MCP73861-I/SL Microchip Technology Inc., MCP73861-I/SL Datasheet - Page 15

• Manufacturer Part Number: MCP73861-I/SL
• Description: Highly-Integrated Single Cell Lithium-Ion/Lithium-Polymer Charge Management Cont
• Manufacturer: Microchip Technology Inc.

Specifications of MCP73861-I/SL

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

5.0
5.1
5.1.1
The V
The MCP7386X automatically enters a Power-down
mode if the voltage on the V
UVLO voltage (V
the battery pack when the V
5.1.2
Fast charge current regulation can be scaled by placing
a programming resistor (R
to V
maximum fast charge current of 1.2A, typically. The
minimum fast charge current is 100 mA, set by letting
the PROG input float. The following formula calculates
the value for R
The preconditioning trickle-charge current and the
charge termination current are scaled to approximately
10% and 8% of I
5.1.3
A 2.5V voltage reference is provided to bias an external
thermistor for continuous cell temperature monitoring
and prequalification. A ratio metric window comparison
is performed at threshold levels of V
V
5.1.4
The MCP73861/2/3/4 continuously monitors tempera-
ture by comparing the voltage between the THERM
input and V
thresholds. A negative or positive temperature
coefficient, NTC or PTC thermistor and an external
voltage-divider typically develop this voltage. The
temperature sensing circuit has its own reference to
which it performs a ratio metric comparison. Therefore,
it is immune to fluctuations in the supply input (V
The temperature-sensing circuit is removed from the
system when V
discharge of the battery pack.
© 2005 Microchip Technology Inc.
where:
THREF
R
SS
PROG
I
REG
DD
. Connecting the PROG input to V
/4.
DETAILED DESCRIPTION
Analog Circuitry
input is the input supply to the MCP7386X.
= the desired fast charge current in amps.
= measured in k
BATTERY MANAGEMENT INPUT
SUPPLY (V
PROG INPUT
CELL TEMPERATURE SENSOR
BIAS (THREF)
CELL TEMPERATURE SENSOR
INPUT (THERM)
SS
R
PROG
DD
with the upper and lower temperature
PROG
REG
STOP
is not applied, eliminating additional
:
, respectively.
). This feature prevents draining
=
13.2 11 I
----------------------------------------
DD1
12 I
PROG
DD
, V
–
DD
REG
supply is not present.
) from the PROG input
DD2
input falls below the
–
)
REG
1.2
SS
THREF
allows for a
/2 and
DD
).
Figure 6-1 depicts a typical application circuit with
connection of the THERM input. The resistor values of
R
equations.
For NTC thermistors:
For PTC thermistors:
Applying a voltage equal to V
input disables temperature monitoring.
5.1.5
The TIMER input programs the period of the safety
timers by placing a timing capacitor (C
the TIMER input pin and V
programmed via the timing capacitor.
The preconditioning safety timer period:
The fast charge safety timer period:
The elapsed time termination period:
The preconditioning timer starts after qualification and
resets when the charge cycle transitions to the fast
charge, Constant-current mode. The fast charge timer
and the elapsed timer start once the MCP7386X
transitions from preconditioning. The fast charge timer
resets when the charge cycle transitions to the
Constant-voltage mode. The elapsed timer will expire
and terminate the charge if the sensed current does not
diminish below the termination threshold.
During thermal regulation, the timer is slowed down
proportional to the charge current.
Where:
T1
and R
R
resistance values at the temperature window
of interest.
COLD
t
PRECON
t
TIMER SET INPUT (TIMER)
t
TERM
FAST
MCP73861/2/3/4
T2
R
R
R
R
and
T1
T2
T1
T2
are calculated with the following
=
=
=
=
=
=
=
C
------------------ -
C
------------------ -
R
0.1 F
0.1 F
2 R
----------------------------------------------
2 R
----------------------------------------------
R
2 R
----------------------------------------------
2 R
----------------------------------------------
R
C
------------------ -
TIMER
TIMER
0.1 F
HOT
COLD
HOT
R
R
TIMER
COLD
HOT
COLD
COLD
COLD
COLD
SS
–
–
–
3 R
are
. Three safety timers are
1.5Hours
3 R
3.0Hours
–
THREF
R
1.0Hours
R
COLD
HOT
R
R
R
R
COLD
the
HOT
HOT
HOT
HOT
HOT
DS21893C-page 15
/3 to the THERM
TIMER
thermistor
) between