ACT2802C datasheet(15/25 Pages) ACTIVE-SEMI

15 / 25 page

Rev 7, 15-Jul-16

Innovative PowerTM

- 15 -

www.active-semi.com

ACT2802/ACT2802B/ACT2802C

Battery Impedance Compensation

external resistor is used to set the impedance

from 40mΩ to 500mΩ as shown in Figure 15. 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 16.

Boost Output Plug-in Auto Detection

Figure 17 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 18 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

ACT2802/ACT2802B/ACT2802C

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 capacitor is recommended while on

output side, 3*22uF ceramic capacitors are

recommended.

Battery Temperature Monitoring

ACT2802 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

limits.

In a typical application, the TH pin is connected to

the battery pack's thermistor input as shown in

Figure 19. The ACT2802 injects a 60µA current out of

the TH pin into the thermistor, so that the thermistor

resistance is monitored by comparing the voltage at

TH to the internal VTHL and VTHH thresholds of 0.3V

and 1.5V, respectively. When VTH > VTHH or VTH < VTHL

charging and the charge timers are suspended. When

VTH returns to the normal range, charging and the

charge timers resume.

The threshold is given by:

)

RIMC







(7)

(6)

BAT

)

(

)

(

)

(

BAT

)

(









Figure 15.

Battery impedance compensation setting circuit

RIMC(KΩ)

100

200

Battery

Impedance

R(mΩ)

Rcs=25mΩ

100

200

Rcs=50mΩ

100

200

400

Figure 16. Input over voltage surge protection circuit

Figure 17.

Boost output auto detection circuit

Figure 18.

Input over voltage protection

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