x3102v28 Intersil Corporation, x3102v28 Datasheet - Page 19

• Manufacturer Part Number: x3102v28
• Description: 3 Cell Li-ion Battery Protection And Monitor Ic
• Manufacturer: Intersil Corporation

X3102 Internal Protection Functions
The X3102 provides periodic monitoring (See section
“Periodic Protection Monitoring” on page 19) for over-charge
and over-discharge states and continuous monitoring for an
overcurrent state. It has automatic shutdown when a
protection mode is encountered, as well as automatic return
after the device is released from a protection mode. When
sampling voltages through the analog port (Monitor Mode),
over-charge and over-discharge protection monitoring is
also performed on a continuous basis.
Voltage thresholds for each of these protection modes (V
V
software and stored in an internal non-volatile register. This
feature allows the user to avoid the restrictions of mask
programmed voltage thresholds, and is especially useful
during prototype/evaluation design stages or when cells with
slightly different characteristics are used in an existing
design.
Delay times for the detection of, and release from protection
modes (T
individually varied by setting the values of external capacitors
connected to pins OVT, UVT, OCT.
Periodic Protection Monitoring
In normal operation, the analog select pins are set such that
AS2 = L, AS1 = L, AS0 = L. In this mode the X3102
conserves power by sampling the cells for over or over-
discharge conditions.
In this state over-charge and over-discharge protection
circuitry are usually off, but are periodically switched on by
the internal Protection Sample Rate Timer (PSRT). The over-
charge and over-discharge protection circuitry is on for
approximately 2ms in each 125ms period. Overcurrent
monitoring is continuous. In monitor mode (See page 25)
over-charge and over-discharge monitoring is also
continuous.
UV
OVP/LMON
, and V
Event
OV
V
CELL
OC
, T
UV
respectively) can be individually selected via
0
/T
UVR
Normal Operation Mode
, and T
19
OC
/T
FIGURE 11. OVER-CHARGE PROTECTION MODE-EVENT DIAGRAM
OCR
respectively) can be
1
T
OV
OV
2
,
X3102
Protection Mode
Over-charge
Over-charge Protection
The X3102 monitors the voltage on each battery cell
(V
T
(OVP/LMON=V
charge protection mode (Figure 11). The status of the
discharge FET (via pin UVP) will remain unaffected.
While in over-charge protection mode, it is possible to
change the state of the OVPC bit in the control register such
that OVP/LMON=Vss (Charge FET=ON). Although the
OVPC bit in the control register can be changed, the change
will not be seen at pin OVP until the X3102 returns from
over-charge protection mode.
The over-charge detection delay T
capacitor (C
typical delay time is shown in Table 10. The delay T
results from a particular capacitance C
approximated by the following linear equation:
T
The device further continues to monitor the battery cell
voltages, and is released from over-charge protection mode
when V
released from over-charge protection mode, the charge FET
is automatically switched ON (OVP/LMON=V
device returns from over-charge protection mode, the status
of the discharge FET (pin UVP/OCP) remains unaffected.
The value of V
Table 4 by setting bits VOV1, VOV0. These bits are set by
using the WCFIG instruction to write to the configuration
register.
OV
OV
Symbol
CELL
T
TABLE 19. TYPICAL OVER-CHARGE DETECTION TIME
, then the Charge FET will be switched OFF
OV
(s) |10 x C
). If for any cell, V
CELL
OV
< V
OV
) connected between pin OVT and GND. A
CC
OVR
OV
can be selected from the values shown in
). The device has now entered Over-
(µF).
, for all cells. When the X3102 is
3
0.1µF
C
CELL
OV
Normal Operation Mode
> V
OV
OV
, is varied using a
for a time exceeding
OV
, can be
SS
1.0s (Typ)
December 22, 2004
Delay
). When the
V
V
OV
OVR
V
V
CC
SS
OV
FN8246.0
that