X3100 Xicor, X3100 Datasheet - Page 18

• Manufacturer Part Number: X3100
• Description: 3 or 4 Cell Li-Ion Battery Protection and Monitor IC
• Manufacturer: Xicor

X3100/X3101 – Preliminary Information
Over-Current Protection
In addition to monitoring the battery cell voltages, the
X3100 and X3101 continually monitor the voltage VCS
(VCS
(R
then the device enters over-current protection mode
(Figure 7). In this mode, the X3100 and X3101
automatically switch the discharge FET OFF (UVP/
OCP=Vcc) and hence prevent current from flowing
through the terminals P+ and P-.
Figure 7. Over-Current Protection
The 5VDC voltage regulator output (V
active during an over-current protection mode.
Once the device enters over-current protection mode,
the X3100 and X3101 begin a load monitor state. In the
load monitor state, a small current (I
passed out of pin OVP/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 7.)
REV 1.1.8 12/10/02
SENSE
2
–VCS
X3100/X3101
VSS
). If VCS
1
) across the current sense resistor
OVP/LMON
VCS1
R
SENSE
21
Q2
> V
FET Control
Circuitry
VCS2
OC
for a time exceeding T
Q10
D1
I
LMON
LMON
V
RGO
RGO
=7.5µA typ.) is
Load
) is always
P-
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P+
OC
21
,
If the load resistance > 150kΩ (I
exceeding T
from over-current protection mode. The discharge FET
is then automatically switched ON (UVP/OCP=Vss) by
the X3100 or X3101, unless the status of UVP/OCP has
been changed in control register (by manipulating bit
UVPC) during the over-current protection mode.
T
between pin OCT and VSS. A list of typical delay times
is shown in Table 23. Note that the value C
larger than 1nF.
The delay T
capacitance C
equations:
Table 23. Typical Over-Current Delay Times
The value of V
shown in 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 through an unused X3101 cell
balance output, or directly from a microcontroller port
instead of connecting to V
Symbol
OC
T
T
OCR
/T
OC
OCR
are varied using a capacitor (C
Over-current
detection delay
Over-current
release time
OCR
OC
T
T
OCR
Description
OC
OC
and T
OC
, then the X3100 or X3101 is released
(ms) ≈ 10,000 x C
can be approximated by the following
Characteristics subject to change without notice.
(ms) ≈ 10,000 x C
can be selected from the values
OCR
RGO
that results from a particular
.
0.001
0.001
LMON
C
OC
OC
OC
µ F
µ F
(µF)
=0µA) for a time
(µF)
OC
OC
10ms (Typ)
10ms (Typ)
) connected
should be
Delay
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