x3102v28 Intersil Corporation, x3102v28 Datasheet - Page 23
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x3102v28
Manufacturer Part Number
x3102v28
Description
3 Cell Li-ion Battery Protection And Monitor Ic
Manufacturer
Intersil Corporation
Datasheet
1.X3102V28.pdf
(32 pages)
Overcurrent Protection
In addition to monitoring the battery cell voltages, the X3102
continually monitors the voltage VCS
across the current sense resistor (R
for a time exceeding T
protection mode (Figure 7). In this mode, the X3102
automatically switches the discharge FET OFF (UVP/OCP =
Vcc) and hence prevent current from flowing through the
terminals P+ and P-.
The 5VDC voltage regulator output (V
during an overcurrent protection mode.
Once the device enters overcurrent protection mode, the
X3102 begin a load monitor state. In the load monitor state, a
small current (I
LMON in order to determine the load resistance. The load
resistance is the impedance seen looking out of pin OVP/
LMON, between terminal P+ and pin VSS (See Figure 13.)
If the load resistance >
exceeding T
overcurrent protection mode. The discharge FET is then
automatically switched ON (UVP/OCP = Vss) by the X3102,
unless the status of UVP/OCP has been changed in control
register (by manipulating bit UVPC) during the overcurrent
protection mode.
T
between pin OCT and VSS. A list of typical delay times is
shown in Table 23. Note that the value C
than 1nF.
The delay T
capacitance C
equations:
T
OC
OC
/T
(ms) |10,000 x C
X3102
VSS
OCR
FIGURE 13. OVERCURRENT PROTECTION
are varied using a capacitor (C
OC
OCR
OC
LMON
OVP/LMON
and T
VCS1
, then the X3102 is released from
R
can be approximated by the following
SENSE
= 7.5µA typ.) is passed out of pin OVP/
OCR
OC
Q2
OC
FET Control
R
Circuitry
, then the device enters overcurrent
OCR
VCS2
that results from a particular
(µF)
23
(I
LMON
SENSE
Q10
D1
21
I
RGO
LMON
= 0µA) for a time
V
(VCS
OC
RGO
). If VCS
OC
) is always active
should be larger
2
) connected
–VCS
R
(Load)
OCR
21
1
)
> V
P-
P+
OC
X3102
T
The value of V
Table 6, by setting bits VOC1, VOC0 in the configuration
register using the WCFIG command.
Note: If the Charge FET is turned off, due to an overcharge
condition or by direct command from the microcontroller, the
cells are not in an undervoltage condition and the pack has a
load, then excessive current may flow through Q10 and
diode D1. To eliminate this effect, the gate of Q10 can be
turned off by the microcontroller.
OCR
Symbol
T
T
OCR
OC
TABLE 23. TYPICAL OVERCURRENT DELAY TIMES
(ms) |10,000 x C
Overcurrent
detection delay
Overcurrent
release time
OC
Description
can be selected from the values shown in
OC
(µF)
0.001
0.001
C
OC
µ
µ
F
F
December 22, 2004
10ms (Typ)
10ms (Typ)
Delay
FN8246.0