MAX6966 Maxim, MAX6966 Datasheet - Page 18

• Manufacturer Part Number: MAX6966
• Description: The MAX6966/MAX6967 serial-interfaced peripherals provide microprocessors with 10 I/O ports rated to 7V
• Manufacturer: Maxim

10-Port Constant-Current LED Drivers and I/O
Expanders with PWM Intensity Control
The global current register sets the full (maximum) con-
stant current sunk into an I/O port
put port’s individual constant-current sink can be set to
be either half or full global current by the output current
registers
20mA, so the default half current is 10mA.
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
grammable hold-off delay, which also maintains the
outputs at full current for a time before the programmed
Table 8. Global Current Register Format
Figure
18
Full current is 2.5mA; half current is
1.25mA
Full current is 5mA; half current is 2.5mA
Full current is 7.5mA; half current is
3.75mA
Full current is 10mA; half current is 5mA
Full current is 12.5mA; half current is
6.25mA
Full current is 15mA; half current is 7.5mA
Full current is 17.5mA; half current is
8.75mA
Full current is 20mA; half current is 10mA
______________________________________________________________________________________
5. Ramp-Down, Hold-Off, and Fade-Off Behavior
(Figures
GLOBAL CURRENT
(Table
Ramp-Up and Ramp-Down Controls
1/4s 1/2s
1/8s
1/16s
REGISTER
4 and 5). Ramp-down comprises a pro-
7). By default, maximum current is
ZERO TO 4s HOLD-OFF DELAY BEFORE FADE-OFF
1s
Global Current Register
2s
(Table
R/W
X
X
X
X
X
X
X
X
0
1
8). Each out-
CODE (HEX)
ADDRESS
ZERO TO 8s CURRENT RAMP-DOWN
0x15
4s
1/4s 1/2s
fade-off time, during which the currents’ outputs are
ramped down.
D7
Figure
1/8s
1/16s
X
0
X
X
X
X
X
X
X
X
ZERO TO 4s CURRENT FADE-OFF AFTER HOLD-OFF DELAY
1/4s 1/2s
4. Ramp-Up Behavior
1/8s
1/16s
D6
X
X
X
X
X
X
X
X
X
0
EXIT SHUTDOWN COMMAND
1s
D5
X
X
X
X
X
X
X
X
X
0
ZERO TO 4s CURRENT RAMP-UP AFTER CS RUN
1s
REGISTER DATA
2s
D4
X
0
X
X
X
X
X
X
X
X
2s
D3
X
X
X
X
X
X
X
X
X
0
ISET2 ISET1 ISET0
ISET2 ISET1 ISET0
D2
0
0
0
0
1
1
1
1
D1
0
0
1
1
0
0
1
1
4s
4s
D0
0
1
0
1
0
1
0
1