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| 型号： | MAX8745ETJ+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 24/36页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR PWR SUP QUAD 32TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 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： | 管件 |
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High-Efficiency, Quad-Output, Main Power-
Supply Controllers for Notebook Computers
Table 5. Operating Modes Truth Table
MODE
Power-Up
Run
Output Overvoltage
(OVP) Protection
(MAX8744)
Output Undervoltage
Protection (UVP)
Standby
Shutdown
Thermal Shutdown
Switchover Fault
CONDITION
LDO5 < UVLO threshold
SHDN = high, ON3 or ON5 enabled
Either output > 111% of nominal level
Either output < 70% of nominal level,
UVP is enabled 6144 clock cycles
(1/f OSC ) after the output is enabled
ON5 and ON3 < startup threshold,
SHDN = high
SHDN = low
T J > +160°C
Excessive current on LDO5 switchover
transistors
COMMENT
Transitions to discharge mode after V IN POR and after REF
becomes valid. LDO5, REF remain active. DL_ is active
(high).
Normal operation.
Exited by POR or cycling SHDN , ON3, or ON5.
Exited by POR or cycling SHDN , ON3, or ON5.
DL_ stays high. LDO5 active.
All circuitry off.
Exited by POR or cycling SHDN , ON3, or ON5.
DL3 and DL5 go high before LDO5 turns off. They remain
high as long as possible thereafter.
Exited by POR or cycling SHDN , ON3, or ON5.
V GS ( TH ) > V IN ? RSS ?
inductor node (LX_) quickly switches from ground to V IN .
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.
Fault Protection
Output Overvoltage Protection (OVP)—
MAX8744 Only
If the output voltage of either SMPS rises above 111% of
its nominal regulation voltage and the OVP protection is
enabled, the controller sets the fault latch, pulls PGOOD
low, shuts down the SMPS controllers that tripped the
fault, and immediately pulls DH_ low and forces DL_
high. This turns on the synchronous-rectifier MOSFETs
with 100% duty, rapidly discharging the output capaci-
tors and clamping both outputs to ground. However,
immediately latching DL_ high typically causes slightly
negative output voltages due to the energy stored in the
output LC at the instant the OVP occurs. If the load can-
not tolerate a negative voltage, place a power Schottky
diode across the output to act as a reverse-polarity
clamp. If the condition that caused the overvoltage per-
sists (such as a shorted high-side MOSFET), the battery
blows. The other output is shut down using the soft-shut-
down sequence. Cycle LDO5 below 1V or toggle either
24
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8745ETJ+ | 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 |
| MAX8745ETJ+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 |
| MAX874C/D | 功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
| MAX874CPA | 功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
| MAX874CPA+ | 功能描述:基准电压& 基准电流 RoHS:否 制造商:STMicroelectronics 产品:Voltage References 拓扑结构:Shunt References 参考类型:Programmable 输出电压:1.24 V to 18 V 初始准确度:0.25 % 平均温度系数（典型值）:100 PPM / C 串联 VREF - 输入电压（最大值）: 串联 VREF - 输入电压（最小值）: 分流电流（最大值）:60 mA 最大工作温度:+ 125 C 封装 / 箱体:SOT-23-3L 封装:Reel |
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