LM5069_10 Datasheet, PDF (1/8 Pages) National Semiconductor (TI) – Output Voltage Clamping Using the LM5069 Hot Swap Controller

Output Voltage Clamping
Using the LM5069 Hot Swap
Controller
National Semiconductor
Application Note 2040
Dennis Morgan
March 15, 2010
The Issue
One of the many benefits of using the LM5069 Hot Swap
Controller, besides inrush current limiting and fault monitor-
ing, is that the controller supplies a voltage to the load that is
between defined limits. This feature prevents the load from
receiving a voltage less than what it is rated for (which could
result in erratic behavior), and prevents it from receiving a
voltage higher than what it is rated for, which could result in
overheating and/or damage. The voltage limits to the load are
set by the UVLO (Under-Voltage Lock Out) and OVLO (Over-
Voltage Lock Out) thresholds, which are set with external
resistors (R1-R3 in Figure 1).
While the OVLO function can be used to keep excessive volt-
ages at V_IN from reaching the load at V_OUT, a potential draw-
back to this method of over-voltage protection is that the
voltage at V_OUT is shut off for the duration of the over-voltage
condition. This can (and likely will) result in a shutdown of the
load circuitry, followed by a restart – an event which may in-
terrupt the normal operation of other associated circuitry.
FIGURE 1. LM5069 Basic Application Circuit
30119201
© 2010 National Semiconductor Corporation 301192
www.national.com