LM5068MM-3/NOPB National Semiconductor, LM5068MM-3/NOPB Datasheet - Page 14

• Manufacturer Part Number: LM5068MM-3/NOPB
• Description: IC CONTROLLER HOTSWAP -48V 8MSOP
• Manufacturer: National Semiconductor
• Type: Hot-Swap Controllerr

Specifications of LM5068MM-3/NOPB

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: -10 V ~ -90 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: Surface Mount
• Package / Case: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
• For Use With: LM5068EVAL - EVALUATION BOARD FOR LM5068
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LM5068MM-3; LM5068MM-3TR

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Sense Resistor (R
Capacitor (C
Mosfet (Q1) Selection
Applying Equation (5) and Equation (7) to Equation (2) gives
the TIMER capacitor value of:
Finally, the SOA curves of a prospective MOSFET are
checked using V
from equation Equation (6) and time of the current flow from
Equation (2).
Example: For: I
C
To account for tolerances of R
TIMER threshold voltage, the computed C
increased, for this example 50% was selected, therefore:
C
The maximum active current limiting value and duration are:
The N-channel MOSFET selection for use with the LM5068
controller in this example must be capable of sustaining
L
T
=100µF,
= 300nF • 1.5 = 450nF
L
IN (MAX)
=1A, V
T
) and N-Channel
, and I
DD
= 48V, V
SHORT-CIRCUIT (MAX)
s
), Timer
S
, C
L
DD (MAX)
, TIMER current and
(Continued)
T
value should be
= 100V and
calculated
(10)
(8)
(9)
14
V
condition. A device that meets the established criteria is the
Vishay - 5UB85N10-10.
External Sense Resistor
Precise current measurement depends on the accuracy of
the sense resistor (R
nection and close location of R
considered. Figure 4 demonstrates PCB layout for the Kelvin
sensing.
The R
is the normal maximum operating load.
DD
=100V and I
S
power rating should be greater than I
FIGURE 4. Sense Resistor Connections
(MAX)
S
=3A for 7.5ms in the worst case fault
). For the optimal results, Kelvin con-
S
to the LM5068 should be
2
L
*
R, where I
20078623
L