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参数资料
| 型号： | MAX8546EVKIT |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/18页 |
| 文件大小： | 0K |
| 描述： | EVAL KIT FOR MAX8546 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 2.5V |
| 电流 - 输出： | 6A |
| 输入电压： | 10 ~ 24V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 300kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MAX8546 |
Low-Cost, Wide Input Range, Step-Down
Controllers with Foldback Current Limit
R 3 = R 4 ? OUT ? 1 ?
from high-voltage inputs. With high input voltages, the
required duty factor is approximately:
V OUT + (R DS( ON) × I LOAD )
V IN
where R DS(ON) x I LOAD is the voltage drop across the
synchronous rectifier. Therefore, the maximum input
voltage (V IN(DFMAX) ) that can supply a given output
voltage is:
Setting the Output Voltage
An output voltage between 0.8V and (0.83 x V IN ) can
be configured by connecting FB to a resistive divider
between the output and GND (see Figures 1 and 2).
Select resistor R4 in the 1k Ω to 10k Ω range. R3 is then
given by:
? V ?
? V FB ?
V IN ( DFMAX ) ≤
1
DC MIN
(
V OUT + ( R DS ( ON ) × I LOAD
) )
where V FB = +0.8V.
Inductor Selection
Determine an appropriate inductor value with the fol-
If the circuit cannot attain the required duty cycle dic-
tated by the input and output voltages, the output volt-
age still remains in regulation. However, there may be
intermittent or continuous half-frequency operation as
lowing equation:
L = V OUT ×
( V IN ? V OUT )
V IN × f OSC × LIR × I LOAD ( MAX )
I PEAK LOAD ( MAX ) + ?
? LIR ?
? 2 ?
the controller attempts to lower the average duty cycle
by deleting pulses. This can increase output voltage
ripple and inductor current ripple, which increases
noise and reduces efficiency. Furthermore, circuit sta-
bility is not guaranteed.
Applications Information
Design Procedures
1) Input Voltage Range . The maximum value
(V IN(MAX) ) must accommodate the worst-case high
input voltage. The minimum value (V IN(MIN) ) must
account for the lowest input voltage after drops due
to connectors, fuses, and switches are considered.
In general, lower input voltages provide the best
efficiency.
2) Maximum Load Current . There are two current
values to consider. Peak load current (I LOAD(MAX) )
determines the instantaneous component stresses
and filtering requirements and is key in determining
output capacitor requirements. I LOAD(MAX) also
determines the required inductor saturation rating.
Continuous load current (I LOAD ) determines the
thermal stresses, input capacitor, and MOSFETs,
as well as the RMS ratings of other heat-contribut-
where LIR is the ratio of inductor ripple current to aver-
age continuous maximum load current. Choosing LIR
between 20% to 40% results in a good compromise
between efficiency and economy. Choose a low-core-
loss inductor with the lowest possible DC resistance.
Ferrite-core-type inductors are often the best choice for
performance; however, the MAX8548’s low switching
frequency also allows the use of powdered iron core
inductors in ultra-low-cost applications where efficiency
is not critical. With any core material, the core must be
large enough not to saturate at the peak inductor cur-
rent (I PEAK ):
= I ? × I LOAD ( MAX )
Setting the Current Limit
The MAX8545/MAX8546/MAX8548 provide valley cur-
rent limit by sensing the voltage across the external
low-side MOSFET. The minimum current-limit threshold
voltage is -280mV for the MAX8545/MAX8548 and
-140mV for the MAX8546. The MOSFET on-resistance
required to allow a given peak inductor current is:
ing components such as the inductor.
3) Inductor Value . This choice provides tradeoffs
between size, transient response, and efficiency.
Higher inductance value results in lower inductor
ripple current, lower peak current, lower switching
losses, and, therefore, higher efficiency at the cost
R DS ( ON ) MAX ≤
R DS ( ON ) MAX ≤
0 . 28 V
I VALLEY
0 . 14 V
I VALLEY
( for the MAX 8545 / MAX 8548 )
( for the MAX 8546 )
of slower transient response and larger size. Lower
inductance values result in large ripple currents,
smaller size, and poor efficiency, while also provid-
ing faster transient response.
where I VALLEY = I LOAD(MAX) x (1 - LIR / 2), and
R DS(ON)MAX is the maximum on-resistance of the low-
side MOSFET at the maximum operating junction
temperature.
_______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8548EUB | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8548EUB+ | 功能描述:电压模式 PWM 控制器 Wide Input Range Step-Down Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX8548EUB+T | 功能描述:电压模式 PWM 控制器 Wide Input Range Step-Down Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX8548EUB-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8550AETI | 功能描述:PMIC 解决方案 RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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