Flow Chart Explanation, fosc = 800 Hz
(Figures 2, 3 and 4)
Battery pack insertion disables the voltage lock at battery
detection input Pin 10. All functions in the integrated
circuit are reset. For further description, DIP-pinning is
taken into consideration.
Battery Insertion and –dV Monitoring
The charging procedure will be carried out if battery
insertion is recognised. If the polarity of the inserted
battery is not according to the specification, the fast
charge rate will stop immediately. After the polarity test,
if positive, the defined fast charge rate, IO, begins for the
first 5 minutes according to –dV monitoring. After
5 minutes of charging, the first identification control is
If the inserted battery has a signal across its terminal of
less than 0.1 V, then the charging procedure is interrupted.
This means that the battery is defective i.e., it is not a
rechargeable battery – “shorted batteries ignored”.
Voltage and temperature measurements across the battery
are carried out during charge break interval (see figure 6),
i.e., currentless or idle measurements.
If the inserted battery is fully charged, the –dV control
will signal a charge stop after six measurements
(approximately 110 seconds). All the above mentioned
functions are recognised during the first 5 minutes
according to –dV method. During this time, +d2V/dt2
remains inactive. In this way the battery is protected from
If there is no charge stop within the first 5 minutes after
battery insertion, then d2V/dt2 monitoring will be active.
In this actual charge stage, all stop-charge criteria are
When close to the battery’s capacity limit, the battery
voltage curve will typically rise. As long as the +d2V/dt2
stop-charging criteria are met, the device will stop the fast
Top-Off Charge Stage
By charge disconnection through the + d2V/dt2 mode, the
device switches automatically to a defined protective
top-off charge with a pulse rate of 1/4 IO (pulse time,
tp = 5.12 s, period, T = 20.48 s).
The top-off charge time is specified for a time of
20 minutes @ 800 Hz.
Trickle Charge Stage
When top-off charge is terminated, the device switches
automatically to trickle charge with 1/256 IO (tp = 5.12 s,
period = 1310.72 s). The trickle continues until the
battery pack is removed.
Power Supply, Figure 2
The charge controller allows the direct power supply of
8 to 26 V at Pin 15. Internal regulation limits higher input
voltages. Series resistance, R1, regulates the supply
current, IS, to a maximum value of 25 mA. Series
resistance is recommended to suppress the noise signal,
even below 26 V limitation. It is calculated as follows:
Vmin– 8 V
Itot = IS + IRB1 + I1
Vmax, Vmin = Rectified voltage
IS = Current consumption (IC) without load
IRB1 = Current through resistance, RB1
I1 = Trigger current at Pin 1
Rev. A3, 14-Nov-96