ACT2801_16 datasheet(15/25 Pages) ACTIVE-SEMI

15 / 25 page

Rev 8, 01-Nov-16

Innovative PowerTM

- 15 -

www.active-semi.com

ACT2801/ACT2801B

The IOST pin voltage is proportional to output

current until output current is limited, as shown in

Figure 15.

Battery Impedance Compensation

external resistor is used to set the impedance

from 40mΩ to 500mΩ as shown in Figure 16. RIMC

is corresponding to battery impedance. Higher RIMC

gives higher compensation voltage which is

positively proportional to battery charge/discharge

current.

Select RIMC based on battery impedance:

The battery impedance as shown in the table 4

according to the RIMC and Rcs:

Table 4: Battery Impedance

Input Over Voltage Surge

In the case of pure ceramic input capacitor is

chosen, if the input cable is long, stray inductance

may cause over voltage spikes as twice as the

steady-state voltage when input source is plugged

in. Below input circuit is recommended to avoid

input voltage surge. R1 resistor is added in series

with capacitor C1 to damp the potential LC

resonance as shown in Figure 17.

Boost Output Plug-in Auto Detection

Figure 18 provides a solution for auto plug-in

detection.

External Input Over Voltage Protection

Considering the maximum voltage rating at VIN pin,

the external OVP circuit as shown in Figure 19 is

recommended if input voltage may go higher than

7V. With the enhanced OVP circuit, the design can

pass UN38.3.

Inductor and Capacitor Selection

ACT2801/ACT2801B supports SMD components.

2.2uH inductor is recommended. Input side, 4.7uF

ceramic capacitor in series with 2.7Ω resistor are

recommended, on battery side, 22uF ceramic

capacitors is recommended while on output side,

2*22uF ceramic capacitors are recommended.

Battery Temperature Monitoring

ACT2801 continuously monitors the temperature of

the battery pack by sensing the resistance of its

thermistor,

and

suspends

charging

the

temperature of the battery pack exceeds the safety

900

750

450

300

150

600

Output current(A)

0.2

0.4

0.6

0.8

1.0

1.2

Figure 15.

VIOST VS. output current

VBAT = 3.7V

RIOST=97.6kΩ

)

RIMC







(7)

(6)

Figure 16.

Battery impedance compensation setting circuit

BAT

)

(

)

(

)

(

BAT

)

(









RIMC(KΩ)

100

200

Battery

Impedance

R(mΩ)

Rcs=25mΩ

100

200

Rcs=50mΩ

100

200

400

Figure 17. Input over voltage surge protection circuit

Figure 18.

Boost output auto detection circuit

Figure 19.

Input over voltage protection

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