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参数资料
| 型号： | LT1950EGN#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 14/20页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR PWM CM 16-SSOP |
| 标准包装： | 2,500 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 560kHz |
| 占空比： | 97% |
| 电源电压： | 3 V ~ 25 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： | 是 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
LT1950
APPLICATIO S I FOR ATIO
BLANKING ( EXTENDED ) = 110 + ? 60 ? BLANK ? ns
Programming Leading Edge Blank Time
For PWM controllers driving external MOSFETs, noise can
be generated during GATE rise time due to various para-
sitic effects. This noise can disturb the input to the current
sense comparator (I SENSE ) and cause premature turn-off
of the external MOSFET. The LT1950 provides program-
mable leading edge blanking of the current sense com-
parator to avoid this effect.
Blanking is provided in 2 phases: The first phase is during
GATE rise time. GATE rise times vary depending on
MOSFET type. For this reason the LT1950 automatically
blanks the current comparator output until the “leading
edge” of the GATE is detected. This occurs when the GATE
voltage has risen within 0.5V of the output driver supply
(V IN2 ) or has reached its clamp level of 13V. The second
phase of blanking starts immediately after “leading edge”
has been detected. This phase is programmable using a
resistor (R BLANK ) from the BLANK pin to ground. Typical
values for this portion of the blanking period are 110ns at
R BLANK = 0 ? up to 290ns at R BLANK = 75k. Figure 8 shows
blanking vs R BLANK . Blanking duration can be approxi-
mated as:
? R ?
? 25 k ?
(AUTOMATIC) (DEFAULT)
LEADING
Programming Volt-Second Clamp
The V SEC pin is used to provide an adaptive maximum duty
cycle clamp for sophisticated control of the simplest
forward converter topology (single primary-side switch).
This adaptive maximum duty cycle clamp allows the use of
the smallest transformers, MOSFETs and output rectifiers
by addressing the biggest concern in single switch for-
ward converter topologies - transformer reset. The sec-
tion “Application Circuits-Forward Converter Applications”
covers transformer reset requirements and highlights the
advantages of the LT1950 adaptive maximum duty cycle
clamp. The programmable maximum duty cycle clamp is
controlled by the voltage on the V SEC pin. As voltage on the
V SEC pin increases within a specified range, maximum
duty cycle decreases. By deriving V SEC pin voltage from
the system input supply, a volt-second clamp is realized.
Maximum GATE output duty cycle follows a 1/X relation-
ship given by (105/V SEC )%. (see Maximum Duty Cycle vs
V SEC Voltage graph in the Typical Performance Character-
istics section). For example, if the minimum input supply
for a forward converter application is 36V, the V SEC pin can
be programmed with a maximum duty cycle of 75% at
1.4V. A movement of input voltage to 72V will lift the V SEC
pin to 2.8V, resulting in a maximum duty cycle of 37.5%.
As the section on Forward Converter Applications will
show, transformer reset requirements are met with the
(PROGRAMMABLE)
CURRENT
GATE
EDGE
BLANKING
EXTENDED
BLANKING
R BLANK = 0 ?
EXTENDED
BLANKING
0 ? < R BLANK < = 75k
SENSE
DELAY
60ns
BLANKING
0
Xns
(X + 110)ns
[X + 110 + (60 ? R BLANK /25k)]ns
1950 F04
Figure 8. Blanking Timing Diagram
1950fa
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1950IGN | 功能描述:IC REG CTRLR PWM CM 16-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: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) |
| LT1950IGN#PBF | 功能描述:IC REG CTRLR PWM CM 16-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:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 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:8-TSSOP（0.173"，4.40mm 宽） 包装:带卷 (TR) |
| LT1950IGN#TR | 功能描述:IC REG CTRLR PWM CM 16-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: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) |
| LT1950IGN#TRPBF | 功能描述:IC REG CTRLR PWM CM 16-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: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) |
| LT1952 | 制造商:LINER 制造商全称:Linear Technology 功能描述:2-Phase Step-Up DC/DC Controller |
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