ACT2823
REV 1, 01-DEC-2016
Discharge Mode
Conventional – Always On Mode
In Discharge Mode, the ACT2823 turns off Q1 and
reconfigures Q2 and Q3 as a buck converter. It powers
the VOUT pin from the battery. The default VOUT
voltage is 5.07V and current limit is set at 3.3A. If a
charged battery is present when input power is removed,
the IC enters Discharge Mode. There is a 2s transition
between Charge Mode and Discharge Mode. During
this time, the IC goes into HZ mode.
Setting RPT=4kΩ programs Conventional – Always On
Mode. The LEDs are always active when the IC is in
Charge or Discharge Mode. The LEDs are solid to
indicate Charge Mode and flash to indicate Discharge
Mode. Figure 4 shows each LED function relative to the
VBAT voltage.
Conventional Mode
HZ Mode
Setting RPT=12kΩ programs Conventional Mode. The
LEDs are always active when the IC is in Charge Mode.
They only turn on for 5s when PB is pulled low for
greater than 40ms in Discharge Mode. The LED pattern
is identical to Conventional – Always On Mode. Figure
4 shows each LED function relative to the VBAT voltage.
HZ mode is a low power mode that minimizes current
draw from the battery. All switches are turned off, and
only the push button circuit is kept alive. The IC draws
less than 10uA current from VBAT in HZ Mode. The IC
transitions from Discharge Mode to HZ Mode when the
load current is less than 10mA for greater than 12.5s or
when the pushbutton is pressed for greater than 5s. The
IC also enters HZ Mode when a battery fault is detected.
The IC stays in HZ Mode indefinitely until input voltage
is applied. When input voltage is applied and there are
no faults, it enters Charge Mode. The user can force a
transition from HZ Mode to Discharge Mode by
asserting the push button for greater than 40ms.
Breathing Mode
Setting RPT=24kΩ programs Breathing Mode. The LEDs
are always active when the IC is in Charge Mode. They
only turn on for 5s when PB is pulled low for greater than
40ms in Discharge Mode.In Charge Mode, the LEDs
appear to “breath” as the IC ramps the current back and
forth between 0mA and 3mA at a 2s rate. In Discharge
mode, the LED pattern is identical to Conventional
Mode. Figure 4 shows each LED function relative to the
VBAT voltage.
Push Button
The ACT2823 push button serves several purposes. It
can be automatically pulled low when a shielded cable
or a portable device is connected to VOUT. When in HZ
Mode, and PB is pulled low for greater than 40ms, it
turns on the LEDs for 5s and the IC transitions to
Discharge Mode. This allows the user to wake up the IC
to power a portable device. The PB falling threshold is
0.95V when in HZ Mode.
Bottom Charging Mode
Setting RPT=40kΩ programs Bottom Charging Mode.
The LEDs are always active when the IC is in Charge
Mode. They only turn on for 5s when PB is pulled low
for greater than 40ms in Discharge Mode. In Charge
Mode, the LED cycle starts with all LEDs off. LED1 turns
on, then LED2 turns on, etc. until the highest LED
corresponding to the battery voltage turns on. Then all
LEDs turn off. This cycle repeats every 0.5s. In
Discharge mode, the LED pattern is identical to
Conventional Mode. Figure 4 shows each LED function
relative to the VBAT voltage.
When in Charge Mode, pulling PB below 3.5V tells the
IC that a shielded USB cable or a downstream portable
device is connected to VOUT. This changes the Charge
Current Foldback Voltage threshold from 4.7V to 4.92V.
Increasing this threshold gives more current priority to
the portable device connected to VOUT. If the portable
device is removed and PB rises above 3.5V, the Current
Foldback Threshold drops back to 4.7V.
Circulating Mode
Figure
8
shows the recommended circuit for
automatically detecting the shielded cable or portable
device connection. R26, R14 and C16 form the
detection circuit. Connect R14 and C16 to the USB
output connector shield to detect the insertion of a
shielded cable. Connect to the USB cable’s output
voltage to detect insertion of a portable device.
Setting RPT greater than 56kΩ programs Circulating
Mode. RPT can be left open to program Circulating
Mode.The LEDs are always active when the IC is in
Charge Mode. They only turn on for 5s when PB is
pulled low for greater than 40ms in Discharge Mode. In
Charge Mode, when the battery voltage is over an
LED’s threshold, that LED stays on. The higher
threshold LEDs turn on one at a time until they are all
on. They then turn off. The cycle repeats every 0.5s. In
Discharge mode, the LED pattern is identical to
Conventional Mode. Figure 4 shows each LED function
relative to the VBAT voltage.
LED Indication
ACT2823 has 4 LED inputs to visually communicate the
battery status. Aresistor from PT to AGND programs the
LED mode. In all modes, when the battery is
discharging, LED1 flashes to indicate a low battery
when the battery voltage is lower than the VLED1
threshold. In all modes, all LEDs turn on solid when the
battery charger is in the End-of-Charge Mode.
LED1-4 Refresh Cycle
Every time VIN is applied or PB is pulled low, the LEDs
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ActiveSwitcherTM is a trademark of Active-Semi.
14
ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
