DS2788K Maxim Integrated, DS2788K Datasheet - Page 20

• Manufacturer Part Number: DS2788K
• Description: Power Management IC Development Tools
• Manufacturer: Maxim Integrated
• Series: DS2788r

All Special Feature register bits are read and write acces-
sible, with default values specified in each bit definition.
Stand-Alone Fuel-Gauge IC with
LED Display Drivers
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 button connected to
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 20. Special Feature Register Format
20
______________________________________________________________________________________
ADDRESS
Reserved
PIOSC
Field
Bit
1:7
0
Fuel-Gauge Display
15h
Read/Write
Format
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
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