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參數(shù)資料
| 型號(hào)： | TPS40040DRBT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 7.2 A SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 3 X 3 MM, PLASTIC, SON-8 |
| 文件頁數(shù)： | 4/38頁 |
| 文件大?。?/td> | 741K |
| 代理商： | TPS40040DRBT |
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Pre-Bias Startup
t Time 2
s/div
VHDRV
VLDRV
t Time 500
s/div
VIN = 5 V
VOUT = 1.2 V
(200 mV/div)
PREBIAS = 0 V
PREBIAS = 0.5 V
PREBIAS = 1 V
SLUS700D – MARCH 2006 – REVISED DECEMBER 2007
The TPS40040/1 supports pre-biased output voltage applications. In cases where the output voltage is held up
by external means while the TPS40040/1 is off, full synchronous rectification is disabled during the initial phase
of soft starting the output voltage. When the first PWM pulses are detected during soft start, the controller slowly
initiates synshronous rectification by starting the synchronous rectifier with a narrow on time. It then increments
that on time on a cycle-by-cycle basis until it coincides with the time dictated by (1-D), where D is the duty cycle
of the converter. This approach prevents the sinking of current from a pre-biased output, and ensures the output
voltage startup and ramp to regulation is smooth and controlled.
NOTE:
If the output is pre-biased, PWM pulses start when the internal soft-start voltage rises
above the error amplifier input (FB pin).
Figure 20 below depicts the waveform of the HDRV and LDRV output signals at the beginning PWM pulses.
When HDRV turns off, diode rectification is enabled. Before the next PWM cycle starts, LDRV is turned on for a
short pulse. With every clock cycle, the leading edge of LDRV is modulated, increasing the on time of the
synchronous rectifier. Eventually, the leading edge of LDRV coincides with the falling edge of HDRV to achieve
full synchronous rectification. During normal operation of the converter, the TPS40040/1 operates in full two
quadrant source/sink mode.
Figure 21 shows the startup waveform of a 1.2-V output converter under three different pre-biased output
conditions. The lowest trace is when there is no pre-bias on the output. The center and top most traces indicate
converter startup with 0.5-V and 1.0-V pre-bias conditions.
Figure 20. MOSFET Drivers at Beginning of Soft Start
Figure 21. Startup Waveforms
The recommended output voltage pre-bias range is less than or equal to 90% of the final regulation voltage. A
pre-biased output voltage of 90% to 100% of final regulation could lead to the sinking of current from the pre-bias
source. If the pre-biased voltage is greater than the designed converter output regulation voltage, then upon the
completion of the soft-start interval, the TPS40040/1 draws current from the output to bring the output voltage
into regulation.
12
Copyright 2006–2007, Texas Instruments Incorporated
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS40040DRBT | 制造商:Texas Instruments 功能描述:Peak Reflow Compatible (260 C):Yes |
| TPS40040DRBTG4 | 功能描述:DC/DC 開關(guān)控制器 Lo Vin Synch Buck DC/DC Cntrlr 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 |
| TPS40040EVM-001 | 功能描述:電源管理IC開發(fā)工具 10A Synch Buck Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| TPS40041 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:LOW PIN COUNT, LOW VIN (2.5 V TO 5.5 V) SYNCHRONOUS BUCK DC-TO-DC CONTROLLER WITH ENABLE |
| TPS40041DRBR | 功能描述:DC/DC 開關(guān)控制器 Low Vin Synch Buck DC/DC Controller 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 |
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