Datasheet

MIC2025/2075 Micrel, Inc.
MIC2025/2075 10 June 2010
Short-Circuit Applied to Enabled Output
When a heavy load or short-circuit is applied, a large transient
current may ow until the current-limit circuitry responds. Once
this occurs the device limits current to less than the short-cir-
cuit current limit specication. See the Short-Circuit Transient
Response graph under Functional Characteristics.
Current-Limit Response—Ramped Load
The MIC2025/75 current-limit prole exhibits a small foldback
effect of about 200mA. Once this current-limit threshold is
exceeded the device switches into a constant current mode.
It is important to note that the device will supply current until
the current-limit threshold is exceeded. See the Current-Limit
Response graph under Functional Characteristics.
Fault Flag
The FLG signal is an N-channel open-drain MOSFET output.
FLG is asserted (active-low) when either an overcurrent
or thermal shutdown condition occurs. In the case where
an overcurrent condition occurs, FLG will be asserted only
after the ag response delay time, t
D
, has elapsed. This
ensures that FLG 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 FLG response delay time t
D
is
typically 3ms.
Undervoltage Lockout
Undervoltage lockout (UVLO) prevents the output MOS-
FET from turning on until V
IN
exceeds approximately 2.5V.
Undervoltage detection functions only when the switch is
enabled.
V
EN
V
OUT
I
OUT
Short-Circuit Fault
Thermal Shutdown
Reached
Load Removed
(Output Reset)
V
FLG
I
LIMIT
I
DC
t
D
Figure 1. MIC2075-2 Timing: Output Reset by Removing Load
V
EN
V
OUT
I
OUT
Short-Circuit Fault
Thermal Shutdown
Reached
Load/Fault
Removed
V
FLG
I
DC
I
LIMIT
t
D
Figure 2. MIC2025-2 Timing