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| 型号： | TPS40074RHL |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 2 A SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封装： | PLASTIC, QFN-20 |
| 文件页数： | 11/37页 |
| 文件大小： | 448K |
| 代理商： | TPS40074RHL |
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TPS40074 POWER DISSIPATION
PD + Qg VDR fSW (Watts driver)
(12)
PT +
2
PD
VDR
) IQ
VIN (Watts)
(13)
PT + 2 Qg fSW ) IQ
VIN (Watts)
(14)
PT +
TJ * TA
qJA
(Watts)
(15)
fSW +
TJ*TA
qJA VIN
* IQ
2
Qg
(Hz)
(16)
BOOST DIODE
LOW VOLTAGE OPERATION
TPS40074
SLUS617–APRIL 2005
APPLICATION INFORMATION (continued)
The power dissipation in the TPS40074 is largely dependent on the MOSFET driver currents and the input
voltage. The driver current is proportional to the total gate charge, Qg, of the external MOSFETs. Driver power
(neglecting external gate resistance) can be calculated from:
where
VDR is the driver output voltage
The total power dissipation in the TPS40074, assuming the same MOSFET is selected for both the high-side and
synchronous rectifier is described in Equation 13.
or
where
IQ is the quiescent operating current (neglecting drivers)
The maximum power capability of the TPS40074 PowerPAD package is dependent on the layout as well as air
flow. The thermal impedance from junction to air ambient assuming 2-oz. copper trace and thermal pad with
solder and no air flow is θJA =60°C/W
The maximum allowable package power dissipation is related to ambient temperature by Equation 15.
Substituting Equation 15 into Equation 14 and solving for fSW yields the maximum operating frequency for the
TPS4007x. The result is described in Equation 16.
The TPS40074 has internal diodes to charge the boost capacitor connected from SW to BOOST. The drop
across this diode is rather large at 1.4-V nominal at room temperature resulting in the drive voltage to the
high-side MOSFET being reduced by this amount from the DBP voltage. If this drop is too large for a particular
application, an external diode may be connected from DBP (anode) to BOOST (cathode). This provides
significantly improved gate drive for the high-side MOSFET, especially at lower input voltages.
If the programmable UVLO is set to less than 6.5 V nominal, connect a 330-k resistor across the soft-start
capacitor. This eliminates a race condition inside the device that can lead to an output voltage overshoot on
power down of the part.
19
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS40074RHLR | 功能描述:DC/DC 开关控制器 Mid Input Sync Buck w/Vltg Feed-Fwd 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 |
| TPS40074RHLRG4 | 功能描述:DC/DC 开关控制器 Mid Input Sync Buck w/Vltg Feed-Fwd 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 |
| TPS40074RHLT | 功能描述:DC/DC 开关控制器 Mid Input Sync Buck w/Vltg Feed-Fwd 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 |
| TPS40074RHLTG4 | 功能描述:DC/DC 开关控制器 Mid Input Sync Buck w/Vltg Feed-Fwd 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 |
| TPS40075 | 制造商:TI 制造商全称:Texas Instruments 功能描述:4.5V TO 18V INPUT 10 PIN SYNCHRONOUS BUCK CONTROLLER WITH POWER GOOD |
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