參數(shù)資料
型號(hào)： TPS62250DRVR
廠商： TEXAS INSTRUMENTS INC
元件分類： 穩(wěn)壓器
英文描述： SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, PDSO6
封裝： 2 X 2 MM, 0.80 MM HEIGHT, GREEN, PLASTIC, SON-6
文件頁(yè)數(shù)： 8/29頁(yè)
文件大?。?/td> 1207K
代理商： TPS62250DRVR
DETAILED DESCRIPTION
OPERATION
POWER SAVE MODE
Dynamic Voltage Positioning
SLVS842 – SEPTEMBER 2008.......................................................................................................................................................................................... www.ti.com
The TPS62250 step down converter operates with typically 2.25 MHz fixed frequency pulse width modulation
(PWM) at moderate to heavy load currents. At light load currents the converter can automatically enter Power
Save Mode and operates then in PFM mode.
During PWM operation the converter use a unique fast response voltage mode control scheme with input voltage
feed-forward to achieve good line and load regulation allowing the use of small ceramic input and output
capacitors. At the beginning of each clock cycle initiated by the clock signal, the High Side MOSFET switch is
turned on. The current flows now from the input capacitor via the High Side MOSFET switch through the inductor
to the output capacitor and load. During this phase, the current ramps up until the PWM comparator trips and the
control logic will turn off the switch. The current limit comparator will also turn off the switch in case the current
limit of the High Side MOSFET switch is exceeded. After a dead time preventing shoot through current, the Low
Side MOSFET rectifier is turned on and the inductor current will ramp down. The current flows now from the
inductor to the output capacitor and to the load. It returns back to the inductor through the Low Side MOSFET
rectifier.
The next cycle will be initiated by the clock signal again turning off the Low Side MOSFET rectifier and turning on
the on the High Side MOSFET switch.
The Power Save Mode is enabled with MODE Pin set to low level. If the load current decreases, the converter
will enter Power Save Mode operation automatically. During Power Save Mode the converter skips switching and
operates with reduced frequency in PFM mode with a minimum quiescent current to maintain high efficiency. The
converter will position the output voltage typically +1% above the nominal output voltage. This voltage positioning
feature minimizes voltage drops caused by a sudden load step.
The transition from PWM mode to PFM mode occurs once the inductor current in the Low Side MOSFET switch
becomes zero, which indicates discontinuous conduction mode.
During the Power Save Mode the output voltage is monitored with a PFM comparator. As the output voltage falls
below the PFM comparator threshold of VOUT nominal +1%, the device starts a PFM current pulse. The High
Side MOSFET switch will turn on, and the inductor current ramps up. After the On-time expires, the switch is
turned off and the Low Side MOSFET switch is turned on until the inductor current becomes zero.
The converter effectively delivers a current to the output capacitor and the load. If the load is below the delivered
current, the output voltage will rise. If the output voltage is equal or higher than the PFM comparator threshold,
the device stops switching and enters a sleep mode with typical 15
A current consumption.
If the output voltage is still below the PFM comparator threshold, a sequence of further PFM current pulses are
generated until the PFM comparator threshold is reached. The converter starts switching again once the output
voltage drops below the PFM comparator threshold.
With a fast single threshold comparator, the output voltage ripple during PFM mode operation can be kept small.
The PFM Pulse is time controlled, which allows to modify the charge transferred to the output capacitor by the
value of the inductor. The resulting PFM output voltage ripple and PFM frequency depend in first order on the
size of the output capacitor and the inductor value. Increasing output capacitor values and inductor values will
minimize the output ripple. The PFM frequency decreases with smaller inductor values and increases with larger
values.
The PFM mode is left and PWM mode entered in case the output current can not longer be supported in PFM
mode. The Power Save Mode can be disabled through the MODE pin set to high. The converter will then operate
in fixed frequency PWM mode.
This feature reduces the voltage under/overshoots at load steps from light to heavy load and vice versa. It is
active in Power Save Mode and regulates the output voltage 1% higher than the nominal value. This provides
more headroom for both the voltage drop at a load step, and the voltage increase at a load throw-off.
16
Copyright 2008, Texas Instruments Incorporated
Product Folder Link(s): TPS62250
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TPS62250DRVTG4 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2.25MHz,1A Peak Crnt Ltd Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
TPS62260DDCR 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2.25MHz 600mA Step- Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
TPS62260DDCRG4 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 2.25MHz 600mA Step- Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
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