MP5013A – 5 V, 1 A-5 A PROGRAMMABLE CURRENT LIMIT SWITCH
MP5013A Rev. 1.0 www.MonolithicPower.com 9
6/18/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
OPERATION
The MP5013A limits the inrush current to the
load when a circuit card connects to a live
backplane power source, thereby limiting the
backplane’s voltage drop and the dv/dt of the
voltage to the load. It offers an integrated solution
to monitor the input voltage, output voltage,
output current, and die temperature, eliminating
the external current-sense power resistor, power
MOSFET, and thermal sensor.
Under-Voltage Lockout Operation
If the supply (input) is below the UVLO threshold,
the output is disabled, and the ENABLE/FAULT
line is driven low.
When the supply rises above the UVLO threshold,
the output is enabled, and ENABLE/FAULT is
pulled high through a 25 A current source
without an external pull-up resistor. The pull-up
voltage is limited to 4.95 V.
Output Over-Voltage Protection (OVP)
If the input voltage exceeds the over-voltage
protection (OVP) threshold, the output is clamped
at 5.7 V (typically).
Current Limiting
When the chip is active, if the load reaches the
over-current protection (OCP) threshold (trip
current), or a short is present, the part switches
to constant-current mode (hold current). The chip
shuts down only if the over-current condition
eventually triggers thermal protection. However,
when the part is powered up by VCC or EN, the
load current should be less than the hold current.
Otherwise, the part cannot be turned on fully.
In a typical application with a current-limiting
resistor of 22 , the trip current is 5 A, and the
hold current is 2.8 A. If the device is in normal
operation and passing 2 A, it will only need to
dissipate 144 mW with the low on resistance of
36 m. For a package dissipation of 100°C/W,
the temperature rise is +14°C. Given a 25°C
ambient temperature, the typical package
temperature is 39°C.
The MP5013A requires a heat sink during
constant-current mode (e.g., from a short circuit)
to prevent an unwanted shutdown. (During a
short-circuit condition, the chip must dissipate the
power from a 5 V drop.) Without an additional
heat dissipation at 100°C/W, the temperature will
exceed the thermal threshold (+175°C), and the
MP5013A will shut down to force the temperature
to drop.
Thermal Protection
If the temperature exceeds the thermal threshold,
the MP5013A disables its output and drives the
ENABLE/FAULT line to the middle (mid) level
(see the following “ENABLE/FAULT” section for
more information). The thermal fault condition is
latched, and the part will remain in a latched-off
state until the power is re-started, or ENABLE/
FAULT is re-set.
ENABLE/FAULT
ENABLE/FAULT is a bi-directional, three-level
I/O with a weak pull-up current (25 A, typically).
The three levels are low, mid, and high. It
functions to enable/disable the part and to relay
fault information.
ENABLE/FAULT as an input:
1. Low and mid disable the part.
2. Low, in addition to disabling the part,
clears the fault flag.
3. High enables the part (if the fault flag is
clear).
ENABLE/FAULT as an output:
1. The pull-up current will allow a “wired
nor” pull-up to enable the part (if not
overridden).
2. An under-voltage condition will cause a
low on ENABLE/FAULT and will clear
the fault flag.
3. A thermal fault will set a mid on the
ENABLE/FAULT and will set the fault
flag.
