ADM1192

Rev. 0 | Page 16 of 20

When the output of the SETV comparator asserts, this tells the

ALERT block to begin charging the external TIMER capacitor

with a 60 μA charging current. When the voltage on the TIMER

capacitor reaches 1 V, the charging cycle is complete. The ALERT

output then asserts (goes high). Different values of TIMER

capacitor generate different time delays between current faults

occurring and the ALERT output asserting. When using the

ALERT output to implement a hot swap circuit, the TIMER

capacitor should be chosen to generate a large enough startup

delay to allow the maximum inrush current to completely

charge up the load without tripping an ALERT fault.

KELVIN SENSE RESISTOR CONNECTION

When using a low value sense resistor for high current measure-

ment, the problem of parasitic series resistance can arise. The

lead resistance can be a substantial fraction of the rated resistance,

making the total resistance a function of lead length.

This problem can be avoided by using a Kelvin sense connection.

This type of connection separates the current path through the

resistor and the voltage drop across the resistor. Figure 30 shows

the correct way to connect the sense resistor between the VCC

pin and the SENSE pin of the ADM1192.

SENSE RESISTOR

KELVIN SENSE TRACES

VCC

SENSE

ADM1192

CURRENT

FLOW FROM

SUPPLY

CURRENT

FLOW TO

LOAD

Figure 30. Kelvin Sense Connections