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| 型号： | MAX1777EEI+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 21/32页 |
| 文件大小： | 0K |
| 描述： | IC REG QD BUCK/LINEAR 28QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 拓扑： | 降压（降压）（2），线性（LDO）（2） |
| 功能： | 任何功能 |
| 输出数： | 4 |
| 频率 - 开关： | 200kHz ~ 500kHz |
| 电压/电流 - 输出 1： | 控制器 |
| 电压/电流 - 输出 2： | 控制器 |
| 电压/电流 - 输出 3： | 3.3V，100mA |
| 带 LED 驱动器： | 无 |
| 带监控器： | 无 |
| 带序列发生器： | 是 |
| 电源电压： | 4.5 V ~ 24 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 28-QSOP |
| 包装： | 带卷 (TR) |
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High-Efficiency, Quad Output, Main Power-
Supply Controllers for Notebook Computers
A negative current limit prevents excessive reverse
inductor currents when V OUT sinks current. The nega-
tive current-limit threshold is set to approximately 120%
of the positive current limit and therefore tracks the
positive current limit when ILIM_ is adjusted.
The current-limit threshold is adjusted with an external
voltage-divider at ILIM_. The current-limit threshold
adjustment range is from 50mV to 300mV. In the
adjustable mode, the current-limit threshold voltage is
precisely 1/10th the voltage at ILIM_. The threshold
defaults to 100mV when ILIM_ is connected to V CC .
The logic threshold for switchover to the 100mV default
value is approximately V CC - 1V.
Carefully observe the PC board layout guidelines to
ensure that noise and DC errors do not corrupt the cur-
rent-sense signals at CS_. Mount or place the device
close to the synchronous rectifier or sense resistor
(whichever is used) with short, direct traces, making a
Kelvin sense connection to the sense resistor. The cur-
rent-sense accuracy of Figure 8 is degraded if the
Schottky diode conducts during the synchronous recti-
fier on-time. To ensure that all current passes through
the sense resistor, connect the Schottky diode in paral-
lel with only the synchronous recifier (Figure 9) if the
voltage drop across the synchronous rectifier and
sense resistor exceeds the Schottky diode’s forward
voltage. Note that at high temperatures, the on-resis-
tance of the synchronous rectifier increases, and the
forward voltage of the Schottky diode decreases.
MAX1777
MAX1977
DH_
V+
MOSFET Gate Drivers (DH_, DL_)
The DH_ and DL_ gate drivers sink 2.0A and 3.3A
respectively of gate drive, ensuring robust gate drive for
high-current applications. The DH_ floating high-side
MOSFET drivers are powered by diode-capacitor charge
LX_
DL_
CS_
OUT_
pumps at BST_. The DL_ synchronous-rectifier drivers are
powered by LDO5.
The internal pulldown transistors that drive DL_ low
have a 0.6 ? typical on-resistance. These low on-resis-
tance pulldown transistors prevent DL_ from being
pulled up during the fast rise time of the inductor nodes
due to capacitive coupling from the drain to the gate of
the low-side synchronous-rectifier MOSFETs. However,
Figure 8. Current Sensing Using Sense Resistor
(MAX1777/MAX1977)
for high-current applications, some combinations of
high- and low-side MOSFETS may cause excessive
gate-drain coupling, which leads to poor efficiency and
EMI-producing shoot-through currents. Adding a resis-
tor in series with BST_ increases the turn-on time of the
MAX1777
MAX1977
DH_
V+
high-side MOSFETs at the expense of efficiency, without
degrading the turn-off time (Figure 10).
LX_
OUT_
BST
10 ?
5V
V IN
DL_
DH
CS_
LX
MAX1777
MAX1977
MAX1999
Figure 9. More Accurate Current Sensing with Adjusted
Schottky Connection
Figure 10. Reducing the Switching-Node Rise Time
______________________________________________________________________________________
21
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| MAX1778EUG | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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| MAX1778EUG+T | 功能描述:直流/直流开关转换器 Quad-Output TFT LCD w/Buffer RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1778EUG-T | 功能描述:直流/直流开关转换器 RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX1778EVKIT | 功能描述:电源管理IC开发工具 MAX1778/80/81/82 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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