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SS4003

2/01/2005 Rev.1.01

Charging Indicator

The SS4003 provides an output pin to indicate the battery charge status. The CLED output shows the

battery pack is in charge mode. When the external electric power is plugs in, the CLED is on (low) and

SS4003 starts to charge. The CLED turns off (high) when charge full condition is reached or external

power is removed. In case of charge fault condition, the CLED will alter the output state (high/low) in

every second. The CFLED will turn on (low) when the battery is in charge full state during charging

period. CFLED will turn off (high) in all other conditions.

Battery Remaining-Capacity Indication

The battery remaining-capacity is indicated by 5 LED output pins, LED1, LED2, LED3, LED4 and LED5.

Low voltages on output pins drive LEDs ON. To reflect the remaining capacity the LED outputs are ON

inclusively from LED1 to LED5. The more LED outputs ON the higher the capacity. When all 5 LEDs are

ON, the battery capacity reaches above 90% of the Full Charged Capacity. One, two, three and four

LEDs are ON when the capacity is above 10%, 25%, 50% and 75% of the Full Charged Capacity,

respectively. If the relative state of charge was lower than 10%, the LED1 flashes every second. In the

charge or discharge state, the LEDs keep showing the battery capacity. For saving the battery energy,

the LEDs are turned off after about 5 seconds if not in the charge or discharge state. If a negative going

signal is applied to DispSel pin and the pack is neither in charge mode nor in discharge mode, the

relative state of charge display function will activate. The display function will terminate after 5 seconds

if no state change occurred during the period of time.

Reset

The SS4003 is at reset state either first connected to the battery pack or the supply voltage goes below

VLV

R. On hard reset, the SS4003 initializes and reads the configuration data to configure the battery

pack. A suggested Reset circuits is illustrated in Application Circuits 1.

Sleep mode

The SS4003 switches into the sleep mode either no charge flow detected for more than 30 seconds or

the relative state of charge is 0%. In the sleep mode, most of logic circuitry in the chip is turned off to

minimize the power consumption. SS4003 resumes operation either an external power is plugged in or

detects current flow through the sense resistor or display function is activated.

Measurement Operation

The SS4003 accumulates charge and discharge current and estimates self-discharge. Charge current is

controlled according to state-of-charge of the battery. The battery capacity is denoted as Remaining

Capacity (RCAP) in terms of relative state of charge, represents the available battery capacity at any

given time. Charging increases the RCAP. Discharging and self-discharge will decreases the RCAP. An

internal register is used to monitor the amount of discharge so as to adjust the Full Charge Capacity

(FCCAP). FCCAP is updated only if a complete cycle of battery discharge from full to empty level is

done and not interleaved by any charge operation. Therefore, the SS4003 adapts its capacity

determination based on the actual conditions of discharge. The battery's initial full capacity is set to the

value stored in a ROM. Until FCCAP is updated, RCAP counts up to, but not beyond, this threshold

during subsequent charge. The battery’s empty state is also programmed in the ROM. The battery low

percentage stores the percentage of FCCAP while the battery voltage drops to the PEV threshold.

1. Full Charge Capacity (FCCAP):

FCCAP is the latest measured discharge capacity of the battery. On initialization, FCCAP is set to the

value stored in the ROM. During subsequent discharge, FCCAP is updated with the latest recognized

complete discharging (or learning cycle), representing a discharge from full to near empty. A learning

cycle is necessary for updating the FCCAP register. The FCCAP also serves as the 100% reference

threshold used by the relative state-of-charge calculation and display.