参数资料
| 型号： | TPS54260DRCR |
| 厂商： | Texas Instruments |
| 文件页数： | 30/52页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 2.5A 10SON |
| 标准包装： | 3,000 |
| 系列： | SWIFT™, Eco-Mode™ |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 58 V |
| 输入电压： | 3.5 V ~ 60 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 100kHz ~ 2.5MHz |
| 电流 - 输出： | 2.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 150°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-VFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 10-SON 裸露焊盘（3x3） |
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SLVSA86A – MARCH 2010 – REVISED DECEMBER 2010
www.ti.com
I RIPPLE =
V OUT ′ ( Vin max - V OUT )
Vin max ′ L O ′ f SW
(29)
( I O ) 2 + 12 ′ ? ?
1 ? V OUT ′ ( Vinmax - V OUT ) ?
÷
I L(rms) =
è Vinmax ′ L O ′ f SW ?
÷
2
(30)
ILpeak = Iout +
Iripple
2
(31)
Output Capacitor
There are three primary considerations for selecting the value of the output capacitor. The output capacitor will
determine the modulator pole, the output voltage ripple, and how the regulators responds to a large change in
load current. The output capacitance needs to be selected based on the more stringent of these three criteria.
The desired response to a large change in the load current is the first criteria. The output capacitor needs to
supply the load with current when the regulator can not. This situation would occur if there are desired hold-up
times for the regulator where the output capacitor must hold the output voltage above a certain level for a
specified amount of time after the input power is removed. The regulator also will temporarily not be able to
supply sufficient output current if there is a large, fast increase in the current needs of the load such as
transitioning from no load to a full load. The regulator usually needs two or more clock cycles for the control loop
to see the change in load current and output voltage and adjust the duty cycle to react to the change. The output
capacitor must be sized to supply the extra current to the load until the control loop responds to the load change.
The output capacitance must be large enough to supply the difference in current for 2 clock cycles while only
allowing a tolerable amount of droop in the output voltage. Equation 32 shows the minimum output capacitance
necessary to accomplish this.
Where Δ Iout is the change in output current, ?sw is the regulators switching frequency and Δ Vout is the
allowable change in the output voltage. For this example, the transient load response is specified as a 3%
change in Vout for a load step from 1.5 A to 2.5 A (full load). For this example, Δ Iout = 2.5-1.5 = 1.0 A and Δ Vout
= 0.03 × 3.3 = 0.099 V. Using these numbers gives a minimum capacitance of 67 m F. This value does not take
the ESR of the output capacitor into account in the output voltage change. For ceramic capacitors, the ESR is
usually small enough to ignore in this calculation. Aluminum electrolytic and tantalum capacitors have higher
ESR that should be taken into account.
The catch diode of the regulator can not sink current so any stored energy in the inductor will produce an output
voltage overshoot when the load current rapidly decreases, see Figure 50 . The output capacitor must also be
sized to absorb energy stored in the inductor when transitioning from a high load current to a lower load current.
The excess energy that gets stored in the output capacitor will increase the voltage on the capacitor. The
capacitor must be sized to maintain the desired output voltage during these transient periods. Equation 33 is
used to calculate the minimum capacitance to keep the output voltage overshoot to a desired value. Where L is
the value of the inductor, I OH is the output current under heavy load, I OL is the output under light load, Vf is the
final peak output voltage, and Vi is the initial capacitor voltage. For this example, the worst case load step will be
from 2.5 A to 1.5 A. The output voltage will increase during this load transition and the stated maximum in our
specification is 3 % of the output voltage. This will make Vf = 1.03 × 3.3 = 3.399. Vi is the initial capacitor voltage
which is the nominal output voltage of 3.3 V. Using these numbers in Equation 33 yields a minimum capacitance
of 60 m F.
Equation 34 calculates the minimum output capacitance needed to meet the output voltage ripple specification.
Where fsw is the switching frequency, V oripple is the maximum allowable output voltage ripple, and I ripple is the
inductor ripple current. Equation 34 yields 12 m F.
Equation 35 calculates the maximum ESR an output capacitor can have to meet the output voltage ripple
specification. Equation 35 indicates the ESR should be less than 36 m ? .
The most stringent criteria for the output capacitor is 67 m F of capacitance to keep the output voltage in
regulation during an load transient.
Additional capacitance de-ratings for aging, temperature and dc bias should be factored in which will increase
this minimum value. For this example, 2 x 47 m F, 10 V ceramic capacitors with 3 m ? of ESR will be used. The
derated capacitance is 72.4 μF, above the minimum required capacitance of 67 μF.
30
Product Folder Link(s): TPS54260
Copyright ? 2010, Texas Instruments Incorporated
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| TPS54260DRCT | 功能描述:直流/直流开关转换器 3.5V-60Vin,2.5A,2.5 MHz Step Down SWIFT 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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| TPS54260MDGQTEP | 功能描述:IC REG BUCK ADJ 2.5A 10MOSP 制造商:texas instruments 系列:Eco-Mode? 包装:剪切带（CT） 零件状态:在售 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:3.5V 电压 - 输入（最大值）:60V 电压 - 输出（最小值/固定）:0.8V 电压 - 输出（最大值）:60V 电流 - 输出:2.5A 频率 - 开关:100kHz ~ 2.5MHz 同步整流器:无 工作温度:-40°C ~ 150°C（TJ） 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽）裸露焊盘 供应商器件封装:10-MSOP-PowerPad 标准包装:1 |
| TPS54260MDRCTEP | 功能描述:IC REG BUCK ADJ 2.5A 10VSON 制造商:texas instruments 系列:Eco-Mode? 包装:剪切带（CT） 零件状态:在售 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:3.5V 电压 - 输入（最大值）:60V 电压 - 输出（最小值/固定）:0.8V 电压 - 输出（最大值）:60V 电流 - 输出:2.5A 频率 - 开关:100kHz ~ 2.5MHz 同步整流器:无 工作温度:-40°C ~ 150°C（TJ） 安装类型:表面贴装 封装/外壳:10-VFDFN 裸露焊盘 供应商器件封装:10-VSON（3x3） 标准包装:1 |
| TPS54260-Q1 | 制造商:TI 制造商全称:Texas Instruments 功能描述:3.5 V to 60 V STEP DOWN CONVERTER WITH ECO-MODEa?￠ |
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