MP62170/MP62171 –CURRENT-LIMITED POWER DISTRIBUTION SWITCH
MP62170/MP62171 Rev.0.9 www.MonolithicPower.com 9
1/12/2010 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/MP62171
switches into to a constant-current mode (current
limit value). MP62170/MP62171 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/MP62171 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/
MP62171 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 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 over temperature of 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/MP62171 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.
