MP62260/MP62261 – CURRENT-LIMITED POWER DISTRIBUTION SWITCH
MP62260/MP62261 Rev. 0.9 www.MonolithicPower.com 9
4/6/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
DETAILED DESCRIPTION
Over Current
When the load exceeds trip current (minimum
threshold current triggering constant-current
mode) or a short is present, MP62260/MP62261
switches into to a constant-current mode (current
limit value). MP62260/MP62261 will be shutdown
only if the over current condition stays long
enough to trigger thermal protection.
Trigger over current protection for different
overload conditions occurring in applications:
1) The output has been shorted or overloaded
before the device is enabled or input applied.
MP62260/MP62261 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
MP62260/MP62261 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.
Thermal Protection
The purpose of thermal protection is to prevent
damage in the IC by allowing exceptive current to
flow and heating the junction. The die
temperature is internally monitored until the
thermal limit is reached. Once this temperature is
reached, the switch will turn off and allow the
chip to cool. The switch has a built-in hysteresis.
Under-voltage Lockout (UVLO)
This circuit is used to monitor the input voltage to
ensure that the MP62260/MP62261 is operating
correctly.
This UVLO circuit also ensures that is no
operation until the input voltage reaches the
minimum spec.
Enable
The logic pin disables the switch to reduce
overall supply current. Once the EN pin reaches
EN threshold, the MP62260/MP62261 is enabled.
