QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 756
COULOMB COUNTER/BATTERY GAS GAUGE
5
QUICKEVAL
DC756 is a part of the QuickEval system, which al-
lows for quick evaluation of the LTC4150 with a soft-
ware interface. DC756 connects via 14-pin ribbon
cable to a DC590, USB controller board. The DC590
is connected to a PC through USB. The QuickEval
software reads DC756’s board ID and opens the soft-
ware interface shown in Figure 4.
1) Start Counter
The Start Counter check box starts and stops the
software timer. When the box is checked, the timer is
started and the time is recorded on the “Start Time”
label. A read out from the shift register is executed
approximately every 50ms. If there is a change in the
data from the last read, the interface will be updated
and the change is logged on the Data Change Log.
When an interrupt is read, a clear bit command is
sent.
Unchecking the Start Counter check box stops the
timer to halt any data readout and displays the stop
time.
2) Board Status
When the software timer is started, the board status
is updated. The display will show if either a battery or
charger is present. If one is present, the battery
charge or discharge is then indicated. When an inter-
rupt line is low, the Interrupt display is shown as
True. The clear bit sends a clear bit command to the
Clear pin of the LTC4150. A clear bit is sent out to
the LTC4150 if the timer is on and an interrupt is
read. Clicking Clear Bit manually sends a clear bit.
3) Coulomb Counter
The Coulomb Count display is updated every time an
interrupt occurs. When the battery is charging, the
interrupt count increments, while discharging decre-
ments the count. The Max Count shows the highest
count and the Min Count is the lowest. Total Up
Count counts up every time the battery is charging
and total Down Count counts down every time the
battery is discharging. Reset Count resets the count
display. These counts can also be displayed in Cou-
lombs and milliAmpere-hours (mAh). The unit con-
versions are as follows:
1 Count = 1 Interrupt
# of Coulombs = # of Interrupts / (Gvf • R
SENSE
)
# of mAh = # of Interrupts / (Gvf • R
SENSE
• 3600)
4) Battery Gas Gauge
The battery charge information is displayed here in
mAh. Charge remaining increases when a charge and
interrupt occurs and decreases from a discharge and
interrupt. The amount the charge increments and
decrements in the battery depends on the Charge and
Discharge Efficiencies entered in the Set Up section.
1 Chrg = (Charge Eff / 100) • 1 Int / (Gvf • R
SENSE
)
1 DsChrg = (100/DsChrg Eff) •1 Int/(Gvf • R
SENSE
)
The gas gauge display is the charge remaining di-
vided by the maximum charge for the battery. The
Max. Charge is entered in the Set Up section.
5) Battery Setup
Enter in the Charge Efficiency and Discharge Effi-
ciency. These efficiencies are calculated into the bat-
tery charge in the Battery Gas Gauge section. Enter
the Maximum Charge in mAh of the battery con-
nected to the DC756. Enter the value of R
SENSE
if
the resistor on the board is changed from the original
0.01Ω.
