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| 型号： | MAX1820XEUB+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/18页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK WCDMA 10-MSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 转换器，WCDMA 功率放大器应用 |
| 输入电压： | 2.6 V ~ 5.5 V |
| 输出数： | 1 |
| 输出电压： | 0.4 V ~ 3.4 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 10-µMAX |
| 包装： | 带卷 (TR) |
WCDMA Cellular Phone 600mA
Buck Regulators
Table 1. Suggested Inductors
MANUFACTURER
Coilcraft
Coilcraft
Sumida
Sumida
Sumida
PART NUMBER
DO1606
LPT1606-472
CDRH4D18-4R7
CR43
CDRH5D18-4R1
INDUCTANCE
(μH)
4.7
4.7
4.7
4.7
4.1
ESR (m ? )
120
240 (max)
125
108.7
57
SATURATION
CURRENT (A)
1.2
1.2
0.84
1.15
1.95
DIMENSIONS
(mm)
5.3 ? 5.3 ? 2.0
6.5 ? 5.3 ? 2.0
5 ? 5 ? 2
4.5 ? 4.0 ? 3.5
5.5 ? 5.5 ? 2.0
3) Calculate the equivalent load impedance, R L , by:
For most designs, a reasonable inductor value (L IDEAL )
can be derived from the following equation:
RL ≈
V OUT(MAX)
I OUT(MAX)
4) Calculate the compensation resistance (R C ) value to
L IDEAL =
V OUT (V BATT - V OUT )
V BATT × LIR × I OUT(MAX) ×? OSC
cancel out the dominant pole created by the output
load and the output capacitance:
where LIR is the inductor current ripple as a percentage.
LIR should be kept between 20% and 40% of the maxi-
mum load current for best performance and stability.
I L(MAX) = ? 1 +
? I OUT(MAX)
1
2 × π × R L × C OUT
Solving for R C gives:
=
1
2 × π × R C × C1
The maximum inductor current is:
? LIR ?
? 2 ?
= ?
? = 80.8k ?
? 0.6A ? ? 330 pF ?
RC =
R L × C OUT
C1
? 3.4V ? ? 4.7 μ F ?
? ?
The inductor current becomes discontinuous if I OUT
decreases to LIR/2 from the output current value used
to determine L IDEAL .
5) Calculate the high-frequency compensation pole to
cancel the zero created by the output capacitor’s
equivalent series resistance (ESR):
Input Capacitor Selection
The input capacitor reduces the current peaks drawn
from the battery or input power source and reduces
1
2 × π × R ESR × C OUT
=
1
2 × π × R 3 × C 2
`
switching noise in the IC. The impedance of the input
capacitor at the switching frequency should be less
than that of the input source so high-frequency switch-
R ESR × C OUT 4.7 μ F × 0 . 01 ?
80 . 8 k ?
??
I RMS = I LOAD ?
?
?
Solving for C2 gives:
C 2 = = = 0 . 55 pF
R 3
In this case, C2 can be omitted due to the use of
ceramic capacitors. Larger output capacitors and high-
er ESR may require the use of capacitor C2.
Inductor Selection
A 4μH to 6μH inductor with a saturation current of at
least 800mA is recommended for most applications.
For best efficiency, the inductor’s DC resistance should
be <200m ? , and saturation current should be >1A. See
Table 1 for recommended inductors and manufacturers.
ing currents do not pass through the input source.
The input capacitor must meet the ripple-current
requirement (I RMS ) imposed by the switching currents.
Nontantalum chemistries (ceramic, POSCAP, or OS-
CON) are preferred due to their resistance to power-up
surge currents:
? V OUT (V BATT - V OUT ) ?
? V BATT
For optimal circuit reliability, choose a capacitor that
has less than 10°C temperature rise at the peak ripple
current.
14
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| MAX1820YEBC+ | 制造商:Maxim Integrated Products 功能描述:CONV DC-DC SGL-OUT STEP DOWN 12UCSP - Rail/Tube |
| MAX1820YEBC+T | 制造商:Maxim Integrated Products 功能描述:CONV DC-DC SGL-OUT STEP DOWN 12UCSP - Tape and Reel |
| MAX1820YEBC-T | 功能描述:直流/直流开关调节器 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 |
| MAX1820YEUB | 功能描述:直流/直流开关调节器 WCDMA 600mA Buck Regulator 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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