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| 型号： | MAX8744AETJ+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/36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
V GS ( TH ) > V IN ? RSS ?
In forced-PWM mode, the MAX8744A/MAX8745A 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 approxi-
mately 120% of the positive current limit and tracks the
positive current limit when ILIM is adjusted.
Connect ILIM to LDO5 for the 50mV default threshold,
or adjust the current-limit threshold with an external
resistor-divider at ILIM. Use a 2μA to 20μA divider cur-
rent 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 default value is
approximately V LDO5 - 1V.
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
DH_ floating high-side MOSFET drivers are powered by
Applications with high input voltages and long inductive
driver traces may require additional gate-to-source
capacitance to ensure fast-rising LX_ edges do not pull
up the low-side MOSFETs gate, causing shoot-through
currents. The capacitive coupling between LX_ and DL_
created by the MOSFET’s gate-to-drain capacitance
(C GD = C RSS ), gate-to-source capacitance (C GS = C ISS
- C GD ), and additional board parasitics should not
exceed the following minimum threshold:
? C ?
? C ISS ?
Lot-to-lot variation of the threshold voltage may cause
problems in marginal designs.
Power-Good Output (PGOOD_)
PGOOD_ is the open-drain output of a comparator that
continuously monitors both SMPS output voltages and
the auxiliary LDO output for undervoltage conditions.
PGOOD_ is actively held low in shutdown ( SHDN =
GND), standby (ON3 = ON5 = ONA = GND), soft-start,
and soft-shutdown. Once the soft-start sequence termi-
nates, PGOOD_ becomes high impedance as long as
the outputs are above 90% of the nominal regulation volt-
age set by FB_. PGOOD_ goes low once the respective
output drops 10% below its nominal regulation point, an
SMPS output overvoltage fault occurs, or ON_ or SHDN
is low. For a logic-level PGOOD_ output voltage, connect
an external pullup resistor between PGOOD_ and LDO5.
A 100k Ω pullup resistor works well in most applications.
charge pumps at BST_ while the DL_ synchronous-rec-
tifier drivers are powered directly by the fixed 5V linear
regulator (LDO5).
POWER-GOOD
FAULT
PROTECTION
Adaptive dead-time circuits monitor the DL_ and DH_
drivers and prevent either FET from turning on until the
0.9 x INT REF_
0.7 x INT REF_
1.11 x INT REF_
INTERNAL FB
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; other-
wise, the sense circuitry in the MAX8744A/MAX8745A
ENABLE OVP
ENABLE UVP
interprets the MOSFET gates as “off” while charge actu-
ally remains. Use very short, wide traces (50 mils to 100
6144
CLK
FAULT
LATCH
FAULT
mils wide if the MOSFET is 1in from the driver).
The internal pulldown transistor that drives DL_ low is
robust, with a 0.6 Ω (typ) on-resistance. This helps prevent
DL_ from being pulled up due to capacitive coupling from
the drain to the gate of the low-side MOSFETs when the
inductor node (LX_) quickly switches from ground to V IN .
POR
Figure 6. Power-Good and Fault Protection
POWER-GOOD
______________________________________________________________________________________
23
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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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