ACT2813/ACT2813C
Rev 2, 19-May-15
Select RIMC based on battery impedance:
Boost Output Constant Current
25 × R (mΩ )
Rcs (m Ω )
(4)
(5)
R
IMC(kΩ ) =
Boost output current is set by a resistor connected
from IOST pin to AGND as shown in Figure 8. The
boost output current is estimated as the following
equation:
VBAT(V ) = BAT(V )−IBAT(A)×R(mΩ )×10-3
2
RIOST (kΩ )
Rcs (mΩ )
IIOST (A) = ( A)×
(3)
3
Figure 11. Battery impedance compensation setting circuit
The battery impedance as shown in the table 4
according to the RIMC and Rcs:
Figure 8. Boost output current setting circuit
Table 4: Battery Impedance
Figure 9 gives out boost output current with various
RIOST
RIMC(KΩ)
50
50
100
100
200
200
200
400
.
Battery
Impedance
R(mΩ)
Rcs=25mΩ
Rcs=50mΩ
3.0
2.5
VBAT = 3.7V
CVout=4.5V
100
2.0
1.5
1.0
0.5
0
Boost Output Plug-in Auto Detection
Figure 12 provides a solution for auto plug-in
detection.
0
20
40
60
80
100
120
RIOST (kΩ)
Figure 9. Boost output current setting
The IOST pin voltage is proportional to output
current until output current is limited, as shown in
Figure 10.
900
VBAT = 3.7V
RIOST=100kΩ
750
600
450
300
150
0
Figure 12. Boost output auto detection circuit
External Input Over Voltage Protection
Considering the maximum voltage rating at VIN pin,
the external OVP circuit as shown in Figure 13 is
recommended if input voltage may go higher than
7V. With the enhanced OVP circuit, the design can
pass UN38.3.
0
0.4
0.8
Output Current(A)
Figure 10. VIOST VS. output current
1.2
1.6
2.0
2.4
2.8
Battery Impedance Compensation
An external resistor is used to set the impedance
from 40mΩ to 500mΩ as shown in Figure 11. RIMC
is corresponding to battery impedance. Higher RIMC
gives higher compensation voltage which is
positively proportional to battery charge/discharge
current.
Figure 13. Input over voltage protection
Innovative PowerTM
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