X3100-01 Datasheet, PDF (6/41 Pages) Intersil Corporation – Cell Balancing Control

X3100, X3101
microcontroller (see section “Current Monitor Function” on
page 21).
FETs Q4 and Q5 may be required on general purpose I/Os
of the microcontroller that connect outside of the package. In
some cases, without FETs, pull-up resistors external to the
pack force a voltage on the V_CC pin of the microcontroller
during a pack sleep condition. This voltage can affect the
proper tuned voltage of the X3100/X3101 regulator. These
FETs should be turned-on by the microcontroller. (See
Figure 1.)
Power-on Sequence
Initial connection of the Li-Ion cells in the battery pack will
not normally power-up the battery pack. Instead, the X3100
or X3101 enters and remains in the SLEEP mode. To exit
the SLEEP mode, after the initial power-up sequence, or
following any other SLEEP MODE, a minimum of 16V
(X3100 V_SLR) or 12V (X3101 V_SLR) is applied to the VCC
pin, as would be the case during a battery charge condition.
(See Figure .)
When V_SLR is applied to VCC, the analog select pins (AS2 -
AS0) and the SPI communication pins (CS, CLK, SI, SO)
must be low, so the X3100 and X3101 power-up correctly
into the normal operating mode. This can be done by using a
power-on reset circuit.
When entering the normal operating mode, either from initial
power-up or following the SLEEP MODE, all bits in the
control register are zero. With UVPC and OVPC bits at zero,
the charge and discharge FETs are off. The microcontroller
must turn these on to activate the pack. The microcontroller
would typically check the voltage and current levels prior to
turning on the FETs via the SPI port. The software should
prevent turning on the FETs throughout an initial
measurement/calibration period. The duration of this period
is T_OV + 200ms or T_UV + 200ms, whichever is longer.
6
FN8110.1
January 3, 2008