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参数资料
| 型号： | L7981ATR |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, DSO8 |
| 封装： | 3 X 3 MM, 1.08 MM HEIGHT, ROHS COMPLIANT, HSOP-8 |
| 文件页数： | 8/44页 |
| 文件大小： | 1315K |
| 代理商： | L7981ATR |
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Application informations
L7981
16/44
Doc ID 15182 Rev 3
Given the physical dimension, ceramic capacitors can meet well the requirements of the
input filter sustaining an higher input RMS current than electrolytic / tantalum types. In this
case the equation of CIN as a function of the target VPP can be written as follows:
Equation 7
neglecting the small ESR of ceramic capacitors.
Considering
η=1, this function has its maximum in D=0.5, thus, given the maximum peak to
peak input voltage (VPP_MAX), the minimum input capacitor (CIN_MIN) value is:
Equation 8
Typically CIN is dimensioned to keep the maximum peak-peak voltage in the order of 1% of
VINMAX
In
Table 6. some multi layer ceramic capacitors suitable for this device are reported
A ceramic bypass capacitor, as close to the VCC and GND pins as possible, so that
additional parasitic ESR and ESL are minimized, is suggested in order to prevent instability
on the output voltage due to noise. The value of the bypass capacitor can go from 100 nF to
1 F.
6.2
Inductor selection
The inductance value fixes the current ripple flowing through the output capacitor. So the
minimum inductance value in order to have the expected current ripple has to be selected.
The rule to fix the current ripple value is to have a ripple at 20%-40% of the output current.
In the continuos current mode (CCM), the inductance value can be calculated by the
following equation:
Table 6.
Input MLCC capacitors
Manufacture
Series
Cap value (
μF)
Rated voltage (V)
Taiyo Yuden
UMK325BJ106MM-T
10
50
GMK325BJ106MN-T
10
35
Murata
GRM32ER71H475K
4.7
50
C
IN
I
O
V
PP
F
SW
---------------------------
1
D
η
----
–
D
η
----
1D
–
()
+
=
C
IN_MIN
I
O
2V
PP_MAX
F
SW
------------------------------------------------
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| L7981ATR/BLK | 制造商:STMicroelectronics 功能描述:3 A STEP-DOWN SWITCHING REGULATO - Tape and Reel 制造商:STMicroelectronics 功能描述:STMicroelectronics L7981ATR/BLK Interface Misc |
| L7981TR | 功能描述:直流/直流开关调节器 3A DC 4.5 V to 28 V Adj 0.6V 250 kHz 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 |
| L7983 | 制造商:Leviton Manufacturing Co 功能描述: |
| L7985 | 功能描述:线性稳压器 - 标准 2A Step Down REG 4.5V to 38V 250 KHz RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L |
| L7985A | 功能描述:直流/直流开关调节器 2A DC 4.5V to 38V 250 KHz Step-Down 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 |
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