January 2005

15

MIC2012/2072

MIC2012

Micrel

dead short on the output.

Fault Status Output

The FAULT signal is an active-low output with an open-drain

or weak pull-up configuration. FAULT is asserted (active-low)

when either an overcurrent or thermal shutdown condition

occurs. In the case of an overcurrent condition, FAULT will

be asserted only after the flag response delay time, t

elapsed. This ensures that FAULT is asserted only upon valid

overcurrent conditions and that erroneous error reporting is

eliminated. For example, false overcurrent conditions can

occur during hot-plug events when a highly capacitive load

is connected and causes a high transient inrush current that

exceeds the current-limit threshold. The FAULT response

delay time t

Undervoltage Lockout

Undervoltage lockout (UVLO) prevents the output MOSFET

from turning on until the AUX input exceeds approximately

3.5V. UVLO ensures that the output MOSFETs remain off

to prevent high transient inrush current due to stray or bulk

load capacitance. This helps to ensure that the power supply

EN

(MIC2010-2)

Overcurrent Fault

Thermal Shutdown

Reached

FAULT

Figure 6. MIC2012 System Timing

EN

(MIC2070-2)

Overcurrent Fault

Load Removed–

Output Reset

FAULT

Figure 7. MIC2072 System Timing—

Output Resets When Load is Removed