- 您现在的位置：买卖IC网 > PDF目录15273 > LTC3731CG#TRPBF (Linear Technology)IC REG CTRLR BUCK PWM CM 36-SSOP PDF资料下载
参数资料
| 型号： | LTC3731CG#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 20/34页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 36-SSOP |
| 标准包装： | 2,000 |
| 系列： | PolyPhase® |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 750kHz |
| 占空比： | 98.5% |
| 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： | 0°C ~ 70°C |
| 封装/外壳： | 36-SSOP（0.209"，5.30mm 宽） |
| 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页第15页第16页第17页第18页第19页当前第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
LTC3731
APPLICATIONS INFORMATION
CALCULATE FOR
troubleshootingofthecircuitandPClayout.Theinternal
foldback current limiting still remains active, thereby pro-
tecting the power supply system from failure. A decision
can be made after the design is complete whether to rely
solely on foldback current limiting or to enable the latchoff
feature by removing the pull-up resistor.
The value of the soft-start capacitor C SS may need to be
scaled with output current, output capacitance and load
current characteristics. The minimum soft-start capaci-
tance is given by:
C SS > (C OUT )(V OUT ) (10 –4 ) (R SENSE )
The minimum recommended soft-start capacitor of
C SS = 0.1μF will be sufficient for most applications.
Current Foldback
In certain applications, it may be desirable to defeat the
internal current foldback function. A negative impedance
is experienced when powering a switching regulator. That
is, the input current is higher at a lower V IN and decreases
as V IN is increased. Current foldback is designed to ac-
commodate a normal, resistive load having increasing
current draw with increasing voltage. The EAIN pin should
be artificially held 70% above its nominal operating level
of 0.6V, or 0.42V in order to prevent the IC from “folding
back” the peak current level. A suggested circuit is shown
in Figure 8.
The emitter of Q1 will hold up the EAIN pin to a voltage in
the absence of V OUT that will prevent the internal sensing
circuitry from reducing the peak output current. Remov-
ing the function in this manner eliminates the external
MOSFET’s protective feature under short-circuit conditions.
This technique will also prevent the short-circuit latchoff
V CC V CC
LTC3731
Q1
EAIN
0.42V TO 0.55V
3731 F08
Figure 8. Foldback Current Elimination
function from turning off the part during a short-circuit
event and the peak output current will only be limited to
N ? 75mV/R SENSE .
Undervoltage Reset
In the event that the input power source to the IC (V CC )
drops below 4V, the RUN/SS capacitor will be discharged
to ground. When V CC rises above 4V, the RUN/SS capacitor
will be allowed to recharge and initiate another soft-start
turn-on attempt. This may be useful in applications that
switch between two supplies that are not diode connected,
but note that this cannot make up for the resultant inter-
ruption of the regulated output.
Phase-Locked Loop and Frequency Synchronization
The IC has a phase-locked loop comprised of an internal
voltage controlled oscillator and phase detector. This allows
the top MOSFET of output stage 1’s turn-on to be locked
to the rising edge of an external source. The frequency
range of the voltage controlled oscillator is ±50% around
the center frequency f O . A voltage applied to the PLLFLTR
pin of 1.2V corresponds to a frequency of approximately
400kHz. The nominal operating frequency range of the IC
is 225kHz to 680kHz.
The phase detector used is an edge sensitive digital type
that provides zero degrees phase shift between the external
and internal oscillators. This type of phase detector will
not lock the internal oscillator to harmonics of the input
frequency. The PLL hold-in range, ? f H , is equal to the
capture range, ? f C :
? f H = ? f C = ±0.5 f O
The output of the phase detector is a complementary pair
of current sources charging or discharging the external
filter components on the PLLFLTR pin. A simplified block
diagram is shown in Figure 9.
If the external frequency (f PLLIN ) is greater than the os-
cillator frequency, f OSC , current is sourced continuously,
pulling up the PLLFLTR pin. When the external frequency is
less than f OSC , current is sunk continuously, pulling down
the PLLFLTR pin. If the external and internal frequencies
are the same, but exhibit a phase difference, the current
sources turn on for an amount of time corresponding to
3731fc
20
相关PDF资料 |
PDF描述 |
|---|---|
| VI-J5J-EW-F4 | CONVERTER MOD DC/DC 36V 100W |
| VI-J5J-EW-F2 | CONVERTER MOD DC/DC 36V 100W |
| LTC3736EGN-1 | IC REG CTRLR BUCK PWM CM 24-SSOP |
| VI-J5J-EW-F1 | CONVERTER MOD DC/DC 36V 100W |
| VI-J54-EW-F4 | CONVERTER MOD DC/DC 48V 100W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3731CUH | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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 |
| LTC3731CUH#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 |
| LTC3731CUH#PBF | 制造商:Linear Technology 功能描述:DC-DC CONVERTER, BUCK, 600KHZ, 240A, QFN |
| LTC3731CUH#TR | 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN 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 |
| LTC3731CUH#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 |
发布紧急采购，3分钟左右您将得到回复。