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| 型号： | MAX8548EUB+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/18页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 10-UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 120kHz |
| 占空比： | 95% |
| 电源电压： | 2.7 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 ~ 85°C |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
Low-Cost, Wide Input Range, Step-Down
Controllers with Foldback Current Limit
with DH and DL to slow down the switching transitions.
However, adding series resistors increases the power
dissipation of the MOSFET, so ensure temperature rat-
ings of the MOSFET are not exceeded.
Input-Capacitor Selection
The input capacitors (C2 and C3 in Figure 1) reduce
noise injection and current peaks drawn from the input
supply. The input capacitor must meet the ripple-cur-
rent requirement (I RMS ) imposed by the switching cur-
rents. The RMS input ripple current is given by:
zero close to the LC double pole when possible to
negate the sharp phase shift of the typically high-Q
double LC pole (see the Compensation Design sec-
tion). Aluminum electrolytic or POS capacitors are rec-
ommended. Higher output current requires multiple
capacitors to meet the output ripple voltage.
The MAX8545/MAX8546/MAX8548s’ response to a load
transient depends on the selected output capacitor. After
a load transient, the output instantly changes by (ESR x
Δ I LOAD ) + (ESL x dI/dt). Before the controller can
respond, the output deviates further depending on the
I RMS = I LOAD ×
V OUT × ( V IN ? V OUT )
V IN
inductor and output capacitor values. After a short period
of time (see the Typical Operating Characteristics ), the
controller responds by regulating the output voltage back
to its nominal state. The controller response time
V RIPPLE ( C ) =
V RIPPLE ( ESL ) = IN
I P ? P = ?
? ? V
f SW × L
?
? ?
IN ?
V GS ( MIN ) = V L ?
For optimal circuit reliability, choose a capacitor that
has less than 10°C temperature rise at the RMS current.
I RMS is maximum when the input voltage equals 2 x
V OUT , where I RMS = 1/2 I LOAD .
Output Capacitor Selection
The key parameters for the output capacitor are the
actual capacitance value, the equivalent series resis-
tance (ESR), the equivalent series inductance (ESL),
and the voltage-rating requirements. All these parame-
ters affect the overall stability, output ripple voltage,
and transient response.
The output ripple has three components: variations in the
charge stored in the output capacitor, the voltage drop
across the ESR, and the voltage drop across the ESL.
V RIPPLE = V RIPPLE(ESR) + V RIPPLE(C) + V RIPPLE(ESL)
The output voltage ripple as a consequence of the ESR
and output capacitance is:
V RIPPLE ( ESR ) = I P ? P × ESR
I P ? P
8 × C OUT × f SW
V × ESL
L + ESL
? V IN ? V OUT ? ? V OUT ?
?
where I P-P is the peak-to-peak inductor current (see the
Inductor Selection section).
While these equations are suitable for initial capacitor
selection to meet the ripple requirement, final values
may also depend on the relationship between the LC
double-pole frequency and the capacitor ESR-zero fre-
quency. Generally, the ESR zero is higher than the LC
double pole; however, it is preferable to keep the ESR
depends on the closed-loop bandwidth. Higher band-
width results in faster response time, preventing the out-
put voltage from further deviation. Do not exceed the
capacitor’s voltage or ripple-current ratings .
Boost Diode and Capacitor Selection
A low-current Schottky diode, such as the CMPSH-3
from Central Semiconductor, works well for most appli-
cations. Do not use large power diodes since higher
junction capacitance can charge up BST to LX voltage
that could exceed the device rating of 6V. The boost
capacitor should be in the range of 0.1μF to 0.47μF,
depending on the specific input and output voltages
and the external components and PCB layout. The
boost capacitance needs to be as large as possible to
prevent it from charging to excessive voltage, but small
enough to adequately charge during the minimum low-
side MOSFET conduction time, which happens at the
maximum operating duty cycle (this occurs at the mini-
mum input voltage). In addition, ensure the boost
capacitor does not discharge to below the minimum
gate-to-source voltage required to keep the high-side
MOSFET fully enhanced for lowest on-resistance. This
minimum gate-to-source voltage V GS(MIN) is deter-
mined by:
Q G
C BOOST
where Q G is the total gate charge of the high-side
MOSFET and C BOOST is the boost capacitor value.
Compensation Design
The MAX8545/MAX8546/MAX8548 use a voltage-mode
control scheme that regulates the output voltage. This is
done by comparing the error amplifier’s output (COMP) to
a fixed internal ramp. The inductor and output capacitor
create a double pole at the resonant frequency, which
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| MAX8550AETI+ | 功能描述:电压模式 PWM 控制器 Integrated DDR Power Supply Solution 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 |
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