Datasheet

R
SENSE
+
Threshold Voltage
I
SENSE
+
0.045
3.5 A
+ 0.0128 W
I
MAX
+
Threshold Voltage
R
SENSE
+
0.055 V
12.87 mW
+ 4.27 A
TPS2363
SLUS680B –JANUARY 2006–REVISED JANUARY 2010 www.ti.com
Fault Threshold calculations
An over-current fault is determined by the voltage developed across a sense resistor. A small resistance,
typically less than tens of milliohms is placed in the slot current switch path. The voltage across the sense
resistor is input to a comparator that turns on when the voltage is greater than the current limit threshold.
The 3.3 V has a PCIExpress specification of 3.0 A for any connector width.
• With tolerances on the resistor and etch we limit the current to 3.5 A.
• The minimum current limit threshold for 3.3 V is 45 mV.
(use a 13-mΩ resistor)
Check the maximum current limit,
• A 1% resistor is 12.87 mΩ minimum.
• The Maximum current limit threshold is 55 mV.
Table 4. 3.3-V Sense Resistor Values
RESISTOR (mΩ) AVG CURRENT (A) MAX CURRENT (A)
+3.3 V 13 3.5 4.27
The 12-V sense resistor values table shows the recommended R
SENSE
values for the 12 V for the 1, 8, and 16
wide connectors.
Table 5. 12-V Sense Resistor Values
CONNECTOR WIDTH RESISTOR (mΩ) AVG CURRENT (A) MAX CURRENT (A)
1 50 0.9 1.11
4,8 20 2.1 2.78
16 10 4.4 5.56
16 graphics 8 5.5 6.94
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