ACT2801/ACT2801C
Rev 2, 15-Apr-14
FUNCTIONAL DESCRIPTION
ACT2801/ACT2801C is
a
complete battery
from battery is very low. ACT2801 system operation
flow chart as shown in Figure 1, and ACT2801C
system operation flow chart as shown in Figure 2.
charging and discharging power management
solution for applications of single-cell lithium-based
backup battery pack or power bank. There is a
power path from input to output with programmable
input current limit. When output is over loaded, the
input switch Q1 starts going into linear mode and
thus output voltage starts to drop. If output voltage
drops below 4.25V, the input switch Q1 turns off
and restart in 2 seconds.
Any transitions between boost mode and charge
mode go through HZ mode by turning off all the
switches Q1-Q3 into HZ mode for 2 seconds before
enabling the other mode.
The modes are determined by HZ pin and VIN pin
as shown in the table 1. A valid VIN voltage forces
ACT2801/ACT2801C into charge mode. Boost
mode is enabled if HZ pin is pulled low and VIN is
invalid or not present. When HZ=0, if PB is pulled
low for more than 100ms, boost converter is
enabled.
With the advanced ACT2801/ACT2801C
architecture, a synchronous buck/boost converter is
connected from VOUT to switching node (SW). With
the bidirectional architecture, the converter could be
configured as either buck to charge battery or boost
to discharge battery. With switching charger and
discharger, the higher charge current and higher
conversion efficiency are achieved.
Table 1: Mode Selection
HZ PIN
VIN Valid
Mode
0
0
0
1
1
0
1
1
Modes of Operation
Boost
Charge
HZ
Charge
ACT2801/ACT2801C has
3 operation modes:
charge mode, boost mode and high-impedance
(HZ) mode. In charge mode, the input current limit
Q1 is enabled and Q2 and Q3 operate as a buck
converter to charge battery. In boost mode, Q2 and
Q3 operate as boost converter to step battery
voltage up to +5V at VOUT, and the current limit
switch Q1 is turned off, and the reverse current from
VOUT to VIN is blocked. In HZ mode, all the
switches are turned off and the drainage current
Flashlight
ACT2801C has an Flashlight function. Once PB is
pressed for more than 3 seconds, the Flashlight is
switched on. The driver will deliver up to 50mA
current to the flashlight. If another 3 seconds event
happen, the flashlight will be switched off.
Figure 1:
ACT2801 System Operation Flow Chart
Innovative PowerTM
- 9 -
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ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
