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参数资料
| 型号： | MAX5945CAX+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/44页 |
| 文件大小： | 0K |
| 描述： | IC NETWORK PWR CTRL 36-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1,000 |
| 控制器类型： | 网络电源控制器 |
| 接口： | I²C |
| 电源电压： | 3.3V |
| 电流 - 电源： | 4.2mA |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 36-BSOP（0.295"，7.50mm 宽） |
| 供应商设备封装： | 36-SSOP |
| 包装： | 带卷 (TR) |
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MOSFET Gate Driver
Connect the gate of the external n-channel MOSFET to
GATE_. An internal 50A current source pulls GATE_ to
(VEE + 10V) to turn on the MOSFET. An internal 40A
current source pulls down GATE_ to VEE to turn off the
MOSFET.
The pullup and pulldown current controls the maximum
slew rate at the output during turn-on or turn-off. The
pullup current (gate-charging current) is programmable
using R23h[5-7]. Use the following equation to set the
maximum slew rate:
where CGD is the total capacitance between GATE and
DRAIN of the external FET. Current limit and the capac-
itive load at the drain control the slew rate during start-
up. During current-limit regulation, the MAX5945
manipulates the GATE_ voltage to control the voltage at
SENSE_. A fast pulldown activates if SENSE_ over-
shoots the limit threshold. The fast pulldown current
increases with the amount of overshoot. The maximum
fast pulldown current is 100mA.
During turn-off, when the GATE voltage reaches a value
lower than 1.2V, a strong pulldown switch is activated
to keep the FET securely off.
Digital Logic
VDD supplies power for the internal logic circuitry. VDD
ranges from +1.71V to +3.7V and determines the logic
thresholds for the CMOS connections (SDAIN,
SDAOUT, SCL, AUTO, SHD_, A_). This voltage range
enables the MAX5945 to interface with a nonisolated
low-voltage microcontroller. The MAX5945 checks the
digital supply for compatibility with the internal logic.
The MAX5945 also features a VDD undervoltage lockout
(VDDUVLO) of +1.35V. A VDDUVLO condition keeps the
MAX5945 in reset and the ports shut off. Bit 0 in the
supply event register shows the status of VDDUVLO
(Table 11) after VDD has recovered. All logic inputs and
outputs reference to DGND. DGND and AGND are
completely isolated internally to the MAX5945. In a
completely isolated system, the digital signal can be
referenced indifferently to VAGND or VEE or at voltages
even higher than AGND (up to 60V). VDD - VDGND must
be greater than 3.0V when VDGND ≤ (VEE + 3.0V)
When using the AC disconnect detection feature,
AGND must be connected directly to DGND and VDD
must be greater than +3V. In this configuration, con-
nect DGND to AGND at a single point in the system as
close to MAX5945 as possible.
Hardware Shutdown
SHD_ shuts down the respective ports without using
the serial interface. Hardware shutdown offers an emer-
gency turn-off feature that allows a fast disconnect of
the power supply from the port. Pull SHD_ low to
remove power.
Interrupt
The MAX5945 contains an open-drain logic output (INT)
that goes low when an interrupt condition exists. R00h
and R01h (Tables 5 and 6) contain the definitions of the
interrupt registers. The mask register R01h determines
events that trigger an interrupt. As a response to an
interrupt, the controller reads the status of the event reg-
ister to determine the cause of the interrupt and takes
subsequent actions. Each interrupt event register also
contains a clear-on-read (CoR) register. Reading
through the CoR register address clears the interrupt.
INT remains low when reading the interrupt through the
read-only addresses. For example, to clear a startup
fault on port 4 read address 09h (see Table 10). Use the
global pushbutton bit on register 1Ah (bit 7, Table 22) to
clear interrupts, or use a software or hardware reset.
Undervoltage and Overvoltage Protection
The MAX5945 contains several undervoltage and over-
voltage protection features. Table 11 in the Register Map
and Description section shows a detailed list of the
undervoltage and overvoltage protection features. An
internal VEE undervoltage lockout (VEEUVLO) circuit
keeps the MOSFET off and the MAX5945 in reset until
VAGND - VEE exceeds 29V for more than 3ms. An internal
VEE overvoltage (VEE_OV) circuit shuts down the ports
when (VAGND - VEE) exceeds 60V. The digital supply also
contains an undervoltage lockout (VDDUVLO).
V
t
I
C
OUT
GATE
GD
=
MAX5945
Quad Network Power Controller
for Power-Over-LAN
______________________________________________________________________________________
17
Figure 4. Foldback Current Characteristics
50V
30V
VSU_LIM
VSU_LIM / 3
(VSENSE_ - VEE)
(VOUT_ - VEE)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5945EAX | 功能描述:热插拔功率分布 RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5945EAX+ | 功能描述:热插拔功率分布 IEEE 802.3af Quad Net Pwr Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5945EAX+T | 功能描述:热插拔功率分布 IEEE 802.3af Quad Net Pwr Controller RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5945EAX-T | 功能描述:热插拔功率分布 RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| MAX5945EVKIT | 功能描述:电源管理IC开发工具 Evaluation Kit/Evaluation System for the MAX5945 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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