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参数资料
| 型号： | MAX5952CEAX+T |
| 厂商： | Maxim Integrated |
| 文件页数： | 19/50页 |
| 文件大小： | 1006K |
| 描述： | IC PSE CTRLR FOR POE 36-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1,000 |
| 类型： | 以太网供电控制器（PoE） |
| 应用： | 远程外设（工业控制，相机，数据访问） |
| 内部开关： | 无 |
| 工作温度： | -40°C ~ 85°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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High-Power, Quad, PSE Controller
for Power-Over-Ethernet
______________________________________________________________________________________ 19
Overcurrent Protection
A sense resistor R
S
connected between SENSE_ and
V
EE
monitors the load current. Under normal operating
conditions, the voltage across R
S
(V
RS
) never exceeds
the threshold V
SU_LIM
. If V
RS
exceeds V
SU_LIM
, an
internal current-limiting circuit regulates the GATE volt-
age, limiting the current to I
LIM
= V
SU_LIM
/ R
S
. During
transient conditions, if V
RS
exceeds V
SU_LIM
by more
than 1V, a fast pulldown circuit activates to quickly
recover from the current overshoot. During startup, if
the current-limit condition persists, when the startup
timer, t
START
, times out, the port shuts off, and the
STRT_FLT_ bit is set. In the normal powered state, the
MAX5952 checks for overcurrent conditions as deter-
mined by V
FLT_LIM
= ~88% of V
SU_LIM
. The t
FAULT
counter sets the maximum allowed continuous overcur-
rent period. The t
FAULT
counter increases when V
RS
exceeds V
FLT_LIM
and decreases at a slower pace
when V
RS
drops below V
FLT_LIM
. A slower decrement
for the t
FAULT
counter allows for detecting repeated
short-duration overcurrents. When the counter reaches
the t
FAULT
limit, the MAX5952 powers off the port and
asserts the IMAX_FLT_ bit. For a continuous overstress,
a fault latches exactly after a period of t
FAULT
. V
SU_LIM
is programmable through the ICUT registers R2Ah[6:4],
R2Ah[2:0], R2Bh[6:4], R2Bh[2:0], and the IVEE bits in
register R29h[1:0]. See the High-Power Mode section
for more information on the ICUT register.
After power-off due to an overcurrent fault, and if the
RSTR_EN bit is set, the t
FAULT
timer is not immediately
reset but starts decrementing at the same slower pace.
The MAX5952 allows the port to be powered on only
when the t
FAULT
counter is at zero. This feature sets an
automatic duty-cycle protection to the external MOS-
FET avoiding overheating.
The MAX5952 continuously flags when the current
exceeds the maximum current allowed for the class as
indicated in the CLASS status register. When class
overcurrent occurs, the MAX5952 sets the IVC bit in
register R09h.
ICUT Register and High-Power Mode
ICUT Register
The ICUT register determines the maximum current lim-
its allowed for each port of the MAX5952. The 3 ICUT
bits (R2Ah[6:4], R2Ah[2:0], R2Bh[6:4], and R2Bh[2:0])
allow programming of the current-limit and overcurrent
thresholds in excess of the IEEE standard limit (see
Tables 34a, 34b, and 34c). The ICUT registers can be
written to directly through the I
2
C interface when
CL_DISC (R17h[2]) is set to 0 (see Table 3). In this
case, the current limit of the port is configured regard-
less of the status of the classification.
By setting the CL_DISC bit to 1, the MAX5952 automati-
cally sets the ICUT register based upon the classifica-
tion result of the port. See Table 3 and the Register
Map and Description section.
Figure 2. PGOOD Timing
PGOOD
POK
t
PGOOD
Table 3. Automatic ICUT Programming
CL_DISC
PORT
CLASSIFICATION
RESULT
RESULTING ICUT
REGISTER BITS
0
Any
User programmed
1
1
ICUT = 110
1
2
ICUT = 111
1
0, 3
ICUT = 000
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX5952CUAX+ | 功能描述:热插拔功率分布 Quad PSE Controller for POE 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 |
| MAX5952CUAX+T | 功能描述:热插拔功率分布 Quad PSE Controller for POE 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 |
| MAX5952DEAX+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX5952DEAX+T | 制造商:Maxim Integrated Products 功能描述:HIGH-POWER QUAD PSE CONTROLLER FOR - Tape and Reel |
| MAX5952DUAX+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
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