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X3100 Datasheet, PDF (19/40 Pages) Xicor Inc. – 3 or 4 Cell Li-Ion Battery Protection and Monitor IC | |||
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X3100/X3101 â Preliminary Information
Figure 8. Over-Current Protection ModeâEvent Diagram
Normal Operation Mode
Over-Current Protection Mode
B+
P+
P+ = (RLOAD+RSENSE) x ILMON
Normal Operation Mode
VOC
VCS2
TOC
UVP/OCP
TOCR
Voc
VSS
VCC
VSS
Event
0
1
2
3
4
Table 24. Over-Current Protection ModeâEvent Diagram Description
Event
[0,1)
[1]
(1,2)
[2]
(2,3)
Event Description
â Discharge FET is ON (OCP=Vss). Battery cells are permitted to discharge.
â VCS21 (VCS2âVCS1) is less than the over-current threshold voltage (VOC).
â The device is in normal operation mode (i.e. not in a protection mode).
â Excessive current flows through the battery terminals P+, dropping the voltage. (See Figure 8.).
â The positive battery terminal voltage (P+) falls, and VCS21 exceeds VOC.
â The internal over-current detection delay timer begins counting down.
â The device is still in Normal Operation Mode
The internal Over-current detection delay timer continues counting for TOC seconds.
â The internal over-current detection delay timer times out, AND VCS21 is still above VOC.
â The internal over-current sense circuitry switches the discharge FET OFF (UVP/OCP=Vcc).
â The device now begins a load monitor state by passing a small test current (ILMON=7.5µA) out of pin
OVP/LMON. This senses if an over-current condition (i.e. if the load resistance < 150kâ¦) still exists
across P+/P-.
â The device has now entered over-current protection mode.
â It is possible to change the status of UVPC and OVPC in the control register, although the status of pins
UVP/OCP and OVP/LMON will not change until the device has returned from over-current protection
mode.
â The X3100/X3101 now continuously monitors the load resistance to detect whether or not an over-
current condition is still present across the battery terminals P+/P-.
REV 1.1.8 12/10/02
www.xicor.com
Characteristics subject to change without notice. 19 of 40
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