Datasheet
2009-2013 Microchip Technology Inc. DS20002183E-page 21
MCP73113/4
6.0 APPLICATIONS
The MCP73113/4 devices are designed to operate
with a host microcontroller or in stand-alone applica-
tions. The MCP73113/4 provides the preferred charge
algorithm for Lithium-Ion and Lithium-Polymer cells
Constant-current followed by Constant-voltage.
Figure 6-1 depicts a typical stand-alone application
circuit, while Figure 6-2 depicts the accompanying
charge profile.
FIGURE 6-1: Typical Application Circuit.
FIGURE 6-2: Typical Charge Profile
(875 mAh Battery).
6.1 Application Circuit Design
Due to the low efficiency of linear charging, the most
important factors are thermal design and cost, which
are a direct function of the input voltage, output current
and thermal impedance between the battery charger
and the ambient cooling air. The worst-case situation is
when the device has transitioned from the
Preconditioning mode to the Constant-Current mode.
In this situation, the battery charger has to dissipate the
maximum power. A trade-off must be made between
the charge current, cost and thermal requirements of
the charger.
6.1.1 COMPONENT SELECTION
Selection of the external components in Figure 6-1 is
crucial to the integrity and reliability of the charging
system. The following discussion is intended as a guide
for the component selection process.
6.1.1.1 Charge Current
The preferred fast charge current for Li-Ion/Li-Poly cells
is below the 1C rate, with an absolute maximum current
at the 2C rate. The recommended fast charge
current should be obtained from the battery
manufacturer. For example, a 500 mAh battery pack
with 0.7C preferred fast charge current has a charge
current of 350 mA. Charging at this rate provides the
shortest charge cycle times without degradation to the
battery pack performance or life.
+
–
STAT
V
DD
NC
PROG
V
BAT
1-Cell
5
6
7
1
2
AC-DC Adapter
NC
V
DD
V
SS
V
SS
8
9
10
4
3
R
LED
C
IN
C
OUT
V
BAT
R
PROG
Li-Ion
Battery
MCP73113/4 Typical Application
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0 153045607590105120
Supply Current (A)
Battery Voltage (V)
Time (Minutes)
R
PROG
= 2 K
875 mAh Battery
Note: Please consult with your battery supplier
or refer to the battery data sheet for
preferred charge rate.