MP62180/MP62181 –CURRENT-LIMITED POWER DISTRIBUTION SWITCH
MP62180_MP62181 Rev. 0.9 www.MonolithicPower.com 7
2/23/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
FUNCTION BLOCK DIAGRAM
Vref
Deglitch
Logic
Charge
Pump
GND
*: EN is active high for MP62181; EN is active low for MP62180
Thermal
Sense
UVLO
IN
EN*
FLAG
OUT
Current
Sense
AMP
--
+
+
--
Figure2—Function Block Diagram
DETAILED DESCRIPTION
Over Current
When the load exceeds trip current (minimum
threshold current triggering constant-current
mode) or a short is present, MP62180/MP62181
switches into to a constant-current mode (current
limit value). MP62180/MP62181 will be shutdown
only if the overcurrent condition stays long
enough to trigger thermal protection.
Trigger overcurrent protection for different
overload conditions occurring in applications:
1) The output has been shorted or overloaded
before the device is enabled or input applied.
MP62180/MP62181 detects the short or
overload and immediately switches into a
constant-current mode.
2) A short or an overload occurs after the device
is enabled. After the current-limit circuit has
been tripped (reached the trip current
threshold), the device switches into constant-
current mode. However, high current may
flow for a short period of time before the
current-limit circuit can react.
3) Output current has been gradually increased
beyond the recommended operating current.
The load current rises until the trip current
threshold is reached or until the thermal limit
of the device is exceeded. The
MP62180/MP62181 is capable of delivering
current up to the trip current threshold without
damaging the device. Once the trip threshold
has been reached, the device switches into
its constant-current mode.
Flag Response
The FLAG pin is an open drain configuration.
This FAULT will report a fail mode after an 8ms
deglitch timeout. This is used to ensure that no
false fault signals are reported. This internal
deglitch circuit eliminates the need for extend
components. The FLAG pin is not deglitched
during an over temp. or a voltage lockout.
