- 您現(xiàn)在的位置：買(mǎi)賣IC網(wǎng) > PDF目錄98281 > TPS40042DRCTG4 (TEXAS INSTRUMENTS INC) SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10 PDF資料下載
參數(shù)資料
| 型號(hào)： | TPS40042DRCTG4 |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10 |
| 封裝： | 3 X 3 MM, GREEN, PLASTIC, SON-10 |
| 文件頁(yè)數(shù)： | 4/35頁(yè) |
| 文件大小： | 746K |
| 代理商： | TPS40042DRCTG4 |
第1頁(yè)第2頁(yè)第3頁(yè)當(dāng)前第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)第17頁(yè)第18頁(yè)第19頁(yè)第20頁(yè)第21頁(yè)第22頁(yè)第23頁(yè)第24頁(yè)第25頁(yè)第26頁(yè)第27頁(yè)第28頁(yè)第29頁(yè)第30頁(yè)第31頁(yè)第32頁(yè)第33頁(yè)第34頁(yè)第35頁(yè)
www.ti.com
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
Output Short Circuit Protection
SLUS777 – NOVEMBER 2007
The TPS40042 supports pre-biased output voltage applications. In cases where the output voltage is held up by
external means while the TPS40042 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 16 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 TPS40042 operates in full two
quadrant source/sink mode.
Figure 17 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 16. MOSFET Drivers at Beginning of Soft Start
Figure 17. Startup Waveforms; VREFIN = 0.6 V
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 TPS40042 turns ON the Synchronous Rectifier, therby drawing current
from the output to bring the output voltage into regulation. Note that this may cause some undershoot of the
output voltage before entering regulation.
To minimize circuit losses, the TPS40042 uses the RDS(on) of the upper MOSFET switch as the current sensing
element. The current limit comparator, initially blanked during the first portion of each switching cycle, senses the
voltage across the high-side MOSFET when it is fully ON. This voltage is compared to an internally selected
short circuit current (SCC) limit threshold voltage. If the comparator senses a voltage drop across the high-side
MOSFET greater than the SCC limit threshold, it outputs an OC pulse. This terminates the current PWM pulse
12
Copyright 2007, Texas Instruments Incorporated
Product Folder Link(s): TPS40042
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| TPS40055MPWPREPG4 | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS40055QPWPRQ1 | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS40054QPWPRQ1 | SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS40070PWPRG4 | 2 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS40071PWPR | 2 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS40050 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:WIDE-INPUT SYNCHRONOUS BUCK CONTROLLER |
| TPS40050PWP | 功能描述:DC/DC 開(kāi)關(guān)控制器 Wide Input Vltg Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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 |
| TPS40050PWPG4 | 功能描述:DC/DC 開(kāi)關(guān)控制器 Wide Input Vltg Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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 |
| TPS40050PWPR | 功能描述:DC/DC 開(kāi)關(guān)控制器 Wide Input Vltg Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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 |
| TPS40050PWPRG4 | 功能描述:DC/DC 開(kāi)關(guān)控制器 Wide Input Vltg Synch Buck Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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 |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。