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| 型号： | MAX8505EEE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/15页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3A 16QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.8 V ~ 4.68 V |
| 输入电压： | 2.6 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 500kHz，1MHz |
| 电流 - 输出： | 3A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 16-QSOP |
3A, 1MHz, 1% Accurate, Internal Switch
Step-Down Regulator with Power-OK
Output Voltage Selection
R 2 = R 3 × ? OUT ? 1 ?
V RIPPLE ( C ) =
I P ? P
V RIPPLE ( ESL ) = × ESL or P ? P × ESL ,
The output voltage of the MAX8505 can be adjusted
from 0.8V to 85% of the input voltage at 500kHz or up
to 80% of the input voltage at 1MHz. This is done by
connecting a resistive-divider (R2 and R3) between the
output and the FB pin (see the Typical Operating
Circuit ). For best results, keep R3 below 50k ? and
select R2 using the following equation:
? V ?
? V REF ?
where V REF = 0.8V.
Inductor Design
When choosing the inductor, the key parameters are
inductor value (L) and peak current (I PEAK ). The
following equation includes a constant, denoted as LIR,
which is the ratio of peak-to-peak inductor AC current
(ripple current) to maximum DC load current. A higher
value of LIR allows smaller inductance but results in
V RIPPLE = V RIPPLE ( C ) 2 + V RIPPLE ( ESR ) 2 + V RIPPLE ( ESL ) 2
where the output ripples due to output capacitance,
ESR, and ESL are:
I P ? P
8 × C OUT × f S
V RIPPLE ( ESR ) = I P ? P × ESR
I
t ON t OFF
or, whichever is greater.
The ESR is the main contribution to the output voltage
ripple.
I P-P , the peak-to-peak inductor current, is:
× OUT
higher losses and ripple. A good compromise between
size and losses is found at approximately 20% to 30%
ripple-current to load-current ratio (LIR = 0.20 to 0.30):
I P ? P =
( V IN ? V OUT )
f S × L
V
V IN
L = OUT
V × (1 ? D)
I OUT × LIR × f S
where f S is the switching frequency and
Use these equations for initial capacitor selection,
but determine final values by testing a prototype or
evaluation circuit. As a rule, a smaller ripple current
results in less output voltage ripple. Since the inductor
LIR = 2 × PEAK OUT
( I ? I
I OUT
)
ripple current is a factor of the inductor value, the
output voltage ripple decreases with larger inductance.
Use ceramic capacitors for their low ESR and ESL at the
switching frequency of the converter. The low ESL of
Choose an inductor with a saturation current at least as
high as the peak inductor current. Additionally, verify
the peak inductor current does not exceed the current
limit. The inductor selected should exhibit low losses at
the chosen operating frequency.
Output Capacitor Design and Output Ripple
The key selection parameters for the output capacitor
are capacitance, ESR, ESL, and the voltage rating
requirements. These affect the overall stability, output
ripple voltage, and transient response of the DC-DC
converter. The output ripple occurs due to variations in
the charge stored in the output capacitor, the voltage
drop due to the capacitor’s ESR, and the voltage drop
due to the capacitor’s ESL. Calculate the output voltage
ripple due to the output capacitance, ESR, and ESL as:
ceramic capacitors makes ripple voltages negligible.
Load-transient response depends on the selected
output capacitor. During a load transient, the output
instantly changes by ESR I LOAD . Before the controller
can respond, the output deviates further, depending on
the inductor and output capacitor values. After a short
time (see Transient Response in the Typical Operating
Characteristics), the controller responds by regulating the
output voltage back to its nominal state. The controller
response time depends on the closed-loop bandwidth,
the inductor value, and the slew rate of the transconduc-
tance amplifier. A higher bandwidth yields a faster
response time, thus preventing the output from deviating
further from its regulating value.
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相关代理商/技术参数 |
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|---|---|
| MAX8505EVKIT | 制造商:Maxim Integrated Products 功能描述:3A, 1MHZ, 1% ACCURATE, INTERNAL SWITCH STEP-D - Bulk |
| MAX8506ETE | 功能描述:直流/直流开关转换器 PWM Step-Down DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8506ETE+ | 功能描述:直流/直流开关转换器 DC/DC Converter DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8506ETE+T | 功能描述:直流/直流开关转换器 DC/DC Converter DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8506ETE-T | 功能描述:直流/直流开关转换器 DC/DC Converter DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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