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| 型号： | MAX15026CATD+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 13/23页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 14TDFN |
| 产品培训模块： | Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2.4MHz |
| 占空比： | 88% |
| 电源电压： | 4.5 V ~ 28 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 封装/外壳： | 14-WFDFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
MAX15026
Low-Cost, Small, 4.5V to 28V Wide Operating
Range, DC-DC Synchronous Buck Controller
frequency, input voltage, output voltage, and selected
OUT
LIR determine the inductor value as follows,
L = OUT IN OUT
R 1
V ( V ? V
V IN f SW I OUT LIR
)
FB
where V IN , V OUT , and I OUT are typical values (so that
efficiency is optimum for typical conditions). The switch-
MAX15026
R 2
ing frequency is set by R RT (see the Setting the
Switching Frequency section). The exact inductor value
is not critical and can be adjusted to make trade-offs
among size, cost, and efficiency. Lower inductor values
minimize size and cost, but also improve transient
response and reduce efficiency due to higher peak cur-
rents. On the other hand, higher inductance increases
efficiency by reducing the RMS current.
Figure 2. Adjustable Output Voltage
Setting the Switching Frequency
An external resistor connecting RT to GND sets the
switching frequency (f SW ). The relationship between
f SW and R RT is:
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. The satura-
tion current rating (I SAT ) must be high enough to ensure
that saturation can occur only above the maximum cur-
rent-limit value (I CL(MAX) ), given the tolerance of the on-
resistance of the low-side MOSFET and of the LIM
reference current (I LIM ). Combining these conditions,
f SW + ( 1x10 )x(f SW 2 )
R RT =
17.3 × 10 9
? 7
select an inductor with a saturation current (I SAT ) of:
I SAT ≥ 1.35 x I CL(TYP )
where I CL(TYP) is the typical current-limit set-point. The
where f SW is in Hz and R RT is in ? . For example, a
600kHz switching frequency is set with R RT = 27.2k ? .
Higher frequencies allow designs with lower inductor
values and less output capacitance. Peak currents and
I 2 R losses are lower at higher switching frequencies,
but core losses, gate-charge currents, and switching
losses increase.
Inductor Selection
Three key inductor parameters must be specified for
operation with the MAX15026: inductance value (L),
inductor saturation current (I SAT ), and DC resistance
(R DC ). To determine the inductance value, select the
ratio of inductor peak-to-peak AC current to DC average
current (LIR) first. For LIR values which are too high, the
RMS currents are high, and therefore I 2 R losses are
factor 1.35 includes R DS(ON) variation of 25% and 10%
for the LIM reference current error. A variety of inductors
from different manufacturers are available to meet this
requirement (for example, Coilcraft MSS1278-142ML
and other inductors from the same series).
Setting the Valley Current Limit
The minimum current-limit threshold must be high
enough to support the maximum expected load current
with the worst-case low-side MOSFET on-resistance
value as the R DS(ON) of the low-side MOSFET is used
as the current-sense element. The inductor’s valley cur-
rent occurs at I LOAD(MAX) minus one half of the ripple
current. The minimum value of the current-limit thresh-
old voltage (V ITH ) must be higher than the voltage on
the low-side MOSFET during the ripple-current valley:
V ITH DS ( ON , MAX ) × I LOAD ( MAX ) × ? 1 ?
> R
2 ?
high. Use high-valued inductors to achieve low LIR val-
ues. Typically, inductance is proportional to resistance
for a given package type, which again makes I 2 R losses
high for very low LIR values. A good compromise
?
?
LIR ?
?
between size and loss is a 30% peak-to-peak ripple cur-
rent to average-current ratio (LIR = 0.3). The switching
Maxim Integrated
where R DS(ON) is the on-resistance of the low-side
MOSFET in ohms. Use the maximum value for R DS(ON)
from the data sheet of the low-side MOSFET.
13
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX15026CETD+ | 功能描述:DC/DC 开关控制器 4.5-28V Synchronous Buck Controller 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 |
| MAX15026CETD+G1D | 制造商:Maxim Integrated Products 功能描述:LOW-COST, SMALL, 4.5V TO 28V WIDE OPERATING RANGE, DC-DC SYN - Rail/Tube |
| MAX15026CETD+T | 功能描述:DC/DC 开关控制器 4.5-28V Synchronous Buck Controller 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 |
| MAX15026CETD+TG1D | 制造商:Maxim Integrated Products 功能描述:LOW-COST, SMALL, 4.5V TO 28V WIDE OPERATING RANGE, DC-DC SYN - Tape and Reel |
| MAX15026CETD+TW | 制造商:Maxim Integrated Products 功能描述:LOW-COST SMALL 4.5V TO 28V WIDE OPERATING RANGE DC-DC CONT - Tape and Reel |
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