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参数资料
| 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： | 20/37页 |
| 文件大小： | 448K |
| 代理商： | TPS40074RHL |
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CBOOST u
Qg(TOTAL)
DVBOOST
(42)
KPWM ^
VUVLO
1V
(43)
KLC +
1 ) s
ESR
CO
1 ) s
L
RLOAD
) s2
L
CO
(44)
Ge(s) + KPWM KLC +
VUVLO
1V
1 ) s
ESR
CO
1 ) s
L
RLOAD
) s2
L
CO
(45)
DCGAIN + 20
LOG
VUVLO
1V
+ 20
LOG(8.752) + 18.8 dB
(46)
TPS40074
SLUS617–APRIL 2005
3.2.5 Voltage Decoupling Capacitors, CDBP,CLVBP and CVDD
Several pins on the TPS40074 have DC voltages. It is recommended to add small decoupling capacitors to these
pins. Below is a list of the recommended values.
CDBP =1.0 F
CLVBP =0.1 F
CVDD =4.7 F
3.2.6 Boost Voltage, CBOOST and DBOOST (optional)
A capacitor charge pump or boost circuit is required to drive an N-channel MOSFET in the switch location of a
buck converter . The TPS40074 contains the elements for this boost circuit. The designer just has to add a
capacitor, CBOOST, from the switch node of the buck power stage to the BOOST pin of the device. Selection of
this capacitor is based on the total gate charge of the switching MOSFET and the allowable ripple on the boost
voltage, VBOOST. A ripple of 0.15 V is assumed for this design. Using these two parameters and Equation 42 the
minimum value for CBOOST can be calculated.
The total gate charge of the switching MOSFET is 13.3 nC. A minimum CBOOST of 0.089 F is required. A 0.1 F
capacitor was chosen.
This capacitor must be able to withstand the maximum voltage on DBP (10 V in this instance ). A 50 V capacitor
is used for expediancy.
To reduce losses in the TPS40074 and to increase the available gate voltage for the switching MOSFET an
external diode can be added between the DBP pin and the BOOST pin of the device. A small signal schottky
should be used here, such as the BAT54.
3.3 Closing the Feedback Loop, RZ1,RP1,RPZ2,RSET1,RSET2,CZ2,CP2 and CPZ1
A graphical method is used to select the compensation components. This is a standard feedforward buck
converter. Its PWM gain is shown in Equation 43.
The gain of the output L-C filter is given by Equation 44
The PWM and LC gain is, shown in Equation 45.
To describe this in a Bode plot, the DC gain must be expressed in dB. The DC gain is equal to KPWM. To express
this in dB we take its LOG and multiple by 20. For this converter the DC gain is shown in Equation 46.
The pole and zero frequencies should be calculated, also. A double pole is associated with the L-C and a zero is
associated with the ESR of the output capacitor. The frequency at where these occur can be calculated using the
following two equations.
27
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相关代理商/技术参数 |
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|---|---|
| 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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