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参数资料
| 型号： | MAX8744AETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/36页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP QUAD 32TQFN |
| 标准包装： | 2,500 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 6 V ~ 26 V |
| 输出数： | 4 |
| 输出电压： | 3.3V，5V，1 V ~ 26 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 32-WFQFN 裸露焊盘 |
| 供应商设备封装： | 32-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
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High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
The switching waveforms may appear noisy and asyn-
chronous when light loading causes pulse-skipping
operation, but this is a normal operating condition that
results in high light-load efficiency. Trade-offs in PFM
noise vs. light-load efficiency are made by varying the
FB
TO ERROR
AMPLIFIER
ADJUSTABLE
OUTPUT
inductor value. Generally, low inductor values produce
a broader efficiency vs. load curve, while higher values
result in higher full-load efficiency (assuming that the
coil resistance remains fixed) and less output-voltage
ripple. Penalties for using higher inductor values
include larger physical size and degraded load-tran-
sient response (especially at low input-voltage levels).
Output Voltage
LDO5
9R
R
DC output accuracy specifications in the Electrical
Characteristics table refer to the error comparator’s
threshold. When the inductor continuously conducts,
the MAX8744A/MAX8745A regulate the peak of the out-
put ripple, so the actual DC output voltage is lower than
the slope-compensated trip level by 50% of the output
ripple voltage. For PWM operation (continuous conduc-
OUT
FIXED OUTPUT
FB = LDO5
? ? ? ?
V OUT ( PWM ) = V NOM ? 1 ?
?
?
?
?
R FBHI = R FBLO ?
? 1 ?
tion), the output voltage is accurately defined by the fol-
lowing equation:
? A SLOPE V RIPPLE ? ? V RIPPLE ?
V IN 2
where V NOM is the nominal output voltage, A SLOPE
equals 1.1%, and V RIPPLE is the output ripple voltage
(V RIPPLE = ESR x Δ I INDUCTOR , as described in the
Output Capacitor Selection section).
In discontinuous conduction (I OUT < I LOAD(SKIP) ), the
MAX8744A/MAX8745A regulate the valley of the output
ripple, so the output voltage has a DC regulation level
higher than the error-comparator threshold. For PFM
operation (discontinuous conduction), the output volt-
age is approximately defined by the following equation:
Figure 5. Dual Mode Feedback Decoder
and solve for R FBHI (resistance from the output to FB)
using the equation:
? V OUT _ ?
? V FB _ ?
where V FB_ = 2V nominal.
When adjusting both output voltages, set the 3.3V
SMPS lower than the 5V SMPS. LDO5 connects to the
5V output (CSL5) through an internal switch only when
CSL5 is above the LDO5 bootstrap threshold (4.5V)
and the soft-start sequence for the CSL5 side has com-
pleted. Bootstrapping works most effectively when the
fixed output voltages are used. Once LDO5 is boot-
V OUT ( PFM ) = V NOM +
1 ? f SW ?
2 ? ? f OSC ? ?
I IDLE ESR
strapped from CSL5, the internal 5V linear regulator
turns off. This reduces the internal power dissipation
and improves efficiency at higher input voltages.
where V NOM is the nominal output voltage, f OSC is the
maximum switching frequency set by the internal oscil-
lator, f SW is the actual switching frequency, and I IDLE is
the idle mode inductor current when pulse skipping.
Connect FB3 and FB5 to LDO5 to enable the fixed
SMPS output voltages (3.3V and 5V, respectively), set
by a preset, internal resistive voltage-divider connected
between the output (CSL_) and analog ground.
Connect a resistive voltage-divider at FB_ between the
output (CSL_) and GND to adjust the respective output
voltage between 2V and 5.5V (Figure 5). Choose R FBLO
(resistance from FB to GND) to be approximately 10k Ω
Current-Limit Protection (ILIM)
The current-limit circuit uses differential current-sense
inputs (CSH_ and CSL_) to limit the peak inductor cur-
rent. If the magnitude of the current-sense signal
exceeds the current-limit threshold, the PWM controller
turns off the high-side MOSFET (Figure 3). The actual
maximum load current is less than the peak current-
limit threshold by an amount equal to half of the induc-
tor ripple current. Therefore, the maximum load
capability is a function of the current-sense resistance,
inductor value, switching frequency, and duty cycle
(V OUT /V IN ).
22
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8744AEVKIT+ | 制造商:Maxim Integrated Products 功能描述:MAX8744A EVAL KIT - Rail/Tube |
| MAX8744ETJ+ | 功能描述:电流型 PWM 控制器 Quad-Out Main Power Supply Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX8744ETJ+T | 功能描述:电流和电力监控器、调节器 Quad-Out Main Power Supply Controller RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX8744EVKIT | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
| MAX8744EVKIT+ | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY QUAD OUTPUT MAIN - Rail/Tube |
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