Datasheet

10-Port Constant-Current LED Drivers and I/O
Expanders with PWM Intensity Control
REGISTER DATA
REGISTER
R/W
ADDRESS
CODE
(HEX)
D7 D6 D5 D4 D3 D2 D1 D0
Read input ports P7–P0
1 0x0E
Port P7 Port P6 Port P5 Port P4 Port P3 Port P2 Port P1
Port P0
Read input ports P9–P8
1 0x0F 000000
Port P9
Port P8
Table 5. Input Ports Register
The stagger bit is ideally set or cleared when the
MAX6966/MAX6967 are in shutdown. If not, there may be
a perceived transient flicker in any PWM-controlled LEDs
because the fundamental PWM timing is being changed.
Configuration Register
The configuration register is used to select PWM phas-
ing between outputs, test fade status, enable hardware
startup from shutdown, and select shutdown or run
mode (Table 4).
GPIO Port Direction Configuration
The 10 I/O ports P0 through P9 can be configured to
any combination of logic inputs, logic outputs, and con-
stant-current outputs. Configure any port as a logic
input by setting its output register to 0x01, which sets
the port output high impedance (Table 6).
Input Ports Registers
Reading an input port register returns the logic levels at
the I/O port pins for ports that have been configured as a
logic input (Table 5). A port is configured as a logic input
by writing 0x01 to the port’s output register (Table 5). An
input ports register returns logic 0 in the appropriate bit
position for a port not configured as a logic input.
The input ports registers are read only. A write to an
input ports register is ignored.
Output Registers and
PWM Intensity Control
The MAX6966/MAX6967 use one 8-bit register to control
each output port (Table 6). Each port may be configured
as a logic input, open-drain logic output, or constant-cur-
rent sink with programmable current and PWM duty
cycle. Ports withstand 7V independent of the MAX6966’s
or MAX6967’s supply voltage, whether used as logic
inputs, logic outputs, or constant-current sinks.
Ports configured as constant-current outputs sink a con-
stant current set by the output current registers (Table 7)
and the global current registers (Table 8). This current
may be PWM with a duty cycle ranging from 3/256 to
254/256 to reduce the average current, or remain static.
The 10 registers 0x00 through 0x09 control an I/O port
each (Table 6). Five pseudo-register addresses, 0x0B
through 0x0F, allow groups of outputs to be set to the
same value with a single command by writing the same
data to multiple output registers.
PWM timing for LED intensity control is generated using
either the internal 32kHz oscillator, or an external clock
on DOUT/OSC. The PWM clock source is selected by
configuration register bit D7 (Table 4). The MAX6966
powers up configured to use the internal 32kHz oscilla-
tor by default. The MAX6967 powers up configured to
use the external clock source by default.
MAX6966/MAX6967
14
Maxim Integrated