參數(shù)資料
型號(hào)： TPS54418RTER
廠商： TEXAS INSTRUMENTS INC
元件分類： 穩(wěn)壓器
英文描述： 6.4 A SWITCHING REGULATOR, 2000 kHz SWITCHING FREQ-MAX, PQCC16
封裝： 3 X 3 MM, GREEN, PLASTIC, WQFN-16
文件頁(yè)數(shù)： 13/35頁(yè)
文件大?。?/td> 1356K
代理商： TPS54418RTER
-
Vinmax
Vout
L1 =
Io
Kind
Vinmax
sw
-
Vinmax
Vout
Iripple =
L1
Vinmax
sw
-
÷
è
2
1
Vo
(Vinmax
Vo)
ILrms =
Io
+
12
Vinmax
L1
sw
Iripple
ILpeak = Iout +
2
Iout
C o >
sw
Vout
D
D
1
Co >
Voripple
8
sw
Iripple
SLVS946A – MAY 2009 – REVISED MAY 2010
www.ti.com
For this design example, use KIND = 0.3 and the inductor value is calculated to be 0.96 mH. For this design, a
nearest standard value was chosen: 1.0 mH. For the output filter inductor, it is important that the RMS current
and saturation current ratings not be exceeded. The RMS and peak inductor current can be found from
For this design, the RMS inductor current is 4.014 A and the peak inductor current is 4.58 A. The chosen
inductor is a TOKO FDV0630-1R0M. It has a current rating of 9.1 A.
The current flowing through the inductor is the inductor ripple current plus the output current. During power up,
faults or transient load conditions, the inductor current can increase above the calculated peak inductor current
level calculated above. In transient conditions, the inductor current can increase up to the switch current limit of
the device. For this reason, the most conservative approach is to specify an inductor with a saturation current
rating equal to or greater than the switch current limit rather than the peak inductor current.
(18)
(19)
(20)
(21)
OUTPUT CAPACITOR
There are three primary considerations for selecting the value of the output capacitor. The output capacitor
determines the modulator pole, the output voltage ripple, and how the regulator 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 is temporarily not 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 22 shows the minimum output capacitance necessary
to accomplish this.
For this example, the transient load response is specified as a 3% change in Vout for a load step from 1A (25%
load) to 2A (50%). For this example,
ΔIout = 2-1 = 1.0 A and ΔVout= 0.03 × 1.8 = 0.054 V. Using these numbers
gives a minimum capacitance of 37mF. 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.
Equation 23 calculates the minimum output capacitance needed to meet the output voltage ripple specification.
Where fsw is the switching frequency, Vripple is the maximum allowable output voltage ripple, and Iripple is the
inductor ripple current. In this case, the maximum output voltage ripple is 30 mV. Under this requirement,
Equation 23 yields 4.8uF.
(22)
Where
ΔIout is the change in output current, Fsw is the regulators switching frequency and ΔVout is the
allowable change in the output voltage.
(23)
20
Copyright 2009–2010, Texas Instruments Incorporated
Product Folder Link(s): TPS54418
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TPS54418RTERG4 制造商:Texas Instruments 功能描述:
TPS54418RTET 功能描述:直流/直流開關(guān)調(diào)節(jié)器 2.95-6Vin 4A 2MHz Synch St Down RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
TPS54424RNVT 功能描述:4.5V TO 17V INPUT, CURRENT MODE, 制造商:texas instruments 系列:SWIFT?? 包裝:剪切帶（CT） 零件狀態(tài):在售 功能:降壓 輸出配置:正 拓?fù)?降壓 輸出類型:可調(diào)式 輸出數(shù):1 電壓 - 輸入（最小值）:4.5V 電壓 - 輸入（最大值）:17V 電壓 - 輸出（最小值/固定）:0.6V 電壓 - 輸出（最大值）:12V 電流 - 輸出:4A 頻率 - 開關(guān):200kHz ~ 1.6MHz 同步整流器:是 工作溫度:-40°C ~ 150°C（TJ） 安裝類型:表面貼裝 封裝/外殼:18-VFQFN 供應(yīng)商器件封裝:18-VQFN-HR（3.5x3.5） 標(biāo)準(zhǔn)包裝:1
TPS54425 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-A OUTPUT SINGLE SYNCHRONOUS STEP DOWN SWITCHER WITH INTEGRATED FET ( SWIFT?)
TPS54425_10 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-A OUTPUT SINGLE SYNCHRONOUS STEP DOWN SWITCHER WITH INTEGRATED FET ( SWIFT?)
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