參數(shù)資料
型號(hào): TPS5420D
廠商: TEXAS INSTRUMENTS INC
元件分類: 穩(wěn)壓器
英文描述: 6.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO8
封裝: PLASTIC, MS-012AA, SOIC-8
文件頁數(shù): 4/24頁
文件大?。?/td> 738K
代理商: TPS5420D
www.ti.com
LMIN =
()
VOUT
IN(MAX)
OUT
xV
-V
VIN(max)
IND
OUT
SW
xK
xI
xF
x0.8
(4)
I
L(RMS) +
I2
OUT(MAX) )
1
12
V
OUT
V
IN(MAX) *
V
OUT
V
IN(MAX)
L
OUT
F
SW
0.8
2
(5)
IL(PK) =I
+
OUT(MAX)
()
V
OUT
IN(MAX)
OUT
x
-
1.6 xV
xL
xF
IN(MAX)
OUT
SW
(6)
SLVS642C – APRIL 2006 – REVISED OCTOBER 2007
CAUTION:
The maximum ratings for voltage and current are not to be exceeded under any
circumstance.
Additionally, some bulk capacitance may be needed, especially if the TPS5420 circuit is not located within
approximately 2 inches from the input voltage source. The value for this capacitor is not critical but it should be
rated to handle the maximum input voltage including ripple voltage and should filter the output so that input ripple
voltage is acceptable.
Output Filter Components
Two components need to be selected for the output filter, L1 and C2. Since the TPS5420 is an internally
compensated device, a limited range of filter component types and values can be supported.
Inductor Selection
To calculate the minimum value of the output inductor, use Equation 4:
KIND is a coefficient that represents the amount of inductor ripple current relative to the maximum output current.
Three things need to be considered when determining the amount of ripple current in the inductor: the peak to
peak ripple current affects the output ripple voltage amplitude, the ripple current affects the peak switch current,
and the amount of ripple current determines at what point the circuit becomes discontinuous. For designs using
the TPS5420, KIND of 0.2 to 0.3 yields good results. Low output ripple voltages is obtained when paired with the
proper output capacitor, the peak switch current is below the current limit set point, and low load currents can be
sourced before discontinuous operation.
For this design example, use KIND = 0.2, and the minimum inductor value is 27 μH. The standard value used in
this design is 33
μH.
For the output filter inductor, it is important that the RMS current and saturation current ratings not be exceeded.
The RMS inductor current can be found from Equation 5:
and the peak inductor current can be determined using Equation 6:
For this design, the RMS inductor current is 2.002 A, and the peak inductor current is 2.16 A. The chosen
inductor is a Coilcraft MSS1260-333 type. The nominal inductance is 33
μH. It has a saturation current rating of
2.2 A and a RMS current rating of 2.7 A, which meets the requirements. Inductor values for use with the
TPS5420 are in the range of 10
μH to 100 μH.
Capacitor Selection
The important design factors for the output capacitor are dc voltage rating, ripple current rating, and equivalent
series resistance (ESR). The dc voltage and ripple current ratings cannot be exceeded. The ESR is important
because along with the inductor ripple current it determines the amount of output ripple voltage. The actual value
of the output capacitor is not critical, but some practical limits do exist. Consider the relationship between the
desired closed loop crossover frequency of the design and LC corner frequency of the output filter. Due to the
12
Copyright 2006–2007, Texas Instruments Incorporated
Product Folder Link(s): TPS5420
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TPS5420D 制造商:Texas Instruments 功能描述:Linear Voltage Regulator IC
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TPS5420D-P 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述:
TPS5420DR 功能描述:直流/直流開關(guān)調(diào)節(jié)器 5.5 to 36V 2A Step Down Swift Conv 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
TPS5420DRG4 功能描述:直流/直流開關(guān)調(diào)節(jié)器 5.5 to 36V 2A Step Down Swift Conv 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