Micrel, Inc.
MIC2587/MIC2587R
Pin Description (Continued)
Pin Number
7
8
Pin Name
SENSE
VCC
Pin Function
Circuit Breaker Sense Input: This pin is the (−) Kelvin sense connection for the output supply rail.
A low-valued resistor (RSENSE) between this pin and the VCC pin sets the circuit breaker’s
current-limit trip point. When the current-limit detector circuit is enabled (as well as the current
limit0020timer), while the FB pin voltage remains higher than 1V, the voltage across the sense
resistor (VCC − VSENSE) will be regulated to VTRIP (47mV, typically) to maintain a constant current
into the load. When the FB pin voltage is less than ≅ 0.5V, the circuit breaker trip voltage
decreases linearly to 12mV (typical) when the FB pin voltage is at 0V.
To disable the circuit breaker (and defeat all current-limit protections), the SENSE pin and the
VCC pin can be tied together.
Positive Supply Voltage Input: This pin is the positive supply input to the controller and the (+)
Kelvin sense connection for the output supply rail. The nominal operating voltage range for the
MIC2587 and the MIC2587R is +10V to +80V, and VCC can withstand input transients up to
+100V. An undervoltage lockout circuit holds the GATE pin low whenever the supply voltage to
the MIC2587 and the MIC2587R is less than the VUVH threshold.
January 24, 2013
5
Revision 2.0