X3101 datasheet(13/40 Pages) XICOR

13 / 40 page

X3100/X3101 – Preliminary Information

Characteristics subject to change without notice.

13 of 40

REV 1.1.8 12/10/02

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over-charge and over-discharge protection circuitry is on

for approximately 2ms in each 125ms period. Over-

current monitoring is continuous. In monitor mode (see

page 20) over-charge and over-discharge monitoring is

also continuous.

Over-charge Protection

The X3100 and X3101 monitor the voltage on each

battery cell (VCELL). If for any cell, VCELL > VOV for a

time exceeding TOV, then the Charge FET will be

switched OFF (OVP/LMON=VCC). The device has now

entered Over-charge protection mode (Figure 5). 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

X3100

X3101

returns

from

over-charge

protection mode.

The over-charge detection delay TOV, is varied using a

capacitor (COV) connected between pin OVT and GND.

A typical delay time is shown in Table 10. The delay TOV

that results from a particular capacitance COV, can be

approximated by the following linear equation:

TOV (s) ≈ 10 x COV (µF).

Table 19. Typical over-charge detection time

The device further continues to monitor the battery cell

voltages, and is released from over-charge protection

mode when VCELL< VOVR, for all cells. When the X3100

or X3101 is released from over-charge protection

mode, the charge FET is automatically switched ON

(OVP/LMON=VSS). When the device returns from over-

charge protection mode, the status of the discharge

FET (pin UVP/OCP) remains unaffected.

The value of VOV can be selected from the values

shown in Table 4 by setting bits VOV1, VOV0. These bits

are set by using the WCFIG instruction to write to the

conﬁguration register.

Figure 5. Over-charge Protection Mode—Event Diagram

Symbol

COV

Delay

TOV

0.1µF

1.0s (Typ)

VCELL

OVP/LMON

Normal Operation Mode

Over-charge

VOV

VOVR

TOV

Protection

Mode

Normal Operation Mode

VCC

VSS

Event

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