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| 型号： | LTC3810EG#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 12/38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
OPERATION
Main Control Loop
The LTC3810 is a current mode controller for DC/DC step-
down converters. In normal operation, the top MOSFET
is turned on for a ?xed interval determined by a one-shot
timer (OST). When the top MOSFET is turned off, the bot-
tom MOSFET is turned on until the current comparator
I CMP trips, restarting the one-shot timer and initiating the
next cycle. Inductor current is determined by sensing the
voltage between the SENSE – and SENSE + pins using a
sense resistor or the bottom MOSFET on-resistance. The
voltage on the I TH pin sets the comparator threshold cor-
responding to the inductor valley current. The fast 25MHz
error ampli?er EA adjusts this voltage by comparing the
feedback signal V FB to the internal 0.8V reference volt-
age. If the load current increases, it causes a drop in the
feedback voltage relative to the reference. The I TH voltage
then rises until the average inductor current again matches
the load current.
The operating frequency is determined implicitly by the top
MOSFET on-time and the duty cycle required to maintain
regulation. The one-shot timer generates an on time that is
proportional to the ideal duty cycle, thus holding frequency
approximately constant with changes in V IN . The nominal
frequency can be adjusted with an external resistor R ON .
For applications with stringent constant frequency re-
quirements, the LTC3810 can be synchronized with an
external clock. By programming the nominal frequency
the same as the external clock frequency, the LTC3810
behaves as a constant frequency part against the load and
supply variations.
Pulling the SHDN pin low forces the controller into its
shutdown state, turning off both M1 and M2. Forcing a
voltage above 1.5V will turn on the device.
Pulse Skip Mode
The LTC3810 can operate in one of two modes selectable
with the MODE/SYNC pin—pulse skip mode or forced
continuous mode (see Figure 1). Pulse skip mode is se-
lected when increased ef?ciency at light loads is desired
(see Figure 2). In this mode, the bottom MOSFET is turned
off when inductor current reverses to minimize ef?ciency
loss due to reverse current ?ow and gate charge switching.
At low load currents, I TH will drop below the zero current
level (1.2V) shutting off both switches. Both switches will
remain off with the output capacitor supplying the load
current until the I TH voltage rises above the zero current
level to initiate another cycle. In this mode, frequency is
proportional to load current at light loads.
Pulse skip mode operation is disabled by comparator F
when the MODE/SYNC pin is brought below 0.8V, forcing
continuous synchronous operation. Forced continuous
mode is less ef?cient due to resistive losses, but has the
advantage of better transient response at low currents,
approximately constant frequency operation, and the ability
to maintain regulation when sinking current.
100
90 V IN = 75V
V IN = 25V
PULSE SKIP MODE
FORCED CONTINUOUS
80
70
60
V IN = 25V
0A
0A
50
V IN = 75V
40
30
0A
0A
20
10
0
PULSE SKIP MODE
FORCED CONTINUOUS
0A
3810 F01
0A
0.01
0.1
1
10
LOAD (A)
3810 F02
Figure 1. Comparison of Inductor Current Waveforms
for Pulse Skip Mode and Forced Continuous Operation
Figure 2. Ef?ciency in Pulse Skip Mode
and Forced Continuous Mode
3810fc
12
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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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