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参数资料
| 型号： | TPS54350PWP |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 稳压器 |
| 英文描述： | 6.5 A SWITCHING REGULATOR, 700 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封装： | GREEN, PLASTIC, HTSSOP-16 |
| 文件页数： | 8/32页 |
| 文件大小： | 762K |
| 代理商： | TPS54350PWP |
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TPS54350
SLVS456C OCTOBER 2003 REVISED OCTOBER 2004
www.ti.com
16
10
F. A high quality ceramic type X5R or X7R is
recommended. The voltage rating should be greater than
the maximum input voltage. Additionally some bulk
capacitance may be needed, especially if the TPS54350
circuit is not located within about 2 inches from the input
voltage source. The value for this capacitor is not critical
but it also should be rated to handle the maximum input
voltage including ripple voltage and should filter the output
so that input ripple voltage is acceptable.
This input ripple voltage can be approximated by equation
9:
DV
IN +
I
OUT(MAX)
0.25
CBULK
sw
) I
OUT(MAX)
ESR
MAX
Where IOUT(MAX) is the maximum load current, SW is the
switching frequency, CBULK is the bulk capacitor value and
ESRMAX is the maximum series resistance of the bulk
capacitor.
The maximum RMS ripple current also needs to be
checked. For worst case conditions, this can be
approximated by equation 10:
I
CIN +
I
OUT(MAX)
2
In this case the input ripple voltage would be 140 mV and
the RMS ripple current would be 1.5 A. The maximum
voltage across the input capacitors would be VIN max plus
delta VIN/2. The chosen bulk and bypass capacitors are
each rated for 25 V and the combined ripple current
capacity is greater than 3 A, both providing ample margin.
It is very important that the maximum ratings for voltage
and current are not exceeded under any circumstance.
OUTPUT FILTER COMPONENTS
Two components need to be selected for the output filter,
L1 and C2. Since the TPS54350 is an externally
compensated device, a wide range of filter component
types and values can be supported.
Inductor Selection
To calculate the minimum value of the output inductor, use
equation 11:
L
MIN +
V
OUT(MAX)
V
IN(MAX) *
V
OUT
V
IN(max)
K
IND
I
OUT
F
SW
KIND is a coefficient that represents the amount of inductor
ripple current relative to the maximum output current. For
designs using low ESR output capacitors such as
ceramics, use KIND = 0.3. When using higher ESR output
capacitors, KIND = 0.2 yields better results.
For this design example use KIND = 0.2 and the minimum
inductor value is calculated to be 8.98
H. The next highest
standard value is 10
H, which is used in this design.
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 12:
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
(13)
and the peak inductor current can be determined with
equation 13:
(14)
I
L(PK) +
I
OUT(MAX) )
V
OUT
V
IN(MAX) *
V
OUT
1.6
V
IN(MAX)
L
OUT
F
SW
For this design, the RMS inductor current is 3.01 A and the
peak inductor current is 3.34 A. The chosen inductor is a
Vishay IHLP5050CE-01 10
H. It has a saturation current
rating of 14 A and a RMS current rating of 7 A, easily
meeting these requirements. A lesser rated inductor could
be used, however this device was chosen because of its
low profile component height. In general, inductor values
for use with the TPS54350 are in the range of 6.8
H to
47
H.
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 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. In general, it is
desirable to keep the closed loop crossover frequency at
less than 1/5 of the switching frequency. With high
switching frequencies such as the 500-kHz frequency of
this design, internal circuit limitations of the TPS54350
limit the practical maximum crossover frequency to about
50 kHz. Additionally, to allow for adequate phase gain in
the compensation network, the LC corner frequency
should be about one decade or so below the closed loop
crossover frequency. This limits the minimum capacitor
value for the output filter to:
C
OUT +
1
L
OUT
( K
2
p
CO
) 2
Where K is the frequency multiplier for the spread between
fLC and fCO. K should be between 5 and 15, typically 10 for
one decade difference.For a desired crossover of 50 kHz
and a 10-
H inductor, the minimum value for the output
capacitor is 100
F. The selected output capacitor must be
(10)
(11)
(12)
(15)
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PDF描述 |
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| TPS54356PWPG4 | 6.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS54356PWPR | 6.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO16 |
| TPS54354PWPRG4 | 6.5 A SWITCHING REGULATOR, 600 kHz SWITCHING FREQ-MAX, PDSO16 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| TPS54350PWP | 制造商:Texas Instruments 功能描述:IC's |
| TPS54350PWPG4 | 功能描述:直流/直流开关调节器 4.5 to 20V Inp 3A Step-Down Converter RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| TPS54350PWPR | 功能描述:开关变换器、稳压器与控制器 4.5 to 20V Inp 3A Step-Down Converter 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 |
| TPS54350PWPRG4 | 功能描述:开关变换器、稳压器与控制器 4.5 to 20V Inp 3A Step-Down Converter 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 |
| TPS54352 | 制造商:TI 制造商全称:Texas Instruments 功能描述:4.5V TO 20 V INPUT 3-A OUTPUT SYNCHRONOUS PWM SWITCHER WITH INTEGRATED FET |
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