- 您现在的位置：买卖IC网 > PDF目录15252 > LTC3859EUHF#TRPBF (Linear Technology)IC REG CTRLR BST PWM CM 38-QFN PDF资料下载
参数资料
| 型号： | LTC3859EUHF#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/42页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST PWM CM 38-QFN |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式，Burst Mode? |
| 输出数： | 3 |
| 频率 - 最大： | 850kHz |
| 占空比： | 100% |
| 电源电压： | 4.5 V ~ 38 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： | 38-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页当前第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页第37页第38页第39页第40页第41页第42页
LTC3859
OPERATION
Main Control Loop
(Refer to Functional Diagram)
Each top MOSFET driver is biased from the ?oating
The LTC3859 uses a constant frequency, current mode
step-down architecture. The two buck controllers, chan-
nels 1 and 2, operate 180 degrees out of phase with each
other. The boost controller, channel 3, operates in phase
with channel 1. During normal operation, the external
top MOSFET for the buck channels (the external bottom
MOSFET for the boost channel) 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 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 for the
bucks (1.2V reference voltage for the boost). When the
load current 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 for the bucks (the bottom MOSFET
for the boost) is turned off each cycle, the bottom MOSFET
is turned on (the top MOSFET for the boost) 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, the V BIAS LDO (low dropout linear regulator)
supplies 5.4V from V BIAS to INTV CC . If EXTV CC is taken
above 4.7V, the V BIAS LDO is turned off and an EXTV CC
LDO is turned on. Once enabled, the EXTV CC LDO supplies
5.4V from EXTV CC to INTV CC . 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 LTC3859 switching
regulator outputs.
bootstrap capacitor C B , which normally recharges during
each cycle through an external diode when the switch
voltage goes low.
For buck channels 1 and 2, if the buck’s input voltage
decreases to a voltage close to its output, 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, RUN3 and
TRACK/SS1, TRACK/SS2, SS3 Pins)
The three channels of the LTC3859 can be independently
shut down using the RUN1, RUN2 and RUN3 pins. Pulling
any of these pins below 1.19V shuts down the main control
loop for that channel. Pulling all three pins below 0.7V
disables all controllers and most internal circuits, including
the INTV CC LDOs. In this state, the LTC3859 draws only
14μA of quiescent current.
Releasing a RUN pin allows a small internal current to pull
up the pin to enable that controller. The RUN1 pin has a
6μA pull-up current while the RUN2 and RUN3 pins have
a smaller 0.5μA. The 6μA current on RUN1 is designed
to be large enough so that the RUN1 pin can be safely
?oated (to always enable the controller) without worry
of condensation or other small board leakage pulling the
pin down. This is ideal for always-on applications where
one or more controllers are enabled continuously and
never shut down.
Each RUN pin may also be externally pulled up or driven
directly by logic. When driving a RUN pin with a low
impedance source, do not exceed the absolute maximum
rating of 8V. Each 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, V BIAS ), so
long as the maximum current in the RUN pin does not
exceed 100μA.
The start-up of each channel’s output voltage V OUT is
controlled by the voltage on the TRACK/SS pin (TRACK/SS1
for channel 1, TRACK/SS2 for channel 2, SS3 for channel 3).
When the voltage on the TRACK/SS pin is less than
3859fa
15
相关PDF资料 |
PDF描述 |
|---|---|
| H2AXT-10112-B8-ND | JUMPER-H1502TR/A3048B/X 12" |
| LTC1435IS#TRPBF | IC REG CTRLR BUCK PWM CM 16-SOIC |
| LTC1142CG#TR | IC REG CTRLR BUCK PWM CM 28-SSOP |
| H2AXT-10112-A8-ND | JUMPER-H1502TR/A3048A/X 12" |
| 9250A-823-RC | CHOKE RF MOLDED 82UH FERRITE |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3859IFE#PBF | 功能描述:IC REG CTRLR BST PWM CM 38-TSSOP 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 |
| LTC3859IFE#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 38-TSSOP 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 |
| LTC3859IUHF#PBF | 功能描述:IC REG CTRLR BST PWM CM 38VQFN 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: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) |
| LTC3859IUHF#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 38VQFN 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 |
| LTC3860EUH#PBF | 功能描述:IC REG CTRLR BUCK PWM VM 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® 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 |
发布紧急采购，3分钟左右您将得到回复。