Datasheet
ADP5588 Data Sheet
Rev. C | Page 24 of 28
APPLICATIONS INFORMATION
CONTROL
REGISTERS
HOST
PROCESSOR
CONTROL
INTERFACE
REF
VOLTAGE
C9
C9
C8
C8
R7
R6
R5
R4
R3
R2
R1
R0
C0
C1
C2
C3
C4
C5
C6
C7
C9
C8
ENABLE 2 (GPO)
BACKLIGHT
ENABLE (GPO)
A0A1A2A3
A4A5A6A7
B0B1B2B3B4B5B6B7
C0C1C2C3C4C5C6C7
D0D1D2D3D4D5D6D7
E0E1E2E3E4E5E6E7
F0F1F2F3
F4F5F6F7
G0G1G2G3G4G5G6G7
H0H1H2H3H4H5H6H7
I0I1I2I3I4I5I6I7
J0J1J2J3J4J5J6J7
SCL
SDA
V
CC
GND
V
CC
SCL
GPL1
GPL2
SDA
RST
INT
19
21
23
22
18
17
20
24
1 2 3 4 5 6 7
8
9 10 11 12 13 14 15 16
REF
VOLTAGE
0.1µF
0.1µF
V
CC
V
CC
07673-022
BACKLIGHT
DRIVER
PWM OUTPUT
ADP5588
V
CC
RST
INT
Figure 17. ADP5588 Detailed Application Block Diagram
APPLICATIONS OVERVIEW
The ADP5588 is designed to complement host processors in a
variety of ways. Its versatility makes it the ideal solution for
mobile platforms that require extended keypads and GPIO
expanders. The programmable registers give the designer the
flexibility to configure any or all its GPIOs in a variety of ways.
Figure 17 shows a detailed application diagram.
KEYPAD CURRENT
Keypad current drain varies based on how many keys and how
many rows and columns are pressed during multiple key presses.
Table 52 shows typical current drain for a single press and for
two key presses.
Table 52. Typical Current Drain
Key Presses Conditions
1
Typical Unit
1
V
CC
= 1.8 V to 3.0 V
55
μA
2 V
CC
= 1.8 V to 3.0 V 100 μA
1
T
A
= T
J
= −40°C to +85°C.
BACKLIGHT CONTROL APPLICATION
Although the ADP5588 is not designed with a backlight driver,
the built-in light sensor comparator inputs, with programmable
registers and trip points, give the backlight designer all the
necessary tools to control the backlight based on lighting con-
ditions or environment. With a few I
2
C commands, the designer
can program the device to monitor lighting conditions and
trigger an interrupt based on preset trip points. Once program-
med, the state machine uses these trip points and hysteresis
values to alert the microprocessor of any change in lighting
conditions. In addition to the L2_OUT and L3_OUT bits, four
additional registers (Register 0x3B through Register 0x3E, two
registers per light sensor) provide detailed accounts of the
internal ADC due to light condition changes. The ADC has a
full-scale current of 1000 μA and a dynamic range of 8000,
which translates to 0.125 μA or 0.3125 lux per step. These two
corresponding registers per sensor form a 13-bit register that
can be read to provide detailed translation of the light sensor
input at any instant.