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| 型号： | MAX8660ETL+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 39/44页 |
| 文件大小： | 0K |
| 描述： | IC POWER MANAGE XSCALE 40-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 应用： | 处理器 |
| 电源电压： | 2.6 V ~ 6 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 40-WFQFN 裸露焊盘 |
| 供应商设备封装： | 40-TQFN-EP（5x5） |
| 包装： | 管件 |
| 产品目录页面： | 1411 (CN2011-ZH PDF) |
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High-Efficiency, Low-I Q , PMICs with Dynamic
Voltage Management for Mobile Applications
inductance values than L IDEAL can be used to obtain
higher output current, but typically require physically
Output ripple due to capacitance (neglecting ESR) is
approximately:
larger inductor size. Refer to the MAX8660 EV kit data
sheet for specific inductor recommendations.
Input Capacitor Selection
V RIPPLE =
I L ( PEAK )
2 π x f OSC xC OUT
The input capacitor in a step-down DC-DC converter
reduces current peaks drawn from the battery or other
input power source and reduces switching noise in the
controller. The impedance of the input capacitor at the
switching frequency should be less than that of the
input source so that high-frequency switching currents
do not pass through the input source.
The input capacitor must meet the input-ripple-current
requirement imposed by the step-down converter.
Ceramic capacitors are preferred due to their resilience
to power-up surge currents. Choose the input capacitor
so that the temperature rise due to input ripple current
does not exceed approximately 10°C. For a step-down
DC-DC converter, the maximum input ripple current is
1/2 of the output. This maximum input ripple current
occurs when the step-down converter operates at 50%
duty factor (V IN = 2 x V OUT ).
Refer to the MAX8660 EV kit data sheet for specific
input capacitor recommendations.
Output Capacitor Selection
The step-down DC-DC converter output capacitor
keeps output ripple small and ensures control-loop sta-
bility. The output capacitor must also have low imped-
ance at the switching frequency. Ceramic, polymer,
and tantalum capacitors are suitable, with ceramic
exhibiting the lowest ESR and lowest high-frequency
impedance.
Additional ripple due to capacitor ESR is:
V RIPPLE(ESR) = I L(PEAK) x ESR
Refer to the MAX8660 EV kit data sheet for specific out-
put capacitor recommendations.
Step-Down Converter Output Current
The maximum output current for each step-down con-
verter is listed in the Electrical Characteristics table.
This current is guaranteed by correlation to the p-chan-
nel current-limit threshold, p-channel on-resistance, n-
channel on-resistance, oscillator frequency, input
voltage range, and output voltage range. The maximum
output current in the Electrical Characteristics table is
for the components shown in Figure 3 over then entire
specified range of input and output voltage. For differ-
ent components or voltage ranges, the maximum out-
put current changes. Typically, inductors with a higher
inductance increase the maximum output current, but
they are physically larger and decrease the output volt-
age response time due to a load transient.
Calculate the maximum output current for a particular
application using following the two-step process (see
Figure 12). Use the maximum expected value for input
voltage (V IN ). Using the minimum expected values for
the p-channel current-limit (I LIM ), oscillator frequency
(f), and inductance (L) provides the absolute worst-
case maximum output current (i.e., the lowest value).
TO FIND THE ABSOLUTE WORST - CASE MAXIMUM OUTPU T CURRENT FOR REG 3 WITH V IN = 3 . 2 V TO 4 . 2 V ,
V OUT = 1 . 2 V , L = 1 . 2 μ H ± 30 %, AND R L = 50 m ?
D = OUT OUTTAR N L =
V + I (R + R )
V IN + I OUTTAR ( R N ? R P )
1.2 V + 1.6 A(0.08 ? + 0.05 ? )
4 . 2 V + 1 . 6 A ( 0 . 08 ? ? 0 . 12 ? )
= 0 . 34
I L IM ? OUT
1 + ( R N + R L )
1 . 85 A ?
1 + ( 0 . 08 ? + 0 . 05 ? )
I OUTMAX =
V ( 1 ? D )
2 × f × L
1 ? D
2 × f × L
=
1 . 2 V ( 1 ? 0 . 34 )
2 × ( 1 . 9 × 10 6 Hz ) × ( 1 . 2 × 10 ? 6 H × 0 . 7 )
1 ? 0 . 34
2 × ( 1 . 9 × 10 6 Hz ) × ( 1 . 2 × 10 ? 6 H × 0 . 7 )
= 1 . 56 A
Figure 12. Step-Down Converter Maximum Output Current Example
39
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8660ETL/V+ | 功能描述:PMIC 解决方案 Low-IQ PMIC w/Dynamic V Mgt RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8660ETL/V+T | 功能描述:PMIC 解决方案 Low-IQ PMIC w/Dynamic V Mgt RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8660ETL+ | 功能描述:PMIC 解决方案 Low-IQ PMIC w/Dynamic V Mgt RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8660ETL+T | 功能描述:PMIC 解决方案 Low-IQ PMIC w/Dynamic V Mgt RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
| MAX8660EVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX8660 EVAL KIT/EVAL SYS - Rail/Tube |
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