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| 型号： | LTC3810EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/38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： | 1MHz |
| 占空比： | 93% |
| 电源电压： | 6.2 V ~ 100 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： | 28-SSOP（0.209"，5.30mm 宽） |
| 包装： | 管件 |
| 产品目录页面： | 1336 (CN2011-ZH PDF) |
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LTC3810
APPLICATIONS INFORMATION
application. A good starting point is to feed about 25%
of the voltage change at the I TH pin to the V ON pin as
shown in Figure 8. Place capacitance on the V ON pin to
?lter out the I TH variations at the switching frequency.
Inductor Selection
Given the desired input and output voltages, the induc-
tor value and operating frequency determine the ripple
current:
INTV CC
10V
R VON1
200k
R VON2
30k
C VON
0.01μF
100k
V ON
LTC3810
I L =
V OUT
fL
1
V OUT
V IN
I TH
3810 F08
Figure 8. Correcting Frequency Shift with Load Current Changes
Minimum Off-Time and Dropout Operation
The minimum off-time, t OFF(MIN) , is the smallest amount
of time that the LTC3810 is capable of turning on the bot-
tom MOSFET, tripping the current comparator and turning
the MOSFET back off. This time is generally about 250ns.
The minimum off-time limit imposes a maximum duty
cycle of t ON /(t ON + t OFF(MIN) ). If the maximum duty cycle
Lower ripple current reduces core losses in the inductor,
ESR losses in the output capacitors and output voltage
ripple. Highest ef?ciency operation is obtained at low
frequency with small ripple current. However, achieving
this requires a large inductor. There is a tradeoff between
component size, ef?ciency and operating frequency.
A reasonable starting point is to choose a ripple current
that is about 40% of I OUT(MAX) . The largest ripple current
occurs at the highest V IN . To guarantee that ripple current
does not exceed a speci?ed maximum, the inductance
should be chosen according to:
is reached, due to a dropping input voltage for example,
then the output will drop out of regulation. The minimum
input voltage to avoid dropout is:
L =
V OUT
f I L(MAX)
1
V OUT
V IN(MAX)
V IN(MIN) = V OUT
t ON + t OFF(MIN)
t ON
Once the value for L is known, the type of inductor must
be selected. High ef?ciency converters generally cannot
afford the core loss found in low cost powdered iron cores,
A plot of maximum duty cycle vs frequency is shown in
Figure 9.
2.0
forcing the use of more expensive ferrite, molypermalloy
or Kool Mμ ? cores. A variety of inductors designed for
high current, low voltage applications are available from
manufacturers such as Sumida, Panasonic, Coiltronics,
Coilcraft and Toko.
1.5
1.0
0.5
DROPOUT
REGION
Schottky Diode D1 Selection
The Schottky diode D1 shown in the front page schematic
conducts during the dead time between the conduction of
the power MOSFET switches. It is intended to prevent the
body diode of the bottom MOSFET from turning on and
0
0
0.25 0.50 0.75
DUTY CYCLE (V OUT /V IN )
1.0
3810 F09
storing charge during the dead time, which can cause a
modest (about 1%) ef?ciency loss. The diode can be rated
for about one half to one ?fth of the full load current since
Figure 9. Maximum Switching Frequency vs Duty Cycle
it is on for only a fraction of the duty cycle. In order for the
3810fc
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3810EUH-5#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:- 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 |
| LTC3810EUH-5#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:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 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:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| LTC3810HUH-5#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:- 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 |
| LTC3810HUH-5#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:- 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 |
| LTC3810IG | 制造商:Linear Technology 功能描述: |
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