MAX7313 Maxim, MAX7313 Datasheet - Page 20

• Manufacturer Part Number: MAX7313
• Description: The MAX7313 I²C-compatible serial interfaced peripheral provides microprocessors with 16 I/O ports
• Manufacturer: Maxim

blink phases (Tables 8 and 9). The effect of setting an
output’s blink phase x register bit to 0 or 1 is shown in
Table 12. LEDs can be flipped between either directly on
and off, or between a variety of high/low PWM intensities.
The 4 bits used for output O16’s PWM individual inten-
sity setting also double as the global intensity control
(Table 13). Global intensity simplifies the PWM settings
when the application requires them all to be the same,
such as for backlight applications, by replacing the 17
individual settings with 1 setting. Global intensity is
enabled with the Global Intensity flag G in the configu-
ration register (Table 4). When global PWM control is
used, the 4 bits of master intensity and 4 bits of global
intensity effectively combine to provide an 8 bit, 240-
step intensity control applying to all outputs.
It is not possible to apply global PWM control to a sub-
set of the ports, and use the others as logic outputs. To
mix static logic outputs and PWM outputs, individual
PWM control must be selected (Table 10).
16-Port I/O Expander with LED Intensity
Control, Interrupt, and Hot-Insertion Protection
Table 12. PWM Intensity Settings (Blink Enabled)
20
INTENSITY
GLOBAL)
SETTING
OUTPUT
(OR
0xA
0xB
0xC
0xD
0x0
0x1
0x2
0x3
0x4
0x5
0x6
0x7
0x8
0x9
0xE
0xF
______________________________________________________________________________________
Static low
PWM DUTY CYCLE
REGISTER BIT = 0
10/16
11/16
12/16
13/16
14/16
15/16
LOW
TIME
1/16
2/16
3/16
4/16
5/16
6/16
7/16
8/16
9/16
OUTPUT BLINK
PHASE X
Static low
Global/O16 Intensity Control
HIGH
15/16
14/16
13/16
12/16
11/16
10/16
TIME
9/16
8/16
7/16
6/16
5/16
4/16
3/16
2/16
1/16
impedance
Static high
PWM DUTY CYCLE
REGISTER BIT = 1
15/16
14/16
13/16
12/16
11/16
10/16
LOW
TIME
9/16
8/16
7/16
6/16
5/16
4/16
3/16
2/16
1/16
OUTPUT BLINK
PHASE X
impedance
Static high
HIGH
10/16
11/16
12/16
13/16
14/16
15/16
TIME
1/16
2/16
3/16
4/16
5/16
6/16
7/16
8/16
9/16
P hase 0: LE D on at hi g h i ntensi ty
P hase 1: LE D on at hi g h i ntensi ty
P hase 1: LE D on at l ow i ntensi ty
Phase 0: LED on continuously
Phase 1: LED off continuously
P hase 0: LE D on at l ow i ntensi ty
I/O ports P0–P15, interrupt output INT/016, and serial
interface SDA, SCL, AD0–2 remain high impedance
with up to 6V asserted on them when the MAX7313 is
powered down (V+ = 0V). The MAX7313 can therefore
be used in hot-swap applications.
The open-drain output architecture allows the ports to
level translate the outputs to higher or lower voltages
than the MAX7313 supply. An external pullup resistor
can be used on any output to convert the high-imped-
ance logic-high condition to a positive voltage level.
The resistor can be connected to any voltage up to
5.5V. For interfacing CMOS inputs, a pullup resistor
value of 220kΩ is a good starting point. Use a lower
resistance to improve noise immunity, in applications
where power consumption is less critical, or where a
faster rise time is needed for a given capacitive load.
REGISTER BIT = 0
REGISTER BIT = 1
BLINK PHASE 0
BLINK PHASE 1
Output is half intensity during both blink phases
EXAMPLES OF LED BLINK BEHAVIOR
(LED IS ON WHEN OUTPUT IS LOW)
Applications Information
Output Level Translation
P hase 0: LE D on at hi g h i ntensi ty
P hase 1: LE D on at l ow i ntensi ty
P hase 1: LE D on at hi g h i ntensi ty
Phase 0: LED off continuously
Phase 1: LED on continuously
P hase 0: LE D on at l ow i ntensi ty
REGISTER BIT = 1
REGISTER BIT = 0
BLINK PHASE 0
BLINK PHASE 1
Hot Insertion