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参数资料
| 型号： | LTC3873ETS8#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 8/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BST FLYBK TSOT23-8 |
| 标准包装： | 500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 240kHz |
| 占空比： | 84% |
| 电源电压： | 8.8 V ~ 75 V |
| 降压： | 无 |
| 升压： | 是 |
| 回扫： | 是 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | SOT-23-8 薄型，TSOT-23-8 |
| 包装： | 带卷 (TR) |
LTC3873
OPERATION
(nominally 8.4V) at least momentarily to enable LTC3873
operation. The V CC voltage is then allowed to fall to V TURNOFF
(nominally 4V) before undervoltage lockout disables the
LTC3873. This wide UVLO hysteresis range supports the
use of trickle charger on the ?yback transformer to power
the LTC3873—see the section, V CC Bias Power. The RUN/SS
pin can be driven below V SHDN (nominally 0.7V) to force
the LTC3873 into shutdwn. When the chip is off, the input
supply current is typically only 55μA.
Soft-Start
Leave the RUN/SS pin open to use the internal 3.3ms
soft-start. During the internal soft-start, a voltage ramp
limits the V ITH . 3.3ms is required for I TH to ramp from
zero current level to full current level. The soft-start can
be lengthened by placing an external capacitor from the
RUN/SS pin to the GND. A 3μA current will charge the
capacitor, pulling the RUN/SS pin above the shutdown
threshold and a 15μA pull-up current will continue to ramp
RUN/SS to limit V ITH during the start-up. When RUN/SS
is driven by an external logic, a minimum of 2.75V logic
is recommended to allow the maximum I TH range.
300
Light Load Operation
Under very light load current conditions, the I TH pin volt-
age will be very close to the zero current level of 0.85V.
As the load current decreases further, an internal offset at
the current comparator input will assure that the current
comparator remains tripped (even at zero load current) and
the regulator will start to skip cycles in order to maintain
regulation. This behavior allows the regulator to maintain
constant frequency down to very light loads, resulting in low
output ripple as well as low audible noise and reduced RF
interference while providing high light load ef?ciency.
Current Sense
During the switch on-time, the control circuit limits the
maximum voltage drop across the current sense com-
ponent to about 295mV, 110mV and 185mV at low duty
cycle with IPRG tied to V IN , GND or left ?oating respec-
tively. It is reduced with increasing duty cycle as shown
in Figure 4.
250
200
IPRG = HIGH
IPRG = FLOAT
150
IPRG = LOW
100
50
0
1
20
40 60
80
100
DUTY CYCLE (%)
3873 F04
Figure 4. Maximum SENSE Threshold Voltage vs Duty Cycle
3873fa
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC3873IDDB-5#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Isolated, Cut Tape No Rsense Constant Frequency Current Mode Boost/Flyb |
| LTC3873IDDB-5#TRMPBF | 功能描述:IC REG CTRLR BST FLYBK PWM 8-DFN 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) |
| LTC3873IDDB-5#TRPBF | 功能描述:IC REG CTRLR BST FLYBK PWM 8-DFN 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) |
| LTC3873ITS8-5#PBF | 制造商:Linear Technology 功能描述:DP-SWREG/Isolated, Cut Tape No Rsense Constant Frequency Current Mode Boost/Flyb |
| LTC3873ITS8-5#TRMPBF | 功能描述:IC REG CTRLR BST FLYBK TSOT23-8 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) |
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