- 您现在的位置：买卖IC网 > PDF目录15260 > LTC3727EG-1 (Linear Technology)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC3727EG-1 |
| 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： | 47 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 2 |
| 频率 - 最大： | 580kHz |
| 占空比： | 99% |
| 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： | 管件 |
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页当前第10页第11页第12页第13页第14页第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
LTC3727/LTC3727-1
OPERATIO
(Refer to Functional Diagram)
The top MOSFET drivers are biased from floating boot-
strap capacitor C B , which normally is recharged during
each off cycle through an external diode when the top
MOSFET turns off. As 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 de-
tects this and forces the top MOSFET off for about 400ns
every tenth cycle to allow C B to recharge.
The main control loop is shut down by pulling the RUN/SS
pin low. Releasing RUN/SS allows an internal 1.2 μ A
current source to charge soft-start capacitor C SS . When
C SS reaches 1.5V, the main control loop is enabled with the
I TH voltage clamped at approximately 30% of its maximum
value. As C SS continues to charge, the I TH pin voltage is
gradually released allowing normal, full-current opera-
tion. When both RUN/SS1 and RUN/SS2 are low, all
LTC3727/LTC3727-1 controller functions are shut down,
including the 7.5V and 3.3V regulators.
Low Current Operation
The FCB pin is a multifunction pin providing two func-
tions: 1) to provide regulation for a secondary winding by
temporarily forcing continuous PWM operation on
both controllers; and 2) to select between two modes of
low current operation. When the FCB pin voltage is below
0.8V, the controller forces continuous PWM current
mode operation. In this mode, the top and bottom
MOSFETs are alternately turned on to maintain the output
voltage independent of direction of inductor current.
When the FCB pin is below V INTVCC – 2V but greater than
0.8V, the controller enters Burst Mode operation. Burst
Mode operation sets a minimum output current level
before inhibiting the top switch and turns off the synchro-
nous MOSFET(s) when the inductor current goes nega-
tive. This combination of requirements will, at low cur-
rents, force the I TH pin below a voltage threshold that will
temporarily inhibit turn-on of both output MOSFETs until
the output voltage drops. There is 60mV of hysteresis in
the burst comparator B tied to the I TH pin. This hysteresis
produces output signals to the MOSFETs that turn them
on for several cycles, followed by a variable “sleep”
interval depending upon the load current. The resultant
output voltage ripple is held to a very small value by
having the hysteretic comparator follow the error ampli-
fier gain block.
Frequency Synchronization
The phase-locked loop allows the internal oscillator to be
synchronized to an external source via the PLLIN pin. The
output of the phase detector at the PLLFLTR pin is also the
DC frequency control input of the oscillator that operates
over a 250kHz to 550kHz range corresponding to a DC
voltage input from 0V to 2.4V. When locked, the PLL
aligns the turn on of the top MOSFET to the rising edge of
the synchronizing signal. When PLLIN is left open, the
PLLFLTR pin goes low, forcing the oscillator to its mini-
mum frequency.
Continuous Current (PWM) Operation
Tying the FCB pin to ground will force continuous current
operation. This is the least efficient operating mode, but
may be desirable in certain applications. The output can
source or sink current in this mode. When sinking current
while in forced continuous operation, current will be
forced back into the main power supply potentially boost-
ing the input supply to dangerous voltage levels—
BEWARE!
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, an internal 7.5V low
dropout linear regulator supplies INTV CC power. If EXTV CC
is taken above 7.3V, the 7.5V regulator is turned off and an
internal switch is turned on connecting EXTV CC to INTV CC .
This allows the INTV CC power to be derived from a high
efficiency external source such as the output of the regu-
lator itself or a secondary winding, as described in the
Applications Information section.
Output Overvoltage Protection
An overvoltage comparator, OV, guards against transient
overshoots (>7.5%) as well as other more serious condi-
tions that may overvoltage the output. In this case, the top
MOSFET is turned off and the bottom MOSFET is turned on
until the overvoltage condition is cleared.
3727fc
10
相关PDF资料 |
PDF描述 |
|---|---|
| ESA14DRMI-S288 | CONN EDGECARD 28POS .125 EXTEND |
| LTC3727EG#PBF | IC REG CTRLR BUCK PWM CM 28-SSOP |
| VE-27N-EY-F4 | CONVERTER MOD DC/DC 18.5V 50W |
| VE-2TN-EW-F3 | CONVERTER MOD DC/DC 18.5V 100W |
| VE-2TN-EW-F2 | CONVERTER MOD DC/DC 18.5V 100W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3727EG-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® 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 |
| LTC3727EG-1#TR | 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:否 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 |
| LTC3727EG-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 |
| LTC3727EG-1PBF | 制造商:Linear Technology 功能描述:DC-DC Controller Dual Step-Dn 36V SSOP28 |
| LTC3727EGPBF | 制造商:Linear Technology 功能描述:Dual Sync Buck Sw Vreg Controller SSOP28 |
发布紧急采购，3分钟左右您将得到回复。