- 您现在的位置：买卖IC网 > PDF目录19958 > LT4254CGN#PBF (Linear Technology)IC CTRLR HOTSWAP POSVOLT 16SSOP PDF资料下载
参数资料
| 型号： | LT4254CGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 232K |
| 描述： | IC CTRLR HOTSWAP POSVOLT 16SSOP |
| 标准包装： | 100 |
| 类型： | 热交换控制器 |
| 应用： | 通用 |
| 内部开关： | 无 |
| 电源电压： | 10.8 V ~ 36 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 管件 |
| 产品目录页面： | 1341 (CN2011-ZH PDF) |
LT4254
11
4254fb
Layout Considerations section for important information
about board layout to minimize current limit threshold
error.
The LT4254 also features a variable overcurrent response
time. The time required for the part to regulate the GATE
pin voltage is a function of the voltage across the sense
resistor connected between the V
CC
pin and the SENSE pin.
This helps to eliminate sensitivity to current spikes and tran-
sients that might otherwise unnecessarily trigger a current
limit response and increase MOSFET dissipation. Figure 8
shows the response time as a function of the overdrive at
the SENSE pin.
TIMER
The TIMER pin provides a method for programming the
maximum time the part is allowed to operate in current
limit. When the current limit circuitry is not active, the
TIMER pin is pulled to GND by a 3礎 current source. When
the current limit circuitry becomes active, a 123礎 pull-up
current source is added to the TIMER pin and the voltage
will rise with a slope equal to 120礎/C
TIMER
as long as the
circuitry stays active. Once the desired maximum current
limit time is known, the capacitor value is:
C(nF) = 25.8 " t(ms)
Whenever the TIMER pin reaches 4.65V (typ), the internal
fault latch is set causing the GATE to be pulled low and the
TIMER pin to be discharged to GND by the 3礎 current
source. The part is not allowed to turn on again until the
voltage at the TIMER pin falls below 0.65V (typ).
The TIMER pin must never be pulled high by a low
impedance because whenever the TIMER pin voltage rises
above the upper threshold (typically 4.65V) the pin char-
acteristics change from a high impedance current source
to a low impedance. If the pin must be pulled high by a logic
signal, then a resistor must be put in series with the TIMER
pin to limit the current to approximately 100 microam-
peres. The resistance should be chosen as follows:
R
SERIES
= (V
LOGIC
4.65V)/100礎
Whenever the GATE pin is commanded off by any fault
condition, it is discharged with a high current, turning off
the external MOSFET. The waveform in Figure 9 shows how
the output latches off following a short-circuit. The drop
across the sense resistor is held at 12mV as the timer ramps
up. Since the output did not rise bringing FB above 2V and
the current is still 12mV/R5, the circuit latches off.
Automatic Restart
If the RETRY pin is floating, then the functionality is as
described in the previous section.
When the voltage at the TIMER pin ramps back down to
0.65V (typ), the LT4254 turns on again. If the short-circuit
condition at the output still exists, the cycle will repeat
itself indefinitely. The duty cycle under short-circuit con-
ditions is 3% which prevents Q1 from overheating.
Latch Off Operation
If the RETRY pin is grounded, the LT4254 will latch off
after a current fault. After the part latches off, it may be
APPLICATIO S I FOR ATIO
U
U
U
12mV
0V
2V
FB
4254 F07
50mV
V
CC
V
SENSE
50
100
150
200
4254 F08
12
10
8
6
4
2
V
CC
V
SENSE
(mV)
0
Figure 7. Current Limit Sense Voltage vs Feedback Pin Voltage
Figure 8. Response Time to Overcurrent
相关PDF资料 |
PDF描述 |
|---|---|
| ES1B-13-F | DIODE SUPER FAST 100V 1A SMD |
| GJM0335C1E3R3CB01D | CAP CER 3.3PF 25V NP0 0201 |
| VI-2TZ-CV | CONVERTER MOD DC/DC 2V 60W |
| VE-JW3-CY-B1 | CONVERTER MOD DC/DC 24V 50W |
| T86E227M6R3EAAL | CAP TANT 220UF 6.3V 20% 2917 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT4254IGN | 功能描述:IC CTLR HOTSWAP POS 16-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LT4254IGN#PBF | 功能描述:IC CTLR HOTSWAP POS 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LT4254IGN#TR | 功能描述:IC CTLR HOTSWAP POS 16-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LT4254IGN#TRPBF | 功能描述:IC CTLR HOTSWAP POS 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LT4256 | 制造商:LINER 制造商全称:Linear Technology 功能描述:High Voltage Surge |
发布紧急采购，3分钟左右您将得到回复。