0.800V reference voltage. When the load cur-
rent increases, it causes a slight decrease in V FB relative
to the reference, which causes the EA to increase the I TH
voltage until the average inductor current matches the
new load current.
After the top MOSFET is turned off each cycle, the bottom
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.
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 LTC3826
switching regulator outputs.
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 LTC3826 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 LTC3826 draws only 4μA 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
controlled 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 LTC3826 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
start-up of V OUT to “track” that of another supply. Typi-
cally, this requires connecting to the TRACK/SS pin an
3826fc
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| LTC3827EG-1 | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Sync Step Down 4V to 36V Input 28-Pin SSOP |
| LTC3827EG-1#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) |
| LTC3827EG-1#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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