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參數資料
| 型號： | TPS51315RGFT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩壓器 |
| 英文描述： | SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PQCC40 |
| 封裝： | GREEN, PLASTIC, QFN-40 |
| 文件頁數： | 2/32頁 |
| 文件大小： | 1028K |
| 代理商： | TPS51315RGFT |
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( )
12
OUT
ON
T on
IN
(2 / 3)V
100mV
T
19 10
R
50ns
V
-
+
=
+
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SLUS881A
– MAY 2009 – REVISED MAY 2011
PWM Frequency and Adaptive On Time Control
TPS51315 employs an adaptive on-time control scheme and does not include a dedicated oscillator on the
device. However, the device runs with pseudo-constant frequency by feed-forwarding the input voltage and
output voltage to the on-time, one-shot timer. The on-time control is inversely proportional to the input voltage
and proportional to the output voltage, so that the duty ratio is maintained as VOUT/VIN with the same cycle time,
as shown in Equation 3.
where
RT(on)x is the external resistor connected from TON to LL
(3)
For the TPS51315, the input voltage is monitored at the LL pin during the ON state. An advantage of
switching-node monitoring is that any loss in the high-side n-channel FET becomes part of the on-time
calculation, thereby making the frequency more stable with load.
Another consideration regarding frequency is jitter. Jitter may have many causes, but the constant on-time
D-CAP mode scheme has some amount of inherent jitter. Because the output voltage ripple height is in the
range of approximately 20 mV, on the order of a milli-volt of noise on the feedback signal can affect the
frequency between approximately 3% and 10%. This is normal operation and risks only a small amount of
influence to the power supply performance.
Soft-Start
The TPS51315 includes an independent, internal, 1.06-ms, voltage servo soft-start function with overcurrent limit.
When the EN_PSV pin goes high, an internal digita-to-analog converter (DAC) begins ramping up the reference
voltage to the error amplifier. Smooth control of the output voltage is maintained during start-up.
Powergood
The TPS51315 includes a powergood output function. The powergood function is activated after the soft-start
function has completed. If the output voltage comes within
±5% of the target value, internal comparators detect a
powergood state and the powergood signal becomes high after a 64-
μs internal delay. If the output voltage rises
above or falls below 10% of the target value, the powergood signal goes low immediately.
Output Discharge Control
The TPS51315 discharges output when EN_PSV is low or when the channel is in either a UVP or OVP fault
condition. The TPS51315 discharges output using an internal 20-
MOSFET that is connected to VOUT_DS and
PGND. The current capability of the MOSFET is limited to discharge slowly. An external resistor can be
connected between VOUT_DS and VOUT to program discharge slow rate. In case the discharge function is not
wanted, leave VOUT_DS open.
10
Copyright
2009–2011, Texas Instruments Incorporated
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| TPS51317RGBR | 功能描述:直流/直流開關轉換器 3.3V/5Vin,6A,DCAP Mode Sync Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| TPS51317RGBT | 功能描述:直流/直流開關轉換器 3.3V/5Vin,6A,DCAP Mode Sync Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數量:2 最大工作溫度:+ 85 C 安裝風格:SMD/SMT |
| TPS51362RVER | 制造商:Texas Instruments 功能描述:22V INPUT, 10A INTEGRATED FET 制造商:Texas Instruments 功能描述:IC REG BUCK SYNC ADJ 10A 28VQFN |
| TPS51362RVET | 制造商:Texas Instruments 功能描述:22V INPUT, 10A INTEGRATED FET 制造商:Texas Instruments 功能描述:IC REG BUCK SYNC ADJ 10A 28VQFN |
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