MP62170-1/MP62171-1 –CURRENT-LIMITED POWER DISTRIBUTION SWITCH
MP62170-1/MP62171-1 Rev.1.0 www.MonolithicPower.com 9
10/26/2010 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, MP62170-
1/MP62171-1 switches into to a constant-current
mode (current limit value). MP62170-1/MP62171-
1 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.
MP62170-1/MP62171-1 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 MP62170-1/
MP62171-1 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 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 MP62170-1/MP62171-1 is
operating correctly. This UVLO circuit also
ensures that there is no operation until the input
voltage reaches the minimum spec.
Enable
The logic pin disables the chip to reduce the
supply current. The device will operate once the
enable signal reaches the appropriate level. The
input is compatible with both COMS and TTL.
Output Discharge
The part involves a discharge function that
provides a resistive discharge path for the
external output capacitor. The function will be
active when the part is disabled (Input voltage is
under UVLO or enable is deasserted) and it will
be done in a very limited time.
