MP2676 –LI-ION CHARGER PROTECTION IC WITH INTEGRATED P-MOSFET
MP2676 Rev. 0.91 www.MonolithicPower.com 8
12/7/2010 MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
OPERATION
The MP2676 is a highly integrated circuit
designed to provide complete Li-ion battery
charger protection against input over voltage,
input over current and battery over voltage. The
IC continuously monitors the input voltage, the
input current and the battery voltage, when any
of the monitored parameters exceeds its
threshold, the IC immediately turns off the
internal N-channel MOSFET to remove the
power from the charge system before any
damage occurs. Moreover, all protections also
have blanking times against false triggering due
to voltage spikes or current transients. The IC
also features thermal shutdown protection, if
the temperature exceeds 140ºC, MP2676 will
turn off the internal MOSFET bridging ACIN and
CHRIN.
MP2676 integrates a P-channel MOSFET with
the body diode reverse protection to replace the
external P-channel MOSFET and block diode
for charge function of portable devices with
PMIC (Power Management IC).
Power Up
The MP2676 has a power-on reset (POR)
threshold of 2.65V with a built-in hysteresis of
130mV. When the input voltage is below the
POR threshold, the internal N-channel
MOSFET is off. The IC resets itself and waits
for about 10ms after the input voltage exceeds
the POR threshold, then, if the input voltage
and battery voltage are safe, the IC begins to
soft-start the internal N-channel MOSFET. The
10ms delay allows any transient at the input
during a hot insertion of the power supply to
settle down before the IC starts to operate. The
soft-start slowly turns on the N-channel
MOSFET to reduce the inrush current as well
as the input voltage drop during the transition.
Input Over-voltage Protection (OVP)
The input voltage is continuously monitored by
the internal comparator CP1 in the block
diagram (Figure 1), the OVP threshold is set by
an internal resistive divider and an accurate
reference generated by the IC itself. The
protection threshold is set to 6V. When the
input voltage exceeds the threshold, the CP1
outputs a logic signal to turn off the N-channel
MOSFET within 1µs to prevent the high input
voltage from damaging the electronics in the
handheld system. The hysteresis of the input
OVP threshold is given in the Electrical
Characteristic. When the input over-voltage
condition is removed, the N-channel MOSFET
is turned on again by running through the soft-
start. Because of the 10ms delay before the
soft-start, the output is never enabled if the
input rises above the OVP threshold within
10ms.
Battery Over-voltage Protection (BOVP)
The battery voltage OVP threshold is internally
set to 4.35V, and the threshold has 240mV
built-in hysteresis. When the battery voltage
exceeds the battery OVP threshold, the internal
comparator CP2 has a built-in 200µs blanking
time to prevent any transient voltages from
triggering the BOVP. If the BOVP situation still
exists after the blanking time, the N-channel
MOSFET is turned off. There is an internal 4-bit
binary counter monitoring the occurrences of
the BOVP event. If the BOVP event occurs 16
times, the N-channel MOSFET is turned off
permanently. Recycling the input power will
reset the counter and restart the MP2676.
Over-current Protection (OCP)
The current through the N-channel MOSFET is
limited to prevent charging the battery with an
excessive current. The current limit threshold is
preset to 1.6A. The OCP comparator CP3 has a
built-in 180µs delay to prevent false triggering
by transient signals. When OCP happened,
VOUT shuts down and takes 60ms delay to soft
start as the OCP condition is removed. The
OCP function also has a 4-bit binary counter
that accumulates the occurrences of OCP
event. When the total count reaches 16, the N-
channel MOSFET is turned off permanently
unless the input power is recycled.
Thermal Protection
The MP2676 monitors its own die temperature
to prevent thermal failures. When the internal
temperature reaches 140°C, the internal N-
channel MOSFET is turned off. The IC does not
resume operation until the internal temperature
drops below 120°C
