參數(shù)資料
型號： MAX5921
廠商： Maxim Integrated Products, Inc.
元件分類： 基準電壓源/電流源
英文描述： -48V Hot-Swap Controllers with External Rsense and High Gate Pulldown Current
中文描述： -48V熱插拔控制器，外置RSENSE、提供較高的柵極下拉電流
文件頁數(shù)： 15/18頁
文件大?。?/td> 313K
代理商： MAX5921
M
-48V Hot-Swap Controllers with External
R
SENSE
and High Gate Pulldown Current
______________________________________________________________________________________
15
The lowest practical R
DS(ON)
, within budget constraints
and with values from 14m
to 540m
, are available at
100V breakdown.
Ensure that the temperature rise of Q1 junction is not
excessive at normal load current for the package select-
ed. Ensure that I
CB
current during voltage transients
does not exceed allowable transient-safe operating-area
limitations. This is determined from the SOA and tran-
sient-thermal-resistance curves in the Q1 manufacturer
’
s
data sheet.
Example 1:
I
LOAD
= 2.5A, efficiency = 98%, then V
DS
= 0.96V is
acceptable, or R
DS(ON)
≤
384m
at operating temper-
ature is acceptable. An IRL520NS 100V NMOS with
R
DS(ON)
≤
180m
and I
D(ON)
= 10A is available in
D
2
PAK. (A Vishay Siliconix SUD40N10-25 100V NMOS
with R
DS(ON)
≤
25m
and I
D(ON)
= 40A is available in
DPAK but may be more costly because of a larger die
size).
Using the IRL520NS, V
DS
≤
0.625V even at +80
°
C so effi-
ciency
≥
98.6% at 80
°
C. P
D
≤
1.56W and junction temper-
ature rise above case temperature would be 5
°
C due to
the package
θ
JC
= 3.1
°
C/W thermal resistance. Of
course, using the SUD40N10-25 will yield an efficiency
greater than 99.8% to compensate for the increased cost.
If I
CB
is set to twice I
LOAD
, or 5A, V
DS
momentarily dou-
bles to
≤
1.25V. If C
OUT
= 4000μF, transient-line input
voltage is
36V, the 5A charging-current pulse is:
Entering the data sheet transient-thermal-resistance
curves at 1ms provides a
θ
JC
= 0.9
°
C/W. P
D
= 6.25W,
so
t
JC
= 5.6
°
C. Clearly, this is not a problem.
Example 2:
I
LOAD
= 10A, efficiency = 98%, allowing V
DS
= 0.96V
but R
DS(ON)
≤
96m
. An IRF530 in a D
2
PAK exhibits
R
DS(ON)
≤
90m
at +25
°
C and
≤
135m
at +80
°
C.
Power dissipation is 9.6W at +25
°
C or 14.4W at +80
°
C.
Junction-to-case thermal resistance is 1.9W/
°
C, so the
junction temperature rise would be approximately 5
°
C
above the +25
°
C case temperature. For higher efficien-
cy, consider IRL540NS with R
DS(ON)
≤
44m
. This
allows
η
= 99%, P
D
≤
4.4W, and T
JC
= +4
°
C
(
θ
JC
= 1.1
°
C/W) at +25
°
C.
Thermal calculations for the transient condition yield
I
CB
= 20A, V
DS
= 1.8V, t = 0.5ms, transient
θ
JC
=
0.12
°
C/W, P
D
= 36W and
t
JC
= 4.3
°
C.
Layout Guidelines
Good thermal contact between the MAX5921/MAX5939
and the external MOSFET is essential for the thermal-
shutdown feature to operate effectively. Place the
MAX5921/MAX5939 as close as possible to the drain of
the external MOSFET and use wide circuit-board traces
for good heat transfer. See Figure 15 for an example of
recommended layout for Kelvin-sensing current
through a sense resistor on a PC board.
t
F x
5
V
A
ms
1
.
=
=
4000
1 25
μ
500
μ
s x 128
V
OL
V
SENSE
V
GATE
t
1
t
3H
t
5H
t
2L
t
4L
Figure 14. MAX5921A Overcurrent Fault Example
SENSE RESISTOR
HIGH-CURRENT PATH
MAX5921
MAX5939
SENSE V
EE
Figure 15. Recommended Layout for Kelvin-Sensing Current
Through Sense Resistor
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相關代理商/技術參數(shù)
參數(shù)描述
MAX5921AESA 功能描述:熱插拔功率分布 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
MAX5921AESA+ 功能描述:熱插拔功率分布 48V- Hot-Swap 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
MAX5921AESA+T 功能描述:熱插拔功率分布 48V- Hot-Swap 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
MAX5921AESA-T 功能描述:熱插拔功率分布 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
MAX5921AEVKIT 功能描述:熱插拔功率分布 Evaluation Kit for the MAX5920 MAX5921 MAX5939 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
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