X3100V28T1 Intersil, X3100V28T1 Datasheet - Page 5

• Manufacturer Part Number: X3100V28T1
• Description: IC PROTECT/MONITOR 4CELL 28TSSOP
• Manufacturer: Intersil

Specifications of X3100V28T1

• Function: Battery Monitor
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 6 V ~ 24 V
• Operating Temperature: -20°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Power to the X3100 or X3101 is applied to pin VCC via
diodes D6 and D7. These diodes allow the device to be
powered by the Li-Ion battery cells in normal operating
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 22. 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 V
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 (T
stable, regulated output in the range of 5VDC ± 10% (see
Figure ). 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, V
reference voltage for the A/D converter in the
microcontroller. Repeated power-up operations, consistently
re-apply the same “tuned” value for V
Figure 1 shows a battery pack temperature sensor
implemented as a simple resistive voltage divider, utilizing a
thermistor (R
to the A/D input of a microcontroller and used to measure
and monitor the temperature of the battery cells. R
be chosen with consideration of the dynamic resistance
range of R
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 19), 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 R
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 (V
V
(V
used to ensure that the charge FET is completely turned
OFF when OVP/LMON = V
D7
P+
). Since the drain of Q2 is connected to a higher potential
) a pull-up resistor (R
T
PU
as well as the input voltage range of the
T
is connected across the gate and drain of the
) and resistor (R
RGO
to decay to 0.1V in 170ms or less
PU
CC
) in the order of 1MΩ should be
.
5
T
’). The voltage V
PUR
RGO
RGO
+ T
can be used as a
OC
.
), V
RGO
T
can be fed
T
’ should
has a
X3100, X3101
P+
-
The capacitors on the V
first order low pass filter configuration, at the battery cell
voltage monitoring inputs (VCELL1 - VCELL4) of the X3100
or X3101. This filter is used to block any unwanted
interference signals from being inadvertently injected into
the monitor inputs. These interference signals may result
from:
• Transients created at battery contacts when the battery
• Electrostatic discharge (ESD) from something/someone
• Unfiltered noise that exists in the host device.
• RF signals which are induced into the battery pack from
Such interference can cause the X3100 or X3101 to operate
in an unpredictable manner, or in extreme cases, damage
the device. As a guide, the capacitor should be in the order
of 0.01µF and the resistor, should be in the order of 10kΩ
The capacitors should be of the ceramic type. In order to
minimize interference, PCB tracks should be made as short
and as wide as possible to reduce their impedance. The
battery cells should also be placed as close to the X3100 or
X3101 monitor inputs as possible.
Resistors R
Q
and X3101 provide internal drive circuitry which allows the
user to switch FETs Q
microcontroller and SPI port (see section “Cell Voltage
Balance Control (CBC1-CBC4)” on page 12). When any of
the these FETs are switched ON, a current, limited by
resistor R
so, the user can control the voltage across each individual
battery cell. This is important when using Li-Ion battery cells
since imbalances in cell voltages can, in time, greatly reduce
the usable capacity of the battery pack. Cell voltage
balancing may be implemented in various ways, but is
usually performed towards the end of cell charging (“Top-of-
charge method”). Values for R
specific application.
The internal 4kbit EEPROM memory can be used to store
the cell characteristics for implementing such functions as
gas gauging, battery pack history, charge/discharge cycles,
and minimum/maximum conditions. Battery pack
manufacturing data as well as serial number information can
also be stored in the EEPROM array. An SPI serial bus
provides the communication link to the EEPROM.
A current sense resistor (R
monitor the current flowing into/out of the battery terminals,
and is used to protect the pack from over-current conditions
(see section “Over-Current Protection” on page 19). R
is also used to externally monitor current via a
9
pack is being connected/disconnected from the charger or
the host.
touching the battery contacts.
the surrounding environment.
) are used for battery cell voltage balancing. The X3100
CB
CB
, flows across the particular battery cell. In doing
and the associated n-channel MOSFET’s (Q
6
- Q
CELL1
9
SENSE
ON or OFF via the
to V
CB
will vary according to the
) is used to measure and
CELL4
inputs are used in a
January 3, 2008
SENSE
FN8110.1
6
.
-