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參數資料
| 型號： | TPS62228DDC |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | 400-mA, 1.25-MHz, HIGH-EFFICIENCY, STEP-DOWN CONVERTER IN THIN-SOT23 |
| 中文描述： | 400毫安，1.25 MHz的，高效率，降壓型轉換器薄，SOT23封裝 |
| 文件頁數： | 10/20頁 |
| 文件大小： | 464K |
| 代理商： | TPS62228DDC |
www.ti.com
DETAILED DESCRIPTION
OPERATION
The TPS6222x is a synchronous step-down converter operating with typically 1.25-MHz fixed frequency pulse
width modulation (PWM) at moderate to heavy load currents and in power-save mode operating with pulse
frequency modulation (PFM) at light load currents.
POWER-SAVE MODE OPERATION
As the load current decreases, the converter enters the power-save mode operation. During power-save mode,
the converter operates with reduced switching frequency in PFM mode and with a minimum quiescent current to
maintain high efficiency. Two conditions allow the converter to enter the power-save mode operation. One is
when the converter detects discontinuous conduction mode. The other is when the peak switch current in the
P-channel switch goes below the skip current limit. The typical skip current limit can be calculated as
Iskip
66 mA
Vin
160
Ipeak
66 mA
Vin
80
TPS62220, TPS62221, TPS62222
TPS62223, TPS62224
TPS62228, TPS62229
SLVS491C–SEPTEMBER 2003–REVISED SEPTEMBER 2004
During PWM operation, the converter uses a unique fast response, voltage mode, controller scheme with input
voltage feed forward. This achieves good line and load regulation and allows the use of small ceramic input and
output capacitors. At the beginning of each clock cycle initiated by the clock signal (S), the P-channel MOSFET
switch is turned on, and the inductor current ramps up until the comparator trips and the control logic turns off the
switch. The current limit comparator also turns off the switch in case the current limit of the P-channel switch is
exceeded. Then, the N-channel rectifier switch is turned on and the inductor current ramps down. The next cycle
is initiated by the clock signal, again turning off the N-channel rectifier and turning on the P-channel switch.
The GM amplifier and input voltage determines the rise time of the sawtooth generator; therefore, any change in
input voltage or output voltage directly controls the duty cycle of the converter. This gives a very good line and
load transient regulation.
During the power-save mode, the output voltage is monitored with the comparator (comp) by the thresholds
comp low and comp high. As the output voltage falls below the comp low threshold set to 0.8% typical above
Vout, the P-channel switch turns on. The P-channel switch is turned off as the peak switch current is reached.
The typical peak switch current can be calculated:
The N-channel rectifier is turned on and the inductor current ramps down. As the inductor current approaches
zero, the N-channel rectifier is turned off and the P-channel switch is turned on again, starting the next pulse.
The converter continues these pulses until the comp high threshold (set to typically 1.6% above Vout) is reached.
The converter enters a sleep mode, reducing the quiescent current to a minimum. The converter wakes up again
as the output voltage falls below the comp low threshold. This control method reduces the quiescent current
typically to 15 μA and reduces the switching frequency to a minimum, thereby achieving high converter efficiency
at light load. Setting the skip current thresholds to typically 0.8% and 1.6% above the nominal output voltage at
light load current results in a dynamic output voltage achieving lower absolute voltage drops during heavy load
transient changes. This allows the converter to operate with a small output capacitor of just 10 μF and still have a
low absolute voltage drop during heavy load transient changes. See Figure 14 for detailed operation of the
power-save mode.
10
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TPS62228DDCR | 功能描述:直流/直流開關調節器 1.875V Out 400mA Step-Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS62228DDCRG4 | 功能描述:直流/直流開關調節器 1.875V Out 400mA Step-Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS62228DDCT | 功能描述:直流/直流開關調節器 1.875V Out 400mA Step-Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS62228DDCTG4 | 功能描述:直流/直流開關調節器 1.875V Out 400mA Step-Down Converter RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| TPS62229DDCR | 功能描述:開關變換器、穩壓器與控制器 1.7V Out 400mA Step-Down Converter RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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