LC709203F
www.onsemi.com
13
Table 8. BATTERY PROFILE VS. REGISTER
IC Type
Battery
Type
Nominal/Rated
Voltage
Charging
Voltage
Design
Capacity
Number of
the Parameter
(0x1A)
Change of
the Parameter
(0x12)
LC709203Fxx−01xx 03 3.8 V 4.35 V ≥ 500 mAh 0x0301 0x0000
01 3.7 V 4.2 V −0x0001
LC709203Fxx−03xx 06 3.8 V 4.35 V < 500 mAh 0x0601 0x0000
01 3.7 V 4.2 V −0x0001
LC709203Fxx−04xx 05 ICR18650−26H (SAMSUNG) 0x0504 0x0000
04 UR18650ZY (Panasonic) 0x0001
LC709203Fxx−05xx 07 3.85 V 4.4 V −0x0706 0x0000
06 3.8 V 4.35 V < 500 mAh 0x0001
HG−CVR
Hybrid Gauging by Current-Voltage Tracking with
Internal Resistance
HG−CVR is ON Semiconductor’s unique method which
is used to calculate accurate RSOC. HG−CVR first
measures battery voltage and temperature. Precise reference
voltage is essential for accurate voltage measurement.
LC709203F has accurate internal reference voltage circuit
with little temperature dependency.
It also uses the measured battery voltage and internal
impedance and Open Circuit Voltage (OCV) of a battery for
the current measurement. OCV is battery voltage without
load current. The measured battery voltage is separated into
OCV and varied voltage by load current. The varied voltage
is the product of load current and internal impedance. Then
the current is determined by the following formulas.
V(VARIED) +V(MEASURED) *OCV (eq. 1)
I+
V(VARIED)
R(INTERNAL) (eq. 2)
Where V(VARIED) is varied voltage by load current,
V(MEASURED) is measured voltage, R(INTERNAL) is
internal impedance of a battery. Detailed information about
the internal impedance and OCV is installed in the LSI. The
internal impedance is affected by remaining capacity,
load-current, temperature, and more. Then the LSI has the
information as look up table. HG−CVR accumulates battery
coulomb using the information of the current and a steady
period by a high accuracy internal timer. The remaining
capacity of a battery is calculated with the accumulated
coulomb.
How to Identify Aging
By repeating discharge/charge, internal impedance of
a battery will gradually increase, and the Full Charge
Capacity (FCC) will decrease. In coulomb counting method
RSOC is generally calculated using the FCC and the
Remaining Capacity (RM).
RSOC +RM
FCC
100% (eq. 3)
Then the decreased FCC must be preliminarily measured
with learning cycle. But HG−CVR can measure the RSOC
of deteriorated battery without learning cycle. The internal
battery impedance that HG−CVR uses to calculate the
current correlates highly with FCC. The correlation is based
on battery chemistry. The RSOC that this LSI reports using
the correlation is not affected by aging.
Figures 24−26 show RSOC measurement result of
a battery with decreased FCC due to its aging. The shown
RSOC is based on the decreased FCC even with a battery
with 80% FCC after executing 300 times of discharge/
charge.
Automatic Convergence of the Error
A problem of coulomb counting method is the fact that the
error is accumulated over time − This error must be
corrected. The general gauges using coulomb counting
method must find an opportunity to correct it.
This LSI with HG−CVR has the feature that the error of
RSOC converges autonomously, and doesn’t require
calibration opportunities. The error constantly converges in
the value estimated from the Open Circuit Voltage.
Figure 27 shows the convergent characteristic example
from the initialize error.
Also, coulomb counting method cannot detect accurate
residual change because the amount of the current from
self-discharge is too small but HG−CVR is capable to deal
with such detection by using the voltage information.
Simple and Quick Setup
In general, it is necessary to obtain multiple parameters for
a fuel gauge and it takes a lot of resource and additional
development time of the users. One of the unique features of
LC709203F is very small number of parameters to be
prepared by the beginning of battery measurement – the
minimum amount of parameter which users may make is
one because Adjustment pack application register has to