-48V Hot-Swap Controllers with External
R
SENSE
and High Gate Pulldown Current
14   ______________________________________________________________________________________
Component Selection Procedure:
" Determine load capacitance:
C
L
= C2 + C3 + module input capacitance
"  Determine load current, I
LOAD
.
" Select circuit-breaker current, for example:
I
CB
= 2 x I
LOAD
" Calculate R
SENSE
:
Realize that I
CB
varies ?0% due to trip-voltage tol-
erance.
" Set allowable inrush current:
"  Determine value of C2:
"  Calculate value of C1:
"  Determine value of R3:
"  Set R2 = 10&.
"  If an optocoupler is utilized as in Figure 14, deter-
mine the LED series resistor:
Although the suggested optocoupler is not specified for
operation below 5mA, its performance is adequate for
36V temporary low-line voltage where LED current
would then be H2.2mA to 3.7mA. If R7 is set as high as
51k&, optocoupler operation should be verified over
the expected temperature and input voltage range to
ensure suitable operation when LED current H0.9mA for
48V input and H0.7mA for 36V input.
If input transients are expected to momentarily raise the
input voltage to >100V, select an input transient-voltage-
suppression diode (TVS) to limit maximum voltage on the
MAX5921/MAX5939 to less than 100V. A suitable device
is the Diodes Inc. SMAT70A telecom-specific TVS.
Select Q1 to meet supply voltage, load current, efficien-
cy, and Q1 package power-dissipation requirements:
BV
DSS
e 100V
I
D(ON)
e 3 x I
LOAD
DPAK, D
2
PAK, or TO-220AB
R
V
V
I
mA
IN NOMINAL
LED
7
2
3
5
  
(
)
=
d
d
R
s
C
3
150
2
=
?/DIV>
C
C
C
x
V
V
V
gd
IN MAX
GS TH
GS TH
1
2
=
+
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
(
)
(
)
(    )
(    )
C
A x C
I
L
INR    H
2
45
=
?/DIV>
I
x
mV
R
I
or
I
I
x I
INRUSH
SENSE
LOAD
INRUSH
LOAD
CB MIN
d
+
d
0 8
40
0 8
.
.
(
)
R
mV
I
SENSE
B
=
50
MAX5921A
MAX5921E
MAX5939A
MAX5939E
V
EE
OV
UV
SENSE
GATE
DRAIN
PWRGD
V
DD
GND
-48V
C3
100礔
100V
C2
15nF
100V
R3
1k&
5%
R2
10&
5%
Q1
IRF530
R1
0.02&
5%
R4
549k&
1%
R5
6.49k&
1%
R6
10k&
1%
PWRGD
*DIODES INC. SMAT70A
R7
51k&
5%
-48V RTN
(SHORT PIN)
*
Figure 13. Using PWRGD to Drive an Optoisolator
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
MAX5939EESA+ |
功能描述:熱插拔功率分布 48V- Hot-Swap Controller 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(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MAX5939EESA+T |
功能描述:熱插拔功率分布 48V- Hot-Swap Controller 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(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MAX5939EESA-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(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MAX5939FESA |
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(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
MAX5939FESA+ |
功能描述:熱插拔功率分布 48V- Hot-Swap Controller 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(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
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