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參數資料
| 型號： | MAX5971AETI+ |
| 廠商： | Maxim Integrated |
| 文件頁數： | 17/22頁 |
| 文件大小： | 2126K |
| 描述： | IC CTRLR PD IEEE 802.3AF 28WQFN |
| 產品培訓模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標準包裝： | 60 |
| 類型： | 以太網供電控制器 PD 開關（PoE） |
| 應用： | 供電設備（PSE） |
| 內部開關： | 是 |
| 電流限制： | 可調 |
| 電源電壓： | 32 V ~ 60 V |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 28-WFQFN 裸露焊盤 |
| 供應商設備封裝： | 28-TQFN-EP（5x5） |
| 包裝： | 管件 |
______________________________________________________________________________________ 17
Single-Port, 40W, IEEE 802.3af/802.3at PSE
Controller with Integrated MOSFET
Overcurrent Protection
The MAX5971A has an internal sense resistor, R
SENSE
(see the Simplified Diagram), connected between the
source of the internal MOSFET and V
EE
to monitor the
load current. Under normal operating conditions, the
current through R
SENSE
(I
RSENSE
) never exceeds the
threshold I
LIM
. If I
RSENSE
exceeds I
LIM
, an internal
current-limiting circuit regulates the gate voltage of the
internal MOSFET, limiting the current. During transient
conditions, if I
RSENSE
exceeds I
LIM
by more than 2A, a
fast pulldown circuit activates to quickly recover from the
current overshoot.
In the normal powered state, the MAX5971A checks for
overcurrent conditions, as determined by I
CUT
= ~88%
of I
LIM
. The t
FAULT
counter sets the maximum allowed
continuous overcurrent period. This timer is incremented
both in startup and in normal powered state, but under
different conditions. During startup, the counter increas-
es when I
RSENSE
exceeds I
LIM
, while in the normal pow-
ered state the counter increases when I
RSENSE
exceeds
I
CUT
. It decreases at a slower pace when I
RSENSE
drops below I
LIM
or I
CUT
. A slower decrement for the
t
FAULT
counter allows for detection of repeated short-
duration overcurrent events. When the counter reaches
the t
FAULT
limit, the MAX5971A powers down the port.
For a continuous overstress, a fault occurs exactly after
a period of t
FAULT
.
After a power-off due to an overcurrent fault, the t
FAULT
timer is not immediately reset but starts decrementing.
The MAX5971A allows the port to be powered on only
when the t
FAULT
counter reaches zero. This feature sets
an automatic port power duty-cycle protection to the
internal MOSFET to avoid overheating.
In the normal powered state, the I
LIM
and I
CUT
thresh-
olds are set automatically according to the classification
result (see Table 2 for classification results based on
detection current, and the Electrical Characteristics table
for the corresponding thresholds). During startup, I
LIM
is
always set to 420mA regardless of the detected class.
Foldback Current
During startup and normal operation, an internal circuit
senses the port voltage and reduces the current-limit
value and the overcurrent threshold when (V
AGND
-
V
OUT
) < 27V. The foldback function helps to reduce the
power dissipation on the internal MOSFET. The current
limit eventually reduces down to I
TH_FB
when (V
AGND
-
V
OUT
) < 10V (see Figure 3).
Figure 3. Foldback Current Characteristics
V
AGND
- V
OUT
I
LIM
I
TH_FB
10V
27V
I
RSENSE
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相關代理商/技術參數 |
參數描述 |
|---|---|
| MAX5971AETI+ | 功能描述:熱插拔功率分布 IEEE 802.3af/at PSE Controller RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MAX5971AETI+T | 功能描述:熱插拔功率分布 IEEE 802.3af/at PSE Controller RoHS:否 制造商:Texas Instruments 產品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| MAX5971AETI+W | 制造商:Maxim Integrated Products 功能描述:IEEE802.3 AT PSE SWITCH - Rail/Tube |
| MAX5971AEVKIT | 功能描述:電源管理IC開發工具 RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| MAX5971AEVKIT+ | 制造商:Maxim Integrated Products 功能描述:PD INTERFACE CONTROLLER - Boxed Product (Development Kits) |
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