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參數(shù)資料
| 型號： | LM5071 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Power Over Ethernet PD Controller with Auxiliary Power Power Over Ethernet PD Controller with Auxiliary Power |
| 中文描述： | 通過以太網(wǎng)PD控制器與輔助電源以太網(wǎng)供電PD控制器電源與輔助電源 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 857K |
| 代理商： | LM5071 |
Classification
(Continued)
TABLE 2. Classification Levels and Required External
Resistors
Class
PMIN
PMAX
ICLASS
(MIN)
0mA
9mA
17mA
26mA
36mA
ICLASS
(MAX)
4mA
12mA
20mA
30mA
44mA
RCLASS
0
1
2
3
4
0.44W
0.44W
3.84W
6.49W
Reserved
12.95W
3.84W
6.49W
12.95W
Reserved
Open
150
82.5
54.9
38.3
Undervoltage Lockout (UVLO)
The IEEE 802.3af specification states that the PSE will
supply power to the PD within 400ms after completion of
detection. The LM5071 contains a programmable line Under
Voltage Lock Out (UVLO) circuit. The first resistor should be
connected between the V
to UVLO pins; the bottom resis-
tor in the divider should be connected between the UVLO
and UVLORTN pins.
The divider must be designed such that the voltage at the
UVLO pin equals 2.0V when V
reaches the desired mini-
mum operating level. If the UVLO threshold is not met, the
interface control and SMPS control will remain in standby.
UVLO hysteresis is accomplished with an internal 10uA
current source that is switched on and off into the impedance
of the UVLO set point divider. When the UVLO threshold is
exceeded, the current source is activated to instantly raise
the voltage at the UVLO pin. When the UVLO pin voltage
falls below the 2.00V threshold, the current source is turned
off, causing the voltage at the UVLO pin to fall. The LM5071
UVLO thresholds cannot be programmed lower than 25V,
the AUX pin should be used to force UVLO release below
25V.
There are many additional uses for the UVLO pin. The UVLO
function can also be used to implement a remote enable /
disable function. Pulling the UVLO pin down below the
UVLO threshold disables the interface and SMPS controller
unless forced on via AUX pin operation.
AUX Pin Operation
The AUX pin can be used to force operation (UVLO release)
of the interface and switching regulator at any input voltage
above 9.5V. This is especially useful for auxiliary input (wall
transformer) input voltages. The pin has a 2.5V threshold
(0.5V hysteresis) and an input impedance of approximately
350k
. The input resistor provides a defined pull down
impedance if the pin is left open by the user. An external pull
down resistor should be used to provide additional noise
immunity. The resultant pin voltage from the external resistor
divider should be well above the 2.5V threshold to ensure
proper auxiliary operation. See
Figure 4
for an example of a
simple yet robust auxiliary configuration.
20168422
FIGURE 4. Simplified Schematic Showing Auxiliary Implementation
L
www.national.com
11
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| LM5071EVAL | 功能描述:BOARD EVALUATION LM5071 RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:PowerWise® 產(chǎn)品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
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| LM5071MT-50 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Power Over Ethernet PD Controller with Auxiliary Power Power Over Ethernet PD Controller with Auxiliary Power |
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| LM5071MT-50-NOPB | 制造商:TI 制造商全稱:Texas Instruments 功能描述:LM5071 Power Over Ethernet PD Controller with Auxiliary Power Interface |
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