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参数资料
| 型号： | LM5117PMH |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING CONTROLLER, 530 kHz SWITCHING FREQ-MAX, PDSO20 |
| 封装： | TSSOP-20 |
| 文件页数： | 8/32页 |
| 文件大小： | 844K |
| 代理商： | LM5117PMH |
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30143215
FIGURE 10. Inductor Current
During an output short condition, the worst case peak inductor
current is limited to:
(12)
Where t
ON(MIN) is the minimum HO on-time.
If the saturation current of the inductor is less than I
LIM_PK, the
peak inductor current during output short condition may be
higher than I
LIM_PK. The temperatures of NMOS devices, Rs
and inductor should be checked under this condition.
Hiccup Mode Current Limiting
To further protect the regulator during prolonged current limit
conditions, LM5117 provides a hiccup mode current limit. An
internal hiccup mode fault timer counts the PWM clock cycles
during which cycle-by-cycle current limiting occurs. When the
hiccup mode fault timer detects 256 consecutive cycles of
current limiting, an internal restart timer forces the controller
to enter a low power dissipation standby mode and starts
sourcing 10
μA current into the RES pin capacitor C
RES. In this
standby mode, HO and LO outputs are disabled and the soft-
start capacitor C
SS is discharged.
C
RES is connected from RES pin to AGND and determines the
time (t
RES) in which the LM5117 remains in the standby before
automatically restarting. When the RES pin voltage exceeds
the 1.25V RES threshold, RES capacitor is discharged and a
soft-start sequence begins. t
RES can be calculated from the
following equation:
(13)
30143218
FIGURE 11. Hiccup Mode Current Limit Timing Diagram
30143219
FIGURE 12. Hiccup Mode Current Limit Circuit
The RES pin can also be configured for latch-off mode current
limiting or non-hiccup mode cycle-by-cycle current limiting. If
the RES pin is tied to VCC or a voltage greater than the RES
threshold at initial power-on, the restart timer is disabled and
the regulator operates with non-hiccup mode cycle-by-cycle
current limit. If the RES pin is tied to GND, the regulator enters
into the standby mode after 256 consecutive cycles of current
limiting and then never restarts until UVLO shutdown is cy-
cled. The restart timer is configured during initial power-on
when UVLO is above the UVLO threshold and VCC is above
the VCC UV threshold.
30143220
FIGURE 13. RES Configurations
www.national.com
16
LM5117
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LM5117PMH/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM5117PMH/NOPB | 制造商:Texas Instruments 功能描述:IC DC-DC CONV 750kHz TSSOP-20 制造商:Texas Instruments 功能描述:IC, DC-DC CONV, 750kHz, TSSOP-20 |
| LM5117PMHE/NOPB | 功能描述:DC/DC 开关控制器 Wide Input Range Sync Buck Cntlr RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM5117PMHX/NOPB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| LM5117PSQ/NOPB | 功能描述:DC/DC 开关控制器 Wide Input Range Sync Buck Cntlr RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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