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參數(shù)資料
| 型號： | LM5045MH |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 540 kHz SWITCHING FREQ-MAX, PDSO28 |
| 封裝： | ETSSOP-28 |
| 文件頁數(shù)： | 14/28頁 |
| 文件大小： | 610K |
| 代理商： | LM5045MH |
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FIGURE 11. Input Transient Protection
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FIGURE 12. Start-up Regulator for VPWR>100V
UVLO AND OVP VOLTAGE DIVIDER SELECTION
Two dedicated comparators connected to the UVLO and OVP
pins are used to detect under voltage and over voltage con-
ditions. The threshold values of both these comparators are
set at 1.25V. The two functions can be programmed inde-
pendently with two separate voltage dividers from VIN to
AGND as shown in Figure 13 and 14, or with a three-resistor
divider as shown in Figure 15. Independent UVLO and OVP
pins provide greater flexibility for the user to select the oper-
ational voltage range of the system. When the UVLO pin
voltage is below 0.4V, the controller is in a low current shut-
down mode. For a UVLO pin voltage greater than 0.4V but
less than 1.25V the controller is in standby mode. Once the
UVLO pin voltage is greater than 1.25V, the controller is fully
enabled. Two external resistors can be used to program the
minimum operational voltage for the power converter as
shown in Figure 13. When the UVLO pin voltage falls below
the 1.25V threshold, an internal 20A current sink is enabled
to lower the voltage at the UVLO pin, thus providing threshold
hysteresis. Resistance values for R
1 and R2 can be deter-
mined from the following equations:
Where V
PWR is the desired turn-on voltage and VHYS is the
desired UVLO hysteresis at V
PWR.
For example, if the LM5045 is to be enabled when VPWR
reaches 33V, and disabled when V
PWR is decreased to 31V,
R
1 should be 100k, and R2 should be 4.2k. The voltage at
the UVLO pin should not exceed 7V at any time.
Two external resistors can be used to program the maximum
operational voltage for the power converter as shown in Fig-
ure 13. When the OVP pin voltage rises above the 1.25V
threshold, an internal 20A current source is enabled to raise
the voltage at the OVP pin, thus providing threshold hystere-
sis. Resistance values for R
1 and R2 can be determined from
the following equations:
If the LM5045 is to be disabled when V
PWR-OFF reaches 80V
and enabled when it is decreased to 78V. R
1 should be
100k
, and R
2 should be 1.5 k. The voltage at the OVP pin
should not exceed 7V at any time.
21
www.national.com
LM5045
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM5045MH/NOPB | 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| LM5045MHX | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Full-Bridge PWM Controller with Integrated MOSFET Drivers |
| LM5045MHX/NOPB | 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
| LM5045SQ | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Full-Bridge PWM Controller with Integrated MOSFET Drivers |
| LM5045SQ/NOPB | 功能描述:電流型 PWM 控制器 Full-Bridge PWM Cntrlr RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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