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参数资料
| 型号： | LTC3788IUH#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PQCC32 |
| 封装： | 5 X 5 MM, LEAD FREE, PLASTIC, MO-220WHHD, QFN-32 |
| 文件页数： | 11/32页 |
| 文件大小： | 386K |
| 代理商： | LTC3788IUH#PBF |
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LTC3788
19
3788fb
applicaTions inForMaTion
The LTC3788 can also be configured as a 2-phase single
output converter where the outputs of the two channels
are connected together and both channels have the same
duty cycle. With 2-phase operation, the two channels of
thedualswitchingregulatorareoperated180degreesout-
of-phase. This effectively interleaves the output capacitor
currentpulses,greatlyreducingtheoutputcapacitorripple
current. As a result, the ESR requirement of the capacitor
can be relaxed. Because the ripple current in the output
capacitorisasquarewave,theripplecurrentrequirements
fortheoutputcapacitordependonthedutycycle,thenum-
ber of phases and the maximum output current. Figure 3
illustrates the normalized output capacitor ripple current
as a function of duty cycle in a 2-phase configuration. To
choose a ripple current rating for the output capacitor,
first establish the duty cycle range based on the output
voltage and range of input voltage. Referring to Figure 3,
choose the worst-case high normalized ripple current as
a percentage of the maximum load current.
Multiple capacitors placed in parallel may be needed to
meet the ESR and RMS current handling requirements.
Dry tantalum, special polymer, aluminum electrolytic and
ceramic capacitors are all available in surface mount
packages. Ceramic capacitors have excellent low ESR
characteristics but can have a high voltage coefficient.
Capacitors are now available with low ESR and high ripple
current ratings (i.e., OS-CON and POSCAP).
Setting Output Voltage
The LTC3788 output voltages are each set by an external
feedback resistor divider carefully placed across the out-
put, as shown in Figure 4. The regulated output voltage
is determined by:
VOUT = 1.2V 1+
RB
RA
Great care should be taken to route the VFB line away
from noise sources, such as the inductor or the SW line.
Figure 3. Normalized Output Capacitor Ripple
Current (RMS) for a Boost Converter
0.1
I ORIPPLE
/I
OUT
0.9
3788 F03
0.3
0.5
0.7 0.8
0.2
0.4
0.6
3.25
3.00
2.75
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
DUTY CYCLE OR (1-VIN/VOUT)
1-PHASE
2-PHASE
Figure 4. Setting Output Voltage
LTC3788
VFB
VOUT
RB
RA
3788 F04
Figure 5. Using the SS Pin to Program Soft-Start
LTC3788
SS
CSS
SGND
3788 F05
Soft-Start (SS Pins)
The start-up of each VOUT is controlled by the voltage
on the respective SS pins. When the voltage on the SS
pin is less than the internal 1.2V reference, the LTC3788
regulates the VFB pin voltage to the voltage on the SS pin
instead of 1.2V.
Soft-startisenabledbysimplyconnectingacapacitorfrom
the SS pin to ground, as shown in Figure 5. An internal
10A current source charges the capacitor, providing a
linear ramping voltage at the SS pin. The LTC3788 will
regulate the VFB pin (and hence, VOUT) according to the
voltage on the SS pin, allowing VOUT to rise smoothly
from VIN to its final regulated value. The total soft-start
time will be approximately:
tSS = CSS
1.2V
10A
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| LTC3788IGN-1#PBF | DUAL SWITCHING CONTROLLER, 900 kHz SWITCHING FREQ-MAX, PDSO28 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3789EGN#PBF | 功能描述:IC REG CTRLR BST 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 |
| LTC3789EGN#PBF | 制造商:Linear Technology 功能描述:IC DC-DC CONV 600kHz SSOP28 |
| LTC3789EGN#TRPBF | 功能描述:IC REG CTRLR BST 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 |
| LTC3789EUFD#PBF | 功能描述:IC REG CTRLR BST PWM CM 28-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 |
| LTC3789EUFD#TRPBF | 功能描述:IC REG CTRLR BST PWM CM 28-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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