EGS5 Hardware Interface Description
3.5 Charging Control
75
EGS5_HD_v02.004
Page 45 of 123
2012-02-09
Confidential / Released
3.5.5
Implemented Charging Technique
If all requirements listed above are met (appropriate external charging circuit of application, bat-
tery pack, charger, AT^SBC settings) then charging is enabled in various stages depending on
the battery condition:
Trickle charging:
•
Trickle charge current flows over the VCHARGE line.
•
Temperature conditions: 0°C to 45°C. Outside this range no trickle charging is possible.
•
Trickle charging is done when a charger is present (connected to VCHARGE) and the bat-
tery is deeply discharged or has undervoltage.
- If deeply discharged (Deep Discharge Lockout at V
BATT+
= 0…2.5V) the battery is charged
with 30mA.
- In case of undervoltage (Undervoltage Lockout at V
BATT+
= 2.5…3.0V) the battery is
charged at 60mA.
- If V
BATT+
= 3.0V... 3.2V the battery is charged at 100mA.
Software controlled charging:
•
Controlled over the CHARGEGATE.
•
Temperature conditions: 0°C to 45°C. Outside this range no software controlled charging is
possible.
•
Software controlled charging is done when the charger is present (connected to
VCHARGE) and the battery voltage is at least above the undervoltage threshold. Software
controlled charging passes the following stages:
- Power ramp: Depending on the discharge level of the battery (i.e. the measured battery
voltage V
BATT+
) the software adjusts the maximum charge current for charging the battery.
The duration of power ramp charging is very short (less than 30 seconds).
- Fast charging: Battery is charged with constant current (approx. 500 mA) until the battery
voltage reaches 4.2 V (approx. 80% of the battery capacity).
- Top-up charging: The battery is charged with constant voltage of 4.2 V at stepwise reduc-
ing charge current until full battery capacity is reached.
Duration of charging:
•
EGS5 provides a software controlled timer set to 4 hours as a safety feature to prevent per-
manent charging of defective batteries. The duration of software controlled charging
depends on the battery capacity and the level of discharge. Normally, charging stops when
the battery is fully charged or, at the latest, when the software timer expires after 4 hours.
If the software timer expires a charging error occurs, i.e., the AT^SBC’s battery connecting
status (<bcs>) is 4. To prevent this time out the charge current should be adjusted to the
battery capacity.
