- 您现在的位置：买卖IC网 > PDF目录15288 > LTC1929CG-PG (Linear Technology)IC REG CTRLR BUCK PWM CM 28-SSOP PDF资料下载
参数资料
| 型号： | LTC1929CG-PG |
| 厂商： | Linear Technology |
| 文件页数： | 10/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 28-SSOP |
| 标准包装： | 47 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 360kHz |
| 占空比： | 99.5% |
| 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 ~ 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
LTC1929/LTC1929-PG
OPERATIO
Main Control Loop
(Refer to Functional Diagram)
Low Current Operation
The LTC1929 uses a constant frequency, current mode
step-down architecture with inherent current sharing.
During normal operation, the top MOSFET is turned on
each cycle when the oscillator sets the RS latch, and
turned off when the main current comparator, I 1 , resets
the RS latch. The peak inductor current at which I 1 resets
the RS latch is controlled by the voltage on the I TH pin,
which is the output of the error amplifier EA. The differen-
tial amplifier, A1, produces a signal equal to the differential
voltage sensed across the output capacitor but re-refer-
ences it to the internal signal ground (SGND) reference.
The EAIN pin receives a portion of this voltage feedback
signal at the DIFFOUT pin which is compared to the
internal reference voltage by the EA. When the load current
increases, it causes a slight decrease in the EAIN pin
voltage relative to the 0.8V reference, which in turn causes
the I TH voltage to increase until the average inductor
current matches the new load current. After the top
MOSFET has turned off, the bottom MOSFET is turned on
for the rest of the period.
The top MOSFET drivers are biased from floating boot-
strap capacitor C B , which normally is recharged during
each off cycle through an external Schottky diode. When
V IN decreases to a voltage close to V OUT , however, the loop
may enter dropout and attempt to turn on the top MOSFET
continuously. A dropout detector detects this condition
and forces the top MOSFET to turn off for about 400ns
every 10th cycle to recharge the bootstrap capacitor.
The main control loop is shut down by pulling Pin 1 (RUN/
SS) 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, I TH is gradually re-
leased allowing normal operation to resume. When the
RUN/SS pin is low, all LTC1929 functions are shut down.
If V OUT has not reached 70% of its nominal value when C SS
has charged to 4.1V, an overcurrent latchoff can be
invoked as described in the Applications Information
section.
The LTC1929 operates in a continuous, PWM control
mode. The resulting operation at low output currents
optimizes transient response at the expense of substantial
negative inductor current during the latter part of the
period. The level of ripple current is determined by the
inductor value, input voltage, output voltage, and fre-
quency of operation.
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 140kHz to 310kHz 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 minimum frequency.
Input capacitance ESR requirements and efficiency losses
are substantially reduced because the peak current drawn
from the input capacitor is effectively divided by two and
power loss is proportional to the RMS current squared. A
two stage, single output voltage implementation can re-
duce input path power loss by 75% and radically reduce
the required RMS current rating of the input capacitor(s).
INTV CC /EXTV CC Power
Power for the top and bottom MOSFET drivers and most
of the IC circuitry is derived from INTV CC . When the
EXTV CC pin is left open, an internal 5V low dropout
regulator supplies INTV CC power. If the EXTV CC pin is
taken above 4.7V, the 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. An external Schottky
diode can be used to minimize the voltage drop from
EXTV CC to INTV CC in applications requiring greater than
the specified INTV CC current. Voltages up to 7V can be
applied to EXTV CC for additional gate drive capability.
10
相关PDF资料 |
PDF描述 |
|---|---|
| RLB9012-821KL | INDUCTOR HI CURRENT RADIAL 820UH |
| RLB9012-681KL | INDUCTOR HI CURRENT RADIAL 680UH |
| LTC3829EUHF#TRPBF | IC REG CTRLR BUCK PWM CM 38-QFN |
| GBM43DTMN | CONN EDGECARD 86POS R/A .156 SLD |
| RLB9012-561KL | INDUCTOR HI CURRENT RADIAL 560UH |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1929CG-PG#25123 | 制造商:Linear Technology 功能描述: |
| LTC1929CG-PG#25123#TR | 制造商:Linear Technology 功能描述: |
| LTC1929CG-PG#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:- 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 |
| LTC1929CG-PG#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:- 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 |
| LTC1929CG-PG#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:- 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。