參數(shù)資料
型號(hào)： MAX5986AETE+
廠商： Maxim Integrated
文件頁(yè)數(shù)： 13/23頁(yè)
文件大?。?/td> 843K
描述： IC POE SWITCH PSE 16TQFN
標(biāo)準(zhǔn)包裝： 60
類型： 以太網(wǎng)供電控制器 PD 開(kāi)關(guān)（PoE）
應(yīng)用： 供電設(shè)備（PSE）
內(nèi)部開(kāi)關(guān)： 是
電流限制： 201mA
電源電壓： 8.7 V ~ 60 V
工作溫度： -40°C ~ 85°C
安裝類型： 表面貼裝
封裝/外殼： 16-WQFN 裸露焊盤(pán)
供應(yīng)商設(shè)備封裝： 16-TQFN-EP（5x5）
包裝： 管件
MAX5986AMAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
  13
Maxim Integrated
Detailed Description
PD Interface
The devices include complete interface functions for a
PD to comply with the IEEE 802.3af standard as a Class
1/Class 2 PD. The devices provide the detection and
classification signatures using a single external signa-
ture resistor. An integrated MOSFET provides isolation
from the buck converter when the PSE has not applied
power. The devices guarantee a leakage current offset of
less than 10礎(chǔ) during the detection phase. The devices
feature power-mode undervoltage-lockout (UVLO) with
wide hysteresis and long deglitch time to compensate for
twisted-pair-cable resistive drop and to ensure glitch-free
transitions between detection, classification, and power-
on/-off modes.
Operating Modes
The devices operate in three different modes depending
on V
DD
. The three modes are detection mode, classifica-
tion mode, and power mode. The device is in detection
mode when V
DD
 is between 1.4V and 10.1V, classifica-
tion mode when V
DD
 is between 12.6V and 20V, and
power mode when the input voltage exceeds V
ON
.
Detection Mode (1.4V < V
DD
 < 10.1V)
In detection mode, the devices provide a signature
differential resistance to V
DD
. During detection, the
power-sourcing equipment (PSE) applies two voltages to
V
DD
, both between 1.4V and 10.1V with a minimum 1V
increment. The PSE computes the differential resistance
to ensure the presence of the 24.9k?signature resis-
tor. Connect the 24.9k?signature resistor (R
SIG
) from
RREF to GND for proper signature detection. The device
applies V
DD
 to RREF when in detection mode, and the
V
DD
 offset current due to the device is less than 10礎(chǔ).
The DC offset due to protection diodes does not signifi-
cantly affect the signature resistance measurement.
Classification Mode (12.6V < V
DD
 < 20V)
In classification mode, the devices sink Class 1/Class 2
classification currents. The PSE applies a classification
voltage between 12.6V and 20V, and measures the clas-
sification currents. The devices use the external 24.9k?
resistor (R
SIG
) and the CLASS2 pin to set the classifica-
tion current at 10.5mA (Class 1) or 18.5mA (Class 2). The
MAX5986A only provides the Class 1 operation, while the
MAX5986B/MAX5987A provide either Class 1 (CLASS2 =
GND) or Class 2 (CLASS2 = VDRV). The PSE uses this to
determine the maximum power to deliver. The classifica-
tion current includes current drawn by the supply current
of the device so the total current drawn by the PD is with-
in the IEEE 802.3af standard. The classification current
is turned off when the device leaves classification mode.
Power Mode (V
DD
 > V
ON
)
In power mode, the devices have the isolation MOSFET
between V
DD
  and V
CC
  fully on. The MAX5987A has
the buck regulator enabled and the LDO enabled. The
MAX5986AMAX5986C can be in either wake mode,
sleep mode, or ultra-low power mode. The buck regulator
is enabled when the MAX5986AMAX5986C is in wake
mode.
The devices enter power mode when V
DD
 rises above
the undervoltage lockout threshold (V
ON
). When V
DD
 
rises above V
ON
, the device turns on the internal p-chan-
nel isolation MOSFET to connect V
CC
 to V
DD
 with inrush
current limit internally set to 49mA (typ). The isolation
MOSFET is fully turned on when V
CC
 is near V
DD
 and the
inrush current is below the inrush limit. Once the isolation
MOSFET is fully turned on, the device changes the cur-
rent limit to 201mA (MAX5986A) or 323mA (MAX5986B/
MAX5986C/MAX5987A). The buck converter turns on
90ms (MAX5986A) or 123ms (MAX5986B/MAX5986C/
MAX5987A) after the isolation MOSFET turns on fully.
Undervoltage Lockout
The devices operate with up to a 60V supply voltage with
a turn-on UVLO threshold (V
ON
) at 35.4V/38.7V (typ),
and a turn-off UVLO threshold (V
OFF
) at 31.4V (typ).
When the input voltage is above V
ON
, the device enters
power mode and the internal isolation MOSFET is turned
on. When the input voltage is below V
OFF
 for more than
t
OFF_DLY
, the MOSFET and the buck converter are off.
LED Driver (MAX5986AMAX5986C)
The MAX5986AMAX5986C drive an LED, or multiple
LEDs in series, with a maximum LED voltage of 6.5V.
In sleep mode and ultra-low power mode, the LED cur-
rent is pulse width modulated with a duty cycle of 25%
and the amplitude is set by R 
SL
. The LED driver current
amplitude is programmable from 10mA to 20mA using R 
SL
 according to the formula:
I
LED
 = 646/R 
SL
 (mA)
where R 
SL
 is in k?
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX5986AETE+ 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 IEEE802.3 af PD w/ DC/DC Conv RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX5986AETE+T 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 IEEE802.3 af PD w/ DC/DC Conv RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX5986BETE+ 功能描述:以太網(wǎng) IC IEEE802.3 AF HI EFFICIENCY PD RoHS:否 制造商:Micrel 產(chǎn)品:Ethernet Switches 收發(fā)器數(shù)量:2 數(shù)據(jù)速率:10 Mb/s, 100 Mb/s 電源電壓-最大:1.25 V, 3.45 V 電源電壓-最小:1.15 V, 3.15 V 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-64 封裝:Tray
MAX5986BETE+T 功能描述:PMIC 解決方案 IEEE802.3 AF HI EFFICIENCY PD RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
MAX5986EVKIT# 功能描述:電源管理IC開(kāi)發(fā)工具 MAX5986 Eval Kit RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
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