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參數(shù)資料
| 型號： | TPS40074RHL |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2 A SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | PLASTIC, QFN-20 |
| 文件頁數(shù)： | 17/37頁 |
| 文件大小： | 448K |
| 代理商： | TPS40074RHL |
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PQSW + PQSW(CON) ) PQSW(SW) ) PQSW(GATE)
(25)
PQSW(CON) + RDS(on) ID
2 + R
DS(on)
VO
VIN
ILOAD
2 ) DI
2
12
(26)
PQSW(SW) + VIN fSW
ILOAD ) DI2
Qgs1 ) Qgd
Ig
)
QOSS(SW) ) QOSS(SR)
2
(27)
PQSW(GATE) + Qg(TOT) Vg FSW
(28)
TPS40074
SLUS617–APRIL 2005
Equation 25 through Equation 28 can be used to calculate the power loss, PQSW, in the switching MOSFET
where
PQSW(CON) = conduction losses
PQSW(SW) = switching losses
PQSW(GATE) = gate drive losses
Qgd = drain source charge or miller charge
Qgs1 = gate source post threshold charge
Ig = gate drive current
QOSS(SW) = switching MOSFET output charge
QOSS(SR) = synchronous MOSFET output charge
Qg(TOT) = total gate charge from zero volts to the gate voltage
Vg = gate voltage
If the total estimated loss is split evenly between conduction and switching losses, Equation 25 and Equation 26
yields preliminary values for RDS(on) and (Qgs1 +Qgd). Note output losses due to QOSS and gate losses have been
ignored here. Once a MOSFET is selected these parameters can be added.
The switching MOSFET for this design should have an RDS(on) of less than 9 m.The sumofQgd and Qgs should
be approximately 4 nC.
It is not always possible to get a MOSFET which meets both these criteria so a comprise may have to be made.
Also by selecting different MOSFETs close to this criteria and calculating power loss the final selection can be
made. It was found that the PH6325L MOSFET from Philips semiconductor gave reasonable results. This device
has an RDS(on) of 6.3 m and a (Qgs1+Qgd) of 5.9 nC. The estimated conduction losses are 0.178 W and the
switching losses are 0.270 W. This gives a total estimated power loss of 0.448 W versus 0.5 W for our initial
boundary condition. Note this does not include gate losses of approximately 10 mW and output losses of less
than1mW.
3.1.5 Rectifier MOSFET, QSR
Similar criteria can be used for the rectifier MOSFET. There is one significant difference. Due to the body diode
conducting, the rectifier MOSFET switches with near zero voltage across its drain and source so effectively with
near zero switching losses. However, there are some losses in the body diode. These are minimized by reducing
the delay time between the transition from the switching MOSFET turn off to rectifier MOSFET turn on and vice
versa. The TPS40074 incorporates TI's proprietary predictive gate drive which helps reduce this delay to
between 10 ns and 20 ns.
24
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參數(shù)描述 |
|---|---|
| TPS40074RHLR | 功能描述:DC/DC 開關(guān)控制器 Mid Input Sync Buck w/Vltg Feed-Fwd RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| TPS40074RHLRG4 | 功能描述:DC/DC 開關(guān)控制器 Mid Input Sync Buck w/Vltg Feed-Fwd RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| TPS40074RHLT | 功能描述:DC/DC 開關(guān)控制器 Mid Input Sync Buck w/Vltg Feed-Fwd RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| TPS40074RHLTG4 | 功能描述:DC/DC 開關(guān)控制器 Mid Input Sync Buck w/Vltg Feed-Fwd RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| TPS40075 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4.5V TO 18V INPUT 10 PIN SYNCHRONOUS BUCK CONTROLLER WITH POWER GOOD |
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