MAX5920 Maxim, MAX5920 Datasheet - Page 16

• Manufacturer Part Number: MAX5920
• Description: -48V Hot-Swap Controller with External RSENSE
• Manufacturer: Maxim

If I
bles to ≤ 1.25V. If C
voltage is ∆36V, the 5A charging-current pulse is:
Entering the data sheet transient-thermal-resistance
curves at 1ms provides a θJC = 0.9°C/W. P
so ∆t
Example 2:
I
but R
R
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
allows η = 99%, P
1.1°C/W) at +25°C.
Thermal calculations for the transient condition yield
I
0.12°C/W, P
-48V Hot-Swap Controller
with External R
16
LOAD
CB
DS(ON)
CB
= 20A, V
JC
______________________________________________________________________________________
is set to twice I
DS(ON)
= 10A, efficiency = 98%, allowing V
= 5.6°C. Clearly, this is not a problem.
≤ 90mΩ at +25°C and ≤ 135mΩ at +80°C.
D
MAX5920AESA
MAX5920BESA
≤ 96mΩ. An IRF530 in a D
= 36W and ∆t
DS
t
=
PART
= 1.8V, t = 0.5ms, transient θ
4000
D
LOAD
OUT
≤ 4.4W, and T
µ
F x
5
= 4000µF, transient-line input
A
, or 5A, V
JC
1 25
.
= 4.3°C.
V
DS(ON)
=
DS
1
JC
ms
SENSE
momentarily dou-
= +4°C (θ
≤ 44mΩ. This
2
PAK exhibits
DS
D
= 6.25W,
= 0.96V
Active high (PWRGD)
PWRGD POLARITY
Active low (PWRGD)
JC
JC
=
=
Good thermal contact between the MAX5920A/
MAX5920B and the external MOSFET is essential for the
thermal-shutdown feature to operate effectively. Place
the MAX5920A/MAX5920B as close as possible to the
drain of the external MOSFET and use wide circuit-board
traces for good heat transfer (see Figure 15).
Figure 15. Recommended Layout for Kelvin-Sensing Current
Through Sense Resistor
MAX5920A
MAX5920B
HIGH-CURRENT PATH
SENSE V
FAULT MANAGEMENT
EE
Selector Guide
Layout Guidelines
Latched
Latched
SENSE RESISTOR