Datasheet

Global Current Register
The global current register sets the full (maximum) con-
stant current sunk into an I/O port (Table 8). Each out-
put port’s individual constant-current sink can be set to
be either half or full global current by the output current
registers (Table 7). By default, maximum current is
20mA, so the default half current is 10mA.
Ramp-Up and Ramp-Down Controls
The MAX6966/MAX6967 provide automatic controls
that allow the currents’ outputs to be ramped down into
automatic shutdown (ramp-down), and ramped up
again out of shutdown (ramp-up) without further inter-
action (Figures 4 and 5). Ramp-down comprises a pro-
grammable hold-off delay, which also maintains the
outputs at full current for a time before the programmed
fade-off time, during which the currents’ outputs are
ramped down.
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
0 XXXXX
ISET2 ISET1
ISET0
GLOBAL CURRENT
1 00000
ISET2 ISET1
ISET0
Full current is 2.5mA; half current is
1.25mA
X XXXXX000
Full current is 5mA; half current is 2.5mA
X XXXXX001
Full current is 7.5mA; half current is
3.75mA
X XXXXX010
Full current is 10mA; half current is 5mA X XXXXX011
Full current is 12.5mA; half current is
6.25mA
X XXXXX100
Full current is 15mA; half current is 7.5mA
X XXXXX101
Full current is 17.5mA; half current is
8.75mA
X XXXXX110
Full current is 20mA; half current is 10mA
X
0x15
XXXXX111
Table 8. Global Current Register Format
EXIT SHUTDOWN COMMAND
1s 2s1/4s 1/2s
1/8s
1/16s
ZERO TO 4s CURRENT RAMP-UP AFTER CS RUN
4s
Figure 4. Ramp-Up Behavior
ZERO TO 4s HOLD-OFF DELAY BEFORE FADE-OFF
ZERO TO 4s CURRENT FADE-OFF AFTER HOLD-OFF DELAY
1s 2s 4s 1s 2s
1/8s
1/16s
1/8s
1/16s
ZERO TO 8s CURRENT RAMP-DOWN
4s1/4s 1/2s 1/4s 1/2s
Figure 5. Ramp-Down, Hold-Off, and Fade-Off Behavior
MAX6966/MAX6967
18
Maxim Integrated