LM5060Q1 National Semiconductor Corporation, LM5060Q1 Datasheet - Page 20

• Manufacturer Part Number: LM5060Q1
• Description: High-side Protection Controller With Low Quiescent Current
• Manufacturer: National Semiconductor Corporation

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REVERSE POLARITY PROTECTION WITH A RESISTOR
An alternative to using external diodes to protect the LM5060
OUT pin in the reverse polarity input condition is a resistor in
series with the OUT pin. Adding an OUT pin resistor may re-
quire modification of the resistor in series with the SENSE pin.
A resistor in series with the OUT pin will limit the current
through the internal zener diode between OUT and GATE as
When calculating the minimum R
the current into the OUT pin, the internal current sources of
8 µA and 16 µA may be neglected. The following formulas can
be used to calculate the resistor value R
essary to keep the I
Case A for situations where V
situation is present. See
voltage at the SENSE pin can roughly be assumed to be 0.0V
due to the internal diode from the SENSE pin to GND.
FIGURE 14. Application with Reverse Polarity Protection with Diodes for OUT Pin Protection
O
current to less than 4 mA.
Figure
FIGURE 15. Current Limiting Resistor for Negative SENSE Condition
OUT
15. V
O
> V
resistor required to limit
IN
IN
and reverse polarity
is negative, but the
O(MIN)
which is nec-
20
well as through the diode between OUT and SENSE. The
value of these resistors should be calculated to limit the cur-
rent through the diode across the input terminals of the V
fault comparator to be no more than 4 mA.
the internal circuitry relevant for calculating the values of the
resistor R
pin to 4 mA.
In this case, V
so that reverse current through the SENSE pin does not ex-
ceed 25 mA.
O
in the OUT path to limit the current into the OUT
IN
also has to be limited to a negative voltage
30104243
Figure 15
30104242
shows
DS