X3101 datasheet(4/40 Pages) XICOR

4 / 40 page

X3100/X3101 – Preliminary Information

Characteristics subject to change without notice.

4 of 40

REV 1.1.8 12/10/02

www.xicor.com

—Load Monitor (LMON)

In Over-current Protection mode, a small test current

(7.5µA typ.) is passed out of this pin to sense the load

resistance. The measured load resistance determines

whether or not the X3100 or X3101 returns from an

over-current protection mode (see section “Over-Current

Protection” on page 18).

Over-discharge (Under Voltage) Protection/

Over-current Protection (UVP/OCP):

Pin UVP/OCP controls the battery cell discharge via an

external power FET. This P-channel FET allows cell

discharge when UVP/OCP=Vss, and prevents cell

discharge when UVP/OCP=Vcc. The X3100 and X3101

turn the external power FET off when the X3100 or

X3101 detects either:

—Over-discharge Protection (UVP)

In this case, pin 24 is referred to as “Over-discharge

(Under-Voltage) protection (UVP)” (see section “Over-

discharge Protection” on page 15). UVP/OCP turns off

the FET to prevent damage to the battery cells by being

discharged to excessively low voltages.

—Over-current protection (OCP)

In this case, pin 24 is referred to as “Over-current

protection (OCP)” (see section “Over-Current Protection”

on page 18). UVP/OCP turns off the FET to prevent

damage to the battery pack caused by excessive current

drain (e.g. as in the case of a surge current resulting

from a stalled disk drive).

TYPICAL APPLICATION CIRCUIT

The X3100 and X3101 have been designed to operate

correctly when used as connected in the Typical

Application Circuit (see Figure 1 on page 5).

The power MOSFET’s Q1 and Q2 are referred to as the

“Discharge FET” and “Charge FET,” respectively. Since

these FETs are p-channel devices, they will be ON when

the gates are at VSS, and OFF when the gates are at

VCC. As their names imply, the discharge FET is used to

control cell discharge, while the charge FET is used to

control cell charge. Diode D1 allows the battery cells to

receive charge even if the Discharge FET is OFF, while

diode D2 allows the cells to discharge even if the charge

FET is OFF. D1 and D2 are integral to the Power FETs. It

should be noted that the cells can neither charge nor

discharge if both the charge FET and discharge FET are

OFF.

Power to the X3100 or X3101 is applied to pin VCC via

diodes D6 and D7. These diodes allow the device to be

conditions, and allow the device to be powered by an

external source (such as a charger) via pin P+ when the

battery cells are being charged. These diodes should

have sufﬁcient current and voltage ratings to handle both

cases of battery cell charge and discharge.

The operation of the voltage regulator is described in

section “Voltage Regulator” on page 21. This regulator

provides a 5VDC±0.5% output. The capacitor (C1)

connected from RGO to ground provides some noise

ﬁltering on the RGO output. The recommended value is

0.1µF or less. The value chosen must allow VRGO to

decay to 0.1V in 170ms or less when the X3100 or

X3101 enter the sleep mode. If the decay is slower than

this, a resistor (R1) can be placed in parallel with the

capacitor.

During an initial turn-on period (TPUR + TOC), VRGO has

a stable, regulated output in the range of 5VDC ± 10%

(see Figure 2). The selection of the microcontroller

should take this into consideration. At the end of this turn

on period, the X3100 and X3101 “self-tunes” the output

of the voltage regulator to 5V+/-0.5%. As such, VRGO

can be used as a reference voltage for the A/D converter

in the microcontroller. Repeated power up operations,

consistently re-apply the same “tuned” value for VRGO.

Figure 1 shows a battery pack temperature sensor

implemented as a simple resistive voltage divider,

utilizing a thermistor (RT) and resistor (RT’). The voltage

VT can be fed to the A/D input of a microcontroller and

used to measure and monitor the temperature of the

battery cells. RT’ should be chosen with consideration of

the dynamic resistance range of RT as well as the input

voltage range of the microcontroller A/D input. An output

of the microcontroller can be used to turn on the

thermistor divider to allow periodic turn-on of the sensor.

This reduces power consumption since the resistor

string is not always drawing current.

Diode D3 is included to facilitate load monitoring in an

Over-current protection mode (see section “Over-

Current Protection” on page 18), while preventing the

ﬂow of current into pin OVP/LMON during normal

operation. The N-Channel transistor turns off this

function during the sleep mode.

Resistor RPU is connected across the gate and drain of

the charge FET (Q2). The discharge FET Q1 is turned

off by the X3100 or X3101, and hence the voltage at pin

OVP/LMON will be (at maximum) equal to the voltage of

the battery terminal, minus one forward biased diode

voltage drop (VP+–VD7). Since the drain of Q2 is

connected to a higher potential (VP+) a pull-up resistor

X3101 Datasheet(PDF) 4 Page - Xicor Inc.

X3101 Datasheet(HTML) 4 Page - Xicor Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Datasheet Download

Link URL