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参数资料
| 型号： | PTN78020AAH |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 电源模块 |
| 英文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 封装： | ROHS COMPLIANT |
| 文件页数： | 6/20页 |
| 文件大小： | 1237K |
| 代理商： | PTN78020AAH |
www.ti.com
Optional Input/Output Filters
Input/Output Capacitors
C4
100 F
(Required)
#
m
C3*
4 x 4.7 F
Ceramic
(Required)
m
C2
100 F
Electrolytic
m
C1
1 F
50 V
m
R
SET
C5
1 F
Ceramic
m
GND
PTN78020A
4
1, 7
2
V
I
V
I
V
O
V
O
GND
6
Adjust
* See the specifications for required value and type.
# See the
for suggested value and type.
Application Information
π Filters
PTN78020A
SLTS244A – APRIL 2005 – REVISED MAY 2005
Power modules include internal input and output ceramic capacitors in all of their designs. However, some
applications require much lower levels of either input reflected or output ripple/noise. This application describes
various filters and design techniques found to be successful in reducing both input and output ripple/noise.
The easiest way to reduce output ripple and noise is to add one or more 1-F ceramic capacitors, such as C5
shown in Figure 19. Ceramic capacitors should be placed close to the output power terminals. A single 1-F
capacitor reduces the output ripple/noise by 10% to 30% for modules with a rated output current of less than 3 A.
(Note: C4 is required to improve the regulator transient response, and does not reduce output ripple and noise.)
Switching regulators draw current from the input line in pulses at their operating frequency. The amount of
reflected (input) ripple/noise generated is directly proportional to the equivalent source impedance of the power
source including the impedance of any input lines. The addition of C1, minimum 1-F ceramic capacitor, near the
input power pins, reduces reflected conducted ripple/noise by 10% to 30%.
Figure 19. Adding High-Frequency Bypass Capacitors to the Input and Output
If a further reduction in ripple/noise level is required for an application, higher order filters must be used. A
π (pi)
filter, employing a ferrite bead (Fair-Rite Pt. No. 2673000701 or equivalent) in series with the input or output
terminals of the regulator reduces the ripple/noise by at least 20 db (see Figure 20 and Figure 21). In order for
the inductor to be effective in reduction of ripple and noise-ceramic capacitors are required. (See Capacitor
Recommendations for the PTN78020A for additional information on vendors and component suggestions.)
These inductors plus ceramic capacitors form an excellent filter because of the rejection at the switching
frequency (650 kHz - 1 MHz). The placement of this filter is critical. It must be located as close as possible to the
input or output pins to be effective. The ferrite bead is small (12,5 mm × 3 mm), easy to use, low cost, and has
low dc resistance. Fair-Rite also manufactures a surface-mount bead (part number 2773021447), through hole
(part number 2673000701) rated to 5 A. 1-H to 5-H inductors can be used in place of the ferrite inductor bead.
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| PTN78020AAS | 功能描述:DC/DC转换器 4A Wide Inp/Neg Out Adj Module RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
| PTN78020AAST | 功能描述:DC/DC转换器 4A Wide Inp/Neg Out Adj Module RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
| PTN78020AAZ | 功能描述:DC/DC转换器 4A Wide Inp/Neg Out Adj Module RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
| PTN78020AAZT | 功能描述:DC/DC转换器 4A Wide Inp/Neg Out Adj Module RoHS:否 制造商:Murata 产品: 输出功率: 输入电压范围:3.6 V to 5.5 V 输入电压（标称）: 输出端数量:1 输出电压（通道 1）:3.3 V 输出电流（通道 1）:600 mA 输出电压（通道 2）: 输出电流（通道 2）: 安装风格:SMD/SMT 封装 / 箱体尺寸: |
| PTN78020H | 制造商:TI 制造商全称:Texas Instruments 功能描述:6-A, WIDE-INPUT ADJUSTABLE SWITCHING REGULATOR |
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