参数资料
| 型号： | MAX8717ETI+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 19/30页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP 28-TQFN |
| 标准包装： | 60 |
| 应用： | 控制器，笔记本电脑电源系统 |
| 输入电压： | 4 V ~ 26 V |
| 输出数： | 2 |
| 输出电压： | 3.3V，5V，1 V ~ 5.5 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
| 包装： | 管件 |
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Interleaved High-Efficiency, Dual Power-Supply
Controllers for Notebook Computers
inductor ripple current. Therefore, the maximum load
TO ERROR
AMPLIFIER
capability is a function of the current-sense resistance,
inductor value, switching frequency, and duty cycle
FB
CSL
2V
ADJUSTABLE
OUTPUT
FIXED OUTPUT
FB = V CC
(V OUT / V IN ).
In forced-PWM mode, the MAX8716/MAX8717/
MAX8756/MAX8757 also implement a negative current
limit to prevent excessive reverse inductor currents
when V OUT is sinking current. The negative current-limit
threshold is set to approximately -120% of the positive
current limit and tracks the positive current limit when
ILIM is adjusted.
Connect ILIM_ to V CC for the 50mV default threshold, or
adjust the current-limit threshold with an external resis-
tor-divider at ILIM_. Use a 2μA to 20μA divider current
for accuracy and noise immunity. The current-limit
threshold adjustment range is from 50mV to 200mV. In
the adjustable mode, the current-limit threshold voltage
equals precisely 1/10 the voltage seen at ILIM_. The
logic threshold for switchover to the 50mV default value
is approximately V CC - 1V.
Figure 5. Dual Mode Feedback Decoder
Adjustable/Fixed Output Voltages
(Dual-Mode Feedback)
Connect FB1 and FB2 to V CC to enable the fixed SMPS
output voltages (3.3V and 5V, respectively, for the
MAX8716/MAX8717/MAX8757, and 1.5V and 1.8V for
the MAX8756, respectively), set by a preset, internal
resistive voltage-divider connected between CSL_ and
analog ground. See Figure 5. Connect a resistive volt-
age-divider at FB_ between CSL_ and GND to adjust
the respective output voltage between 1V and 5.5V.
Choose R2 (resistance from FB to AGND) to be approx-
imately 10k Ω and solve for R1 (resistance from OUT to
FB) using the equation:
Carefully observe the PCB layout guidelines to ensure
that noise and DC errors do not corrupt the differential
current-sense signals seen by CSH_ and CSL_. Place
the IC close to the sense resistor with short, direct
traces, making a Kelvin-sense connection to the cur-
rent-sense resistor.
MOSFET Gate Drivers (DH_, DL_)
The DH_ and DL_ drivers are optimized for driving
moderate-sized high-side, and larger low-side power
MOSFETs. This is consistent with the low duty factor
seen in notebook applications, where a large V IN -
V OUT differential exists. The high-side gate drivers
(DH_) source and sink 2A, and the low-side gate dri-
vers (DL_) source 1.7A and sink 3.3A. This ensures
robust gate drive for high-current applications. The
R 1 = R 2 ?
? 1 ?
? V OUT _
? V FB _
?
?
DH_ floating high-side MOSFET drivers are powered by
diode-capacitor charge pumps at BST_ (Figure 6) while
the DL_ synchronous-rectifier drivers are powered
directly by the external 5V supply (V DD ).
where V FB_ = 1V nominal.
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). At the next
rising edge of the internal oscillator, the PWM controller
does not initiate a new cycle unless the current-sense
signal drops below the current-limit threshold. The
actual maximum load current is less than the peak cur-
rent-limit threshold by an amount equal to half of the
Adaptive dead-time circuits monitor the DL_ and DH_ dri-
vers and prevent either FET from turning on until the other
is fully off. The adaptive driver dead-time allows operation
without shoot-through with a wide range of MOSFETs,
minimizing delays and maintaining efficiency. There must
be a low-resistance, low-inductance path from the DL_
and DH_ drivers to the MOSFET gates for the adaptive
dead-time circuits to work properly; otherwise, the sense
circuitry in the MAX8716/MAX8717/MAX8756/MAX8757
interprets the MOSFET gates as “off” while charge actually
remains. Use very short, wide traces (50 mils to 100 mils
wide if the MOSFET is 1in from the driver).
______________________________________________________________________________________
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8717ETI+ | 功能描述:软开关 PWM 控制器 Dual Power-Supply Controller RoHS:否 制造商:Fairchild Semiconductor 输出端数量: 输出电流: 开关频率: 工作电源电压:30 V 电源电流: 最大工作温度:+ 105 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel |
| MAX8717ETI+T | 功能描述:电流和电力监控器、调节器 Dual 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 |
| MAX8717ETI-T | 功能描述:电流和电力监控器、调节器 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 |
| MAX8717EVKIT | 制造商:Maxim Integrated Products 功能描述:HIGH-EFFICIENCY DUAL POWER-SUPPLY - Rail/Tube |
| MAX8718ETA | 制造商:Maxim Integrated Products 功能描述:HIGH-VOLTAGE LOW-POWER LINEAR REGU - Rail/Tube |
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