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参数资料
| 型号： | LTC3780IG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 13/30页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 24-SSOP |
| 标准包装： | 1,800 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 440kHz |
| 占空比： | 99% |
| 电源电压： | 4 V ~ 36 V |
| 降压： | 是 |
| 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-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
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LTC3780
OPERATION
MAIN CONTROL LOOP
V IN
V OUT
SW2
SW1
BOOST REGION
FOUR SWITCH PWM
BUCK/BOOST REGION
BUCK REGION
The LTC3780 is a current mode controller that provides an
output voltage above, equal to or below the input voltage.
The LTC proprietary topology and control architecture em-
ploys a current-sensing resistor in buck or boost modes.
The sensed inductor current is controlled by the voltage
on the I TH pin, which is the output of the amplifier EA. The
V OSENSE pin receives the voltage feedback signal, which
is compared to the internal reference voltage by the EA.
The top MOSFET drivers are biased from floating boost-
strap capacitors C A and C B (Figure 11), which are normally
recharged through an external diode when the top MOSFET
is turned off. Schottky diodes across the synchronous
switch D and synchronous switch B are not required, but
provide a lower drop during the dead time. The addition of
the Schottky diodes will typically improve peak efficiency
by 1% to 2% at 400kHz.
The main control loop is shut down by pulling the RUN
pin low. When the RUN pin voltage is higher than 1.5V, an
internal 1.2μA current source charges soft-start capacitor
C SS at the SS pin. The I TH voltage is then clamped to the
SS voltage while C SS is slowly charged during start-up.
This “soft-start” clamping prevents abrupt current from
being drawn from the input power supply.
POWER SWITCH CONTROL
Figure 1 shows a simplified diagram of how the four
power switches are connected to the inductor, V IN , V OUT
and GND. Figure 2 shows the regions of operation for the
LTC3780 as a function of duty cycle D. The power switches
are properly controlled so the transfer between modes is
continuous. When V IN approaches V OUT , the buck-boost
region is reached; the mode-to-mode transition time is
typically 200ns.
Buck Region (V IN > V OUT )
Switch D is always on and switch C is always off during
this mode. At the start of every cycle, synchronous switch
B is turned on first. Inductor current is sensed when
synchronous switch B is turned on. After the sensed in-
ductor current falls below the reference voltage, which is
proportional to V ITH , synchronous switch B is turned off
TG2 A D TG1
L
BG2 B C BG1
R SENSE
3780 F01
Figure 1. Simplified Diagram of the Output Switches
98%
D MAX
BOOST
A ON, B OFF
PWM C, D SWITCHES
D MIN
BOOST
D MAX
BUCK
D ON, C OFF
PWM A, B SWITCHES
3%
D MIN 3780 F02
BUCK
Figure 2. Operating Mode vs Duty Cycle
and switch A is turned on for the remainder of the cycle.
switches A and B will alternate, behaving like a typical
synchronous buck regulator. The duty cycle of switch A
increases until the maximum duty cycle of the converter
in buck mode reaches D MAX_BUCK , given by:
D MAX_BUCK = 100% – D BUCK-BOOST
where D BUCK-BOOST = duty cycle of the buck-boost switch
range:
D BUCK-BOOST = (200ns ? f) ? 100%
and f is the operating frequency in Hz.
Figure 3 shows typical buck mode waveforms. If V IN
approaches V OUT , the buck-boost region is reached.
Buck-Boost (V IN @ V OUT )
When V IN is close to V OUT , the controller is in buck-boost
mode. Figure 4 shows typical waveforms in this mode.
Every cycle, if the controller starts with switches B and D
turned on, switches A and C are then turned on. Finally,
switches A and D are turned on for the remainder of the
time. If the controller starts with switches A and C turned
3780ff
For more information www.linear.com/LTC3780
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3780IUH | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP |
| LTC3780IUH#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:- 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 |
| LTC3780IUH#PBF | 制造商:Linear Technology 功能描述:DC/DC Controller IC |
| LTC3780IUH#TR | 制造商:Linear Technology 功能描述:DC DC Cntrlr Dual-OUT Synchronous Boost/Buck Controller 4V to 36V Input 32-Pin QFN EP T/R |
| LTC3780IUH#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 |
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