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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： | 9/32页 |
| 文件大小： | 762K |
| 代理商： | TPS54350PWP |
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TPS54350
SLVS456C OCTOBER 2003 REVISED OCTOBER 2004
www.ti.com
17
rated for a voltage greater than the desired output voltage
plus one half the ripple voltage. Any derating amount must
also be included. The maximum RMS ripple current in the
output capacitor is given by equation 15:
I
COUT(RMS) +
1
12
V
OUT
V
IN(MAX) *
V
OUT
V
IN(MAX)
L
OUT
F
SW
N
C (16)
where NC is the number of output capacitors in parallel.
The maximum ESR of the output capacitor is
determined by the amount of allowable output ripple as
specified in the initial design parameters. The output
ripple voltage is the inductor ripple current times the
ESR of the output filter so the maximum specified ESR
as listed in the capacitor data sheet is given by equation
16:
ESR
MAX +
N
C
V
IN(MAX)
L
OUT
F
SW
0.8
V
OUT
V
IN(MAX) *
V
OUT
DV
p
*p(MAX)
Where
nVpp is the desired peak-to-peak output ripple.
For this design example, a single 100-
F output capacitor
is chosen for C2 since the design goal is small size. The
calculated RMS ripple current is 156 mV and the maximum
ESR required is 59 m
. A capacitor that meets these
requirements is a Sanyo Poscap 6TPC100M, rated at
6.3 V with a maximum ESR of 45 m
and a ripple current
rating of 1.7 A. An additional small 0.1-
F ceramic bypass
capacitor is also used.
Other capacitor types work well with the TPS54350,
depending on the needs of the application.
COMPENSATION COMPONENTS
The external compensation used with the TPS54350
allows for a wide range of output filter configurations. A
large range of capacitor values and types of dielectric are
supported. The design example uses type 3 compensation
consisting of R1, R3, R5, C6, C7 and C8. Additionally, R2
along with R1 forms a voltage divider network that sets the
output voltage. These component reference designators
are the same as those used in the SWIFT Designer
Software. There are a number of different ways to design
a compensation network. This procedure outlines a
relatively simple procedure that produces good results
with most output filter combinations. Use of the SWIFT
Designer Software for designs with unusually high closed
loop crossover frequencies, low value, low ESR output
capacitors such as ceramics or if the designer is unsure
about the design procedure is recommended.
When
designing
compensation
networks
for
the
TPS54350, a number of factors need to be considered.
The gain of the compensated error amplifier should not be
limited by the open loop amplifier gain characteristics and
should not produce excessive gain at the switching
frequency. Also, the closed loop crossover frequency
should be set less than one fifth of the switching frequency,
and the phase margin at crossover must be greater than
45 degrees. The general procedure outlined here
produces results consistent with these requirements
without going into great detail about the theory of loop
compensation.
First calculate the output filter LC corner frequency using
equation 17:
LC +
1
2
p L
OUT
C
OUT
For the design example, fLC = 5033 Hz.
The closed loop crossover frequency should be greater
than fLC and less than one fifth of the switching frequency.
Also, the crossover frequency should not exceed 50 kHz,
as the error amplifier may not provide the desired gain. For
this design, a crossover frequency of 30 kHz was chosen.
This value is chosen for comparatively wide loop
bandwidth while still allowing for adequate phase boost to
insure stability.
Next calculate the R2 resistor value for the output voltage
of 3.3 V using equation 18:
R2
+
R1
0.891
V
OUT *
0.891
For any TPS54350 design, start with an R1 value of 1.0 k
.
R2 is then 374
.
Now the values for the compensation components that set
the poles and zeros of the compensation network can be
calculated. Assuming that R1 > R5 and C6 > C7, the pole
and zero locations are given by equations 19 through 22:
Z1 +
1
2
pR3C6
Z2 +
1
2
pR1C8
P1 +
1
2
pR5C8
P2 +
1
2
pR3C7
Additionally there is a pole at the origin, which has unity
gain with the following frequency:
INT +
1
2
pR1C6
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
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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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