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參數資料
| 型號： | TPS51511RHLT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩壓器 |
| 英文描述： | SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PQCC20 |
| 封裝： | ROHS COMPLIANT, PLASTIC, QFN-20 |
| 文件頁數： | 6/29頁 |
| 文件大小： | 1019K |
| 代理商： | TPS51511RHLT |
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PWM Frequency and Adaptive On-Time Control
Soft-Start and Powergood (PGOOD)
T
VOSW +
2
C
VOSW
V
VOSW
I
VOSWOCP
) 80 ms
(2)
T
VLDO +
C
VLDO
V
VLDO
I
VLDOOCL
(3)
Enable and Discharge
SLVS735A – FEBRUARY 2007 – REVISED APRIL 2007
TPS51511 employs an adaptive on-time control scheme, and does not have a dedicated oscillator on board.
However, the device runs with a fixed 350kHz pseudo-constant frequency by feed-forwarding the input and
output voltage into the on-time one-shot timer. The on-time is inversely proportional to the input voltage and
proportional to the output voltage so that the duty-cycle ratio is kept the same as VOUT/VIN in the same cycle
time. Although the TPS51511 does not have a pin connected to VIN, the input voltage is monitored at the LL pin
during the ON state. This reduces the pin count in order to make the part compact without sacrificing its
performance. In order to secure minimum ON time during startup, the feed-forward feature from the output
voltage is enabled after the output voltage becomes 750 mV or higher.
The soft-start function of the switcher is achieved by ramping up the reference voltage and a two-stage current
clamp. At the starting point, the reference voltage is set to 650 mV (87% of its target value), and the overcurrent
threshold is set to half of the nominal value. When the UVP comparator detects an VOSW voltage greater than
80% of the target, the reference begins to ramp up and reaches 750 mV after 85
s. 45 s after the voltage
becomes good, the power-good comparator releases the overcurrent threshold to the nominal value. TPS51511
turns off the power-good open-drain MOSFET when VOSW reaches the good state.
The soft-start function of the LDO is achieved by clamping the current during startup. The threshold of the
current limit is set to 2.5 A (typical). TPS51511 has an independent window comparator for each output, but the
PGOOD signal indicates only the status of VOSW. If a separate powergood signal is needed for the LDO, see
OD and ODOFF for configuration details.
The soft-start durations, TVOSW, TVLDO are functions of output capacitances.
Where, IVLDOOCL = 2.5 A (typical).
In both equations, no load current during startup is assumed. Note that both the switcher and the LDO do not
start up to target voltage with full load conditions.
Both the switcher and LDO can be enabled by bringing the voltage on the ENSW and ENLDO pins above 2.2 V,
and disabled by pulling the voltage of ENSW and ENLDO down to 0.3 V. Both the switcher and LDO have
output-discharge feature. The output is discharged through an internal MOSFET when the channel is disabled.
Discharge continues until the output voltage is discharged below 0.3 V. In UVP or OVP conditions of the
switching power supply, the device is latched off and the discharge is enabled until the output voltage drops
below 0.3 V.
14
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TPS51511RHLTG4 | 功能描述:DC/DC 開關控制器 Synch Switcher Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| TPS51513 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:SINGLE PHASE D-CAP+ SYNCHRONOUS BUCK CONTROLLER WITH INTEGRATED DRIVERS FOR GENERAL IC VCORE APPLICATIONS |
| TPS51513EVM-549 | 功能描述:電源管理IC開發工具 TPS51513EVM-549 Eval Mod RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| TPS51513EVM-549 | 制造商:Texas Instruments 功能描述:DEVELOPMENT TOOL |
| TPS51513RHB | 制造商:TI 制造商全稱:Texas Instruments 功能描述:SINGLE PHASE D-CAP+ SYNCHRONOUS BUCK CONTROLLER WITH INTEGRATED DRIVERS FOR GENERAL IC VCORE APPLICATIONS |
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