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參數(shù)資料
| 型號： | TPS51427RHBT |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, PQCC32 |
| 封裝： | 5 X 5 MM, GREEN, PLASTIC, QFN-32 |
| 文件頁數(shù)： | 5/41頁 |
| 文件大?。?/td> | 2040K |
| 代理商： | TPS51427RHBT |
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OUT-OF-AUDIO (OOA) OPERATION
RAMP COMPENSATION
LOW-SIDE DRIVER
HIGH-SIDE DRIVER
BOOSTRAP CHARGE AUTO REFRESH
PWM FREQUENCY AND ADAPTIVE ON-TIME CONTROL
www.ti.com................................................................................................................................................ SLUS819B – APRIL 2008 – REVISED SEPTEMBER 2008
Table 1. SKIPSEL Operating Modes
SKIPSEL
GND
FLOAT/VREF2
V5IN
Operating Mode
Auto Skip
OOA
PWM Only
If out-of-audio (OOA) operation is enabled, the switching frequency of the channel remains higher than the
audible frequency under any load condition, at a minimum of 22 kHz to minimize the audible noise in the system.
The TPS51427 automatically reduces switching frequencies under light load conditions. The OOA control circuit
monitors the switching period and forces the high-side MOSFET to turn on if the switching frequency goes below
the 22-kHz threshold.
The high-side MOSFET turns on even if the output voltage is higher than the target value; therefore, the output
voltage tends to be higher when operating in OOA mode. The OOA control circuit detects the overvoltage
condition and prevents the voltage from rising by re-modulating the device on time. The overvoltage condition is
detected by the VFB1/VOUT2 voltages.
The inductor current ripple (peak-to-peak) should be less than two-thirds of the OCL setting for the OOA circuit to
work properly at a 0-A load. To keep the OOA mode loop stable, the output voltage ripple cannot be too large. If
OOA mode operation is desired, the recommended output ripple voltage cannot be more than 1% of the target
dc voltage.
The TPS51427 employs an advanced ramp compensation technique in D-CAP mode to optimize jitter
performance. An internal ramp signal is added to the reference voltage to virtually increase the slope of the
VFB1/VOUT2 down ramp, which the PWM comparator uses to determine the turn-on timing.
The low-side driver is designed to drive high-current, low RDS(on), N-channel MOSFET(s). The drive capability is
represented by its internal resistance: 1.2
for V5DRV to DRVLx and 0.6 for DRVLx to PGND. A dead time to
prevent shoot-through is generated internally between the two transistors, with the top MOSFET off and bottom
MOSFET on, and then with the bottom MOSFET off and the top MOSFET on. A 5-V bias voltage is delivered
from the V5DRV supply. The instantaneous drive current is supplied by an input capacitor connected between
V5DRV and GND. The average drive current is equal to the gate charge at VGS = 5 V times the switching
frequency.
The high-side driver is also designed to drive high-current, low RDS(on), N-channel MOSFET(s). When configured
as a floating driver, a 5-V bias voltage is delivered from the V5DRV supply. The average drive current is also
calculated by the gate charge at VGS = 5 V times the switching frequency. The instantaneous drive current is
supplied by the floating capacitor between the VBSTx and LLx pins. The drive capability is represented by its
internal resistance: 1.0
for VBSTx to DRVHx and 0.8 for DRVHx to LLx.
Boost undervoltage protection is activated during the device ON time when the voltage difference between
DRVH and LL becomes less than 1.8 V. Upon detection of the undervoltage condition, the high-side gate driver
immediately turns off and the low-side gate driver turns on after the deadtime expires for the minimum off time in
an attempt to recharge the boost capacitor.
The TPS51427 employs an adaptive on-time control scheme and does not have a dedicated onboard oscillator.
However, the device runs with pseudo-constant frequency by feed-forwarding the input voltage and output
voltage into the on-time one-shot timer. The frequencies are set by the TONSEL terminal connection as Table 2
shows. The on-time is controlled: it is inversely proportional to the input voltage and proportional to the output
voltage, so that the duty ratio maintains technically as VOUT/VIN with the same cycle time. Although the
TPS51427 does not use VIN directly, the input voltage is monitored at the LLx pin during the ON state.
Copyright 2008, Texas Instruments Incorporated
13
Product Folder Link(s): TPS51427
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| TPS51427RHBTG4 | 功能描述:DC/DC 開關(guān)控制器 Dual D-Cap Sync Step Down Cntrlr RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(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 |
| TPS51461 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:3.3-V/5-V Input, 6-A, D-CAP+? Mode Synchronous Step-Down Integrated FETs Converter |
| TPS51461RGER | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 3.3-5Vin,6A,D-CAP Mode Sync Step-Down RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| TPS51461RGET | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 3.3-5Vin,6A,D-CAP Mode Sync Step-Down RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| TPS51462 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:3.3-V/5-V Input, D-CAPa?￠ Mode Synchronous Step-Down Integrated FETs Converter With 2-Bit VID |
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