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參數(shù)資料
| 型號： | MAX5922AEUI+ |
| 廠商： | Maxim Integrated |
| 文件頁數(shù)： | 17/21頁 |
| 文件大?。?/td> | 437K |
| 描述： | IC NETWORK PWR SW +48V 28-TSSOP |
| 產(chǎn)品培訓模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標準包裝： | 50 |
| 類型： | 以太網(wǎng)供電開關（PoE） |
| 應用： | 遠程外設（工業(yè)控制，相機，數(shù)據(jù)訪問） |
| 內(nèi)部開關： | 是 |
| 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-TSSOP（0.173"，4.40mm 寬） |
| 供應商設備封裝： | 28-TSSOP |
| 包裝： | 管件 |
| 產(chǎn)品目錄頁面： | 1411 (CN2011-ZH PDF) |
+48V, Single-Port Network Power Switch
For Power-Over-LAN
______________________________________________________________________________________ 17
Digital Logic
V
DIG
is the input supply for the internal logic circuitry.
The logic input thresholds of EN, LATCH, CLASS, DCA
(MAX5922A), DET_DIS (MAX5922B/MAX5922C), and
ZC_EN are CMOS compatible and are determined by
the voltage at V
DIG
which can range from 1.65V to
5.5V. The POK, ZC, CL0, CL1, CL2, and FAULT outputs
are open drain. V
DIG
and all logic inputs and outputs
are referenced to DGND. DGND is not connected to
AGND internally and must be connected externally at a
single point in the system to AGND. The maximum
allowable difference in the voltage between DGND and
AGND is ?V.
Enable (EN)
EN is a logic input to enable the MAX5922. Bringing EN
low halts all operations and turns off the internal power
MOSFET. When EN is high and the input voltage is
above the UVLO threshold, the MAX5922 begins oper-
ating. Enable is also used to unlatch the part after a
latched fault condition. This is done by toggling EN low
and high again after a fault condition.
Overcurrent Protection
The MAX5922 provides a sophisticated overcurrent
protection circuitry to ensure the devices robustness
under output-current transient and current fault condi-
tions. The current protection circuitry employs a con-
stant current limit, a current foldback, and an
overcurrent timeout. The device monitors the voltage
drop, V
SENSE
(V
SENSE
= V
IN
- V
DRAIN
) to determine the
load current.
Constant Current Limit
The MAX5922 monitors V
SENSE
at all times during
power mode and regulates the current through the
power MOSFET as necessary to keep V
SENSE
(max) to
the current-limit sense voltage (V
ILIM
= 212mV). The
load-current limit, I
LIM
, is programmed by the current-
sense resistor, R
SENSE
, connected from IN to DRAIN
(I
LIM
= V
ILIM
/R
SENSE
). When the load current is less
than I
LIM
, the MOSFET is fully on. When the load is try-
ing to draw more than I
LIM
, the OUT pin works like a
constant current source, limiting the output current to
I
LIM
. If I
OUT
is at I
LIM
for greater than the current-limit
timeout, a current-limit fault is generated and the power
MOSFET is turned off (see the Overcurrent Timeout and
Fault Management sections).
Current Foldback
While in current-limit condition, the voltage at the OUT
pin drops. As the load resistance reduces (more load-
ing), the output voltage reduces accordingly to main-
tain a constant load current. The power dissipation in
the power MOSFET is (V
DRAIN
- V
OUT
) ?I
LIM
. As the
output voltage drops lower, more power is dissipated
across the power MOSFET. To reduce this power dissi-
pation, the MAX5922 offers a current foldback feature
where it linearly reduces the V
ILIM
value when V
OUT
drops below the OUT current-limit foldback voltage
(V
FBSTOP
= 18V). Figure 8 illustrates this current fold-
back limit behavior.
Overcurrent Timeout
The MAX5922 keeps track of the time it is in current limit.
An internal digital counter begins incrementing its count
at 1count/ms when V
SENSE
exceeds its limit (either V
ILIM
or V
ILIM
foldback in foldback mode). The counter is reset
to zero if the current falls back below the current limit.
When the cumulative count reaches 60, an overcurrent
fault is generated. After an overcurrent fault condition, the
switch is turned off and the FAULT signal goes low (see
Figure 9).
MAX5922
IN
UVLO
AGND_S
R1
R2
V
IN
= 32V TO 60V
Figure 7. Setting Undervoltage Lockout with an External
Resistive-Divider
V
ILM
V
ILM
/3
V
FBSTART
(2V)
V
FBSTOP
(18V)
V
OUT
(V)
Figure 8. Current Foldback Characteristic
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX5922AEUI+ | 功能描述:熱插拔功率分布 48V Single-Port Network Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)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 |
| MAX5922AEUI+T | 功能描述:熱插拔功率分布 48V Single-Port Network Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)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 |
| MAX5922AEUI-T | 功能描述:熱插拔功率分布 RoHS:否 制造商:Texas Instruments 產(chǎn)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 |
| MAX5922BEUI | 功能描述:熱插拔功率分布 RoHS:否 制造商:Texas Instruments 產(chǎn)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 |
| MAX5922BEUI+ | 功能描述:熱插拔功率分布 48V Single-Port Network Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)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 |
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