Data Sheet

MP2636 –3.0A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 3.0A BOOST
MP2636 Rev.1.01 www.MonolithicPower.com 31
9/16/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
Integrated Over Current Protection and Over
Voltage Protection for Pass-through Path
The MP2636 has an integrated IN-to-SYS pass-
through path to allow direct connection of the
input voltage to the system even if the charging is
disabled. Based on the above, the MP2636
continuously monitors the input current and
voltage. In the event of an input OC limit or input
UV limit, the charge current will be reduced to
ensure the priority of the system requirement.
In addition, the MP2636 also features input over
current and voltage protection for the IN to SYS
pass-through path.
Input over-current protection (OCP):
The MP2636 implements input over-current
protection in 3 different ways:
a) When the total input current exceeds input
over-current threshold I
IN_OCP
, which is 125%
of the input current limit threshold I
IN_LMT
set by
R
ILIM
, Q2 is controlled linearly to regulate the
input current.
b) When the current reaches input over-current
shutdown threshold I
INOC_SHDN
(140% of the
I
IN_LMT
) after a 120µs blanking time, Q2 will be
turned off, and then restarting after 100ms
recovery time.
c) When the input current exceeds fast off
threshold (preset at 7A), both Q1 and Q2 are
turned off immediately, and then restarting
after 100ms recovery time.
Input over-voltage protection (OVP):
The MP2636 has a preset 6V input over voltage
threshold, once the input voltage exceeds the
OVP threshold, the IN-to-SYS pass-through path
will be bridged off to prevent the over voltage
event happening at SYS side when plugging in a
wrong adapter.
Figure 12: IN-to-SYS Pass-through Path
Charge Current Setting
The external sense resistors, RS1, and R
ISET
,
program the battery charge current I
CHG
. Select
R
ISET
based on RS1:
CHG
ISET
2400
I(A)
R(k)RS1(m)
=
Ω× Ω
(6)
Battery Current Analog Output
The MP2636 has an IB pin to report the real-time
battery current in both charge and boost mode.
The voltage at IB is a fraction of the battery
current given RS1 is 20m.
Boost Mode:
IB BATT
V(V) I (A) 0.4(R)
=
×
(7)
Charge Mode:
IB CHG
V (V) I (A) 0.36(R)
=
×
(8)
Battery Short Protection
When battery voltage is lower than the TC-to-CC
threshold, Q3 peak current limit will be reduced
by half (please refer to the block diagram).
Furthermore PWM switching frequency will also
be reduced when V
BATT
drops 60% below of the
charge-full voltage.
Thermal Foldback Function
The MP2636 implements thermal protection to
prevent the thermal damage to the IC and the
surrounding components. An internal thermal
sense circuit and feedback loop automatically
decreases the programmed charge current when
the die-temperature reaches 120ºC. This function
is called the charge-current-thermal fold-back.
Not only this function protects against thermal
damage, it can also set the charge current based
on requirements rather than worst-case
conditions while ensuring safe operation.
Furthermore, the part includes thermal shutdown
protection where the ceases charging if the
junction temperature rises to 150ºC.
Constant-Off-Time Control for Large Duty
Charging Operation
The MP2636 has an internal 600kHz frequency
oscillator for the switching frequency. Unlike the
traditional fixed frequency, the MP2636 features
a constant-off-time control to support constant-
current charge even when the input voltage is
very close to the battery voltage. As shown in the