Data Sheet
MP2636 –3.0A SINGLE CELL SW MODE BATTERY CHARGER WITH PPM AND 3.0A BOOST
MP2636 Rev.1.01 www.MonolithicPower.com 30
9/16/2015 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2015 MPS. All Rights Reserved.
Timer Operation
The MP2636 uses an internal timer to terminate
the charging. The timer remains active during the
charging process. An external capacitor between
TMR and GND programs the charge cycle
duration.
If charging remains in TC mode beyond the
trickle-charge time,
TC_TMR
, the charging will
terminate. The following equation determines the
length of the trickle-charge period:
4
TMR
TC _ TMR
TC
4.5 10 1.6(V) C ( F)
(s)
1.25 I (A) RS1(m ) 2( A)
×× × μ
τ=
×× Ω+μ
(1)
The maximum total charge time is:
6
TMR
TOTAL_TMR
CHG
3.4 10 1.6(V) C ( F)
(s)
1.25 I (A) RS1(m ) 2( A)
×× × μ
τ=
××Ω+μ
(2)
Negative Thermal Coefficient (NTC) Input
The MP2636 has a built-in NTC resistance
window comparator, which allows MP2636 to
monitor the battery temperature via the battery-
integrated thermistor. Connect an appropriate
resistor from V
SYS
to the NTC pin and connect the
thermistor from the NTC pin to GND. The resistor
divider determines the NTC voltage depending
on the battery temperature. If the NTC voltage
falls outside of the NTC window, the MP2636
stops charging. The charger will then restart if the
temperature goes back into NTC window range.
During the NTC fault, the charge timer is
suspended.
Input Voltage Range for Different Operating
Mode
MP2636 operates in different mode based on the
state of the input. (see Table 1)
Charge Mode: A resistor divider connected to
the input and centered at PWIN pin determines
the input voltage UVLO point in charge mode of
the MP2636.
PWIN IN
RL
VV (V)
RH RL
=×
+
(3)
If the voltage at PWIN pin is higher than 0.8V,
and the input voltage is lower than 6.0V, the
MP2636 works in the charge mode. During
normal operation (V
UVLO
<V
IN
<6.0V), the MP2636
can be forced into Boost Mode by pulling PWIN
pin to GND.
To achieve wide operation suggest set the
minimum input voltage at 4.5V.
Boost Mode: Boost mode can be enabled via
the MODE pin as long as the input voltage is
higher than 6V or the voltage at PWIN is lower
than 0.8V.
Sleep Mode: when the input voltage is lower
than 2V, the MP2636 enters sleep mode
operation thus consuming very low current from
the battery.
Input Current Limiting in Charge Mode
The MP2636 has a dedicated pin that programs
the input-current limit. The average input current
of the MP2636 is determined by the resistor
value between ILIM and GND. As the total input
current approaches the programmed input
current limit, charge current is reduced to allow
priority to system power.
Use the following equation to determine the input
current limit threshold,
ILIM
ILIM
43.3(k )
I (A) 0.05
R(k)
Ω
=−
Ω
(4)
Input Voltage Regulation in Charge Mode
In charge mode, if the input power source is not
sufficient to support the charge current and
system load current, the input voltage will
decrease. As the input voltage approaches the
programmed input voltage regulation value, the
charge current is reduced to allow priority of the
system power and maintain proper regulation of
the input voltage.
The input voltage can be regulated by resistor
divider from IN pin to REG pin to AGND
according to the following equation:
REG IN_ R
R4
VV (V)
R3 R4
=×
+
(5)
where V
REG
is the internal voltage reference,
which is 1.2V, and the V
IN_R
is the desired
regulation voltage.