DS2788 MAXIM [Maxim Integrated Products], DS2788 Datasheet - Page 19

• Manufacturer Part Number: DS2788
• Description: Stand-Alone Fuel-Gauge IC with LED Display Drivers
• Manufacturer: MAXIM [Maxim Integrated Products]

All Special Feature register bits are read and write acces-
sible, with default values specified in each bit definition.
The DS2788 provides five open-drain drivers capable
of sinking 30mA. These can be used to directly drive
either 4 or 5 LEDs to display Remaining Active Relative
Pack Capacity (RARC). The LEDs are enabled when
the PIO is configured as an input and the PIO pin rec-
ognizes a rising edge. The display lights for 4s and
then is disabled regardless of the state of the PIO pin.
Further presses or releases of the PIO pin after the
100ms debounce delay causes the display to be
enabled (the display does not light continuously if the
button is held down).
Table 2 summarizes how the LEDs are enabled. B sig-
nifies that the LED is blinking at a 50% duty cycle, 0.5s
on, 0.5s off, to be repeated for the display time of 4s. L
signifies the pin is pulled low, and the LED is lit. X signi-
fies the pin is high impedance, and the LED is unlit.
Figure 16. Special Feature Register Format
ADDRESS
Reserved
PIOSC
Field
______________________________________________________________________________________
1:7
Bit
0
Fuel-Gauge Display
15h
Read/Write
Format
Stand-Alone Fuel-Gauge IC with
Undefined
PIO Sense and Control
Read values:
0: PIO pin
1: PIO pin
Write values:
0: Activates PIO pin open-drain output driver, forcing the PIO pin low.
1: Disables the output driver, allowing the PIO pin to be pulled high or used as
Power-up and SLEEP mode default: 1 (PIO pin is high-Z).
Note: PIO pin has weak pulldown.
an input.
V
V
IL
IH
Table 2. Fuel-Gauge Display Summary
80 < RARC
10 < RARC
20 < RARC
25 < RARC
40 < RARC
50 < RARC
60 < RARC
75 < RARC
CAPACITY
RARC
LED Display Drivers
Allowable Values
BIT DEFINITION
10
100
20
25
40
50
60
75
80
Special Feature Register
5 LEDs, DC: 0
LED5–LED1
XXXXB
XXXXL
XXXLL
XXXLL
XXLLL
XXLLL
XLLLL
XLLLL
LLLLL
4 LEDs, DC: 1
LED4–LED1
XXXB
XXXL
XXXL
XXLL
XXLL
XLLL
XLLL
LLLL
LLLL
19