參數(shù)資料
型號(hào)： TPS40009DGQRG4
廠(chǎng)商： TEXAS INSTRUMENTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 700 kHz SWITCHING FREQ-MAX, PDSO10
封裝： 3.05 X 4.98 MM, GREEN, PLASTIC, MSOP-10
文件頁(yè)數(shù)： 4/28頁(yè)
文件大?。?/td> 677K
代理商： TPS40009DGQRG4
TPS40007
TPS40009
SLUS589B NOVEMBER 2003 REVISED FEBRUARY 2005
12
www.ti.com
APPLICATION INFORMATION
SS/SD pin falls below 260 mV. Because of this limitation, it is recommended that a MOSFET be used as the
controlling device, as in Figure 6. During shutdown, the total leakage current on the SW pin (ISW) is less than
2
A. When VSS/SD is greater than 290 mV, the device is enabled with normal SW active bias currents.
SS/SD
4
TPS40007/9
CSS
SHUTDOWN
+
0.26 V
SDN
+
0.7 V
FB
ERROR AMPLIFIER
COMP
R
UDG01163
3.7
A
Figure 6. Shutdown Implementation
Long soft start times may experience extended regions where the PWM pulse width is less than 100 ns. This
could lead to momentary overlap between HDRV and LDRV. As a result, there is a momentary increase in
ground or supply noise. It is important to ensure that the ground return of the synchronous rectifier be connected
directly to the ground return of the input bank of bypass capacitors, in order to minimize ground noise from
interfering with the controller during soft start. Also, if an external shutdown transistor is used in the application,
it is important to place a local bypass capacitor between its gate and source on the board in order to minimize
noise from interfering with the controller during soft-start.
OUTPUT PRE-BIAS
The TPS4000x supports pre-biased VOUT voltage applications. In cases, where the VOUT voltage is held up by
a pre-biasing supply while the controller is off, full synchronous rectification is disabled during the initial phase
of soft starting the VOUT voltage. When the first PWM pulses are detected during soft-start, the controller slowly
activates synchronous rectification by starting the first LDRV pulses 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 (1D), where D is the duty cycle
of the converter. This scheme prevents the initial sinking the pre-bias output, and ensures that the VOUTvoltage
starts and ramps up smoothly into regulation. Note, if the VOUT voltage is pre-biased, PWM pulses start when
the error amplifier soft-start input voltage rises above the commanded FB voltage.
Figure 7 depicts the waveforms 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 cycle, the leading edge of LDRV is modulated, and the on-time of the synchronous rectifier
is increased. Eventually, the leading edge of LDRV coincides with the falling edge of HDRV to achieve full
synchronous rectification.
At most, synchronous rectifier modulation takes place for the first 128 cycles after PWM pulses start. Note that
during the synchronous rectifier modulation region, the controller monitors pulse skipping. If the main HDRV
skips a pulse, the controller also skips a LDRV pulse. Pulse skipping could be experienced if the loop response
is much faster than the commanding soft-start ramp, especially when soft start times are long. The output
voltage ratchets up as the soft-start ramp catches up to it. Appropriate setting of loop response curbs this effect.
During normal regulation of the VOUT voltage, the controller operates in full two-quadrant source/sink mode.
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TPS40020 制造商:TI 制造商全稱(chēng):Texas Instruments 功能描述:ENHANCED LOW INPUT VOLTAGE MODE SYNCHRONOUS BUCK CONTROLLER
TPS40020PWP 功能描述:DC/DC 開(kāi)關(guān)控制器 Enhanced Low Input 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
TPS40020PWPG4 功能描述:DC/DC 開(kāi)關(guān)控制器 Enh Lo Input Freq Sync. 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
TPS40020PWPR 功能描述:DC/DC 開(kāi)關(guān)控制器 Enh Lo Input Freq Sync. 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
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