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| 型号： | TPS51461RGET |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, 1000 kHz SWITCHING FREQ-MAX, PQCC24 |
| 封装： | 4 X 4 MM, GREEN, PLASTIC, QFN-24 |
| 文件页数： | 8/31页 |
| 文件大小： | 1627K |
| 代理商： | TPS51461RGET |
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SLEW
I
C
SR
=
SLEW
SS
SLEW
C
0.9 V
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SLUSAD9 – DECEMBER 2010
www.ti.com
Light Load Power Saving Features
The TPS51461 has an automatic pulse-skipping mode to provide excellent efficiency over a wide load range.
The converter senses inductor current and prevents negative flow by shutting off the low-side gate driver. This
saves power by eliminating re-circulation of the inductor current. Further, when the bottom FET shuts off, the
converter enters discontinuous mode, and the switching frequency decreases, thus reducing switching losses as
well.
Voltage Slewing
The TPS51461 ramps the SLEW voltage up and down to perform the output voltage transitioning. The timing is
independent of switching frequency, as well as output resistive and capacitive loading. It is set by a capacitor
from SLEW pin to GND, called CSLEW, together with an internal current source of 10 A. The slew rate is used to
set the startup and voltage transition rate.
(4)
where
ISLEW = 10 A (nom)
SR is the target output voltage slew rate, per Intel specification between 0.5 mV/s and 10 mV/s
(5)
For the current reference design, an SR of 1 mV/s is targeted. The CSLEW is calculated to be 10 nF. The slower
slew rate is desired to minimize large inductor current perturbation during startup and voltage transitioning thus
reducing the possibility of acoustic noise.
After the power up, when VID1 is transitioning from 0 to 1, TPS51461 follows the SLEW voltage entering the
forced PWM mode to actively discharge the output voltage from 0.9 V to 0.8 V. The actual output voltage slew
rate is approximately the same as the set slew rate while the bandwidth of the converter supports it and there is
no overcurrent triggered by additional charging current flowing into the output capacitors. After SLEW transition is
completed, PWM mode is maintained for 64 s (16 clock cycles when the frequency is 1 MHz) to ensure voltage
regulation.
Protection Features
The TPS51461 offers many features to protect the converter power chain as well as the system electronics.
5-V Undervoltage Protection (UVLO)
The TPS51461 continuously monitors the voltage on the V5FILT pin to ensure that the voltage level is high
enough to bias the device properly and to provide sufficient gate drive potential to maintain high efficiency. The
converter starts with approximately 4.3 V and has a nominal of 440 mV of hysteresis. If the 5-V UVLO limit is
reached, the converter transitions the phase node into a 3-state function. And the converter remains in the off
state until the device is reset by cycling 5 V until the 5-V POR is reached (2.3-V nominal). The power input does
not have an UVLO function
Power Good Signals
The TPS51461 has one open-drain power good (PGOOD) pin. During startup, there is a 3 ms power good delay
starting from the output voltage reaching the regulation point (excluding soft-start ramp-up time). And there is
also a 1 ms power good high propagation delay. The PGOOD pin de-asserts as soon as the EN pin is pulled low
or an undervoltage condition on V5FILT is detected. The PGOOD signal is blanked during VID voltage transitions
to prevent false triggering during voltage slewing.
16
Copyright 2010, Texas Instruments Incorporated
Product Folder Link(s): TPS51461
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS51462 | 制造商:TI 制造商全称: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 |
| TPS51462RGER | 功能描述:开关变换器、稳压器与控制器 3.3V/5Vin,DCAP Mode Sync SD Integ FET RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TPS51462RGET | 功能描述:开关变换器、稳压器与控制器 3.3V/5Vin,DCAP Mode Sync SD Integ FET RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| TPS51463 | 制造商:TI 制造商全称:Texas Instruments 功能描述:3.3-V/5-V Input, D-CAP+? Mode Synchronous Step-Down Integrated FETs Converter |
| TPS51463RGER | 功能描述:直流/直流开关转换器 3.3V/5Vin,Sync SD Integr FET Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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