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參數(shù)資料
| 型號： | L5973AD |
| 廠商： | STMICROELECTRONICS |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.3 A SWITCHING REGULATOR, PDSO8 |
| 封裝： | EXPOSED PAD, HSOP-8 |
| 文件頁數(shù)： | 3/22頁 |
| 文件大?。?/td> | 486K |
| 代理商： | L5973AD |
L5973AD
Functional description
Doc ID 9552 Rev 9
11/22
4.6
PWM comparator and power stage
This block compares the oscillator sawtooth and the error amplifier output signals
generating the PWM signal for the driving stage. The power stage is a very critical block
cause it has to guarantee a correct turn on and turn OFF of the PDMOS. The turn ON of the
power element, or better, the rise time of the current at turn on, is a very critical parameter to
compromise.
At a first approach, it looks like the faster it is the rise time, the lower are the turn on losses.
But there is a limit introduced by the recovery time of the recirculation diode. In fact when the
current of the power element equals the inductor current, the diode turns off and the drain of
the power is free to go high. But during its recovery time, the diode can be considered as an
high value capacitor and this produces a very high peak current, responsible of many
problems:
●
Spikes on the device supply voltage that cause oscillations (and thus noise) due to the
board parasitic.
●
Turn ON overcurrent causing a decrease of the efficiency and system reliability.
●
Big EMI problems.
●
Shorter freewheeling diode life.
The fall time of the current during the turn off is also critical. In fact it produces voltage
spikes (due to the parasites elements of the board) that increase the voltage drop across the
PDMOS.
In order to minimize all these problems, a new topology of driving circuit has been used and
its block diagram is shown in Figure 7.
The basic idea is to change the current levels used to turn on and off the power switch,
according with the PDMOS status and with the gate clamp status.
This circuitry allow to turn off and on quickly the power switch and to manage the above
question related to the freewheeling diode recovery time problem.
The gate clamp is necessary to avoid that Vgs of the internal switch goes higher than
Vgsmax. The ON/OFF Control block avoids any cross conduction between the supply line
and ground.
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相關(guān)代理商/技術(shù)參數(shù) |
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| L5973AD_07 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:2A switch step down switching regulator |
| L5973AD_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:2 A switch step down switching regulator |
| L5973ADTR | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 1.235 to 35V Step-Dn RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5973D | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 1.235 to 35V Step-Dn RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| L5973D_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:2.5 A switch step down switching regulator?癎 |
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