
High-Efficiency PWM LED Driver with Boost
Converter and Five Constant-Current GPIO Ports
19
MAX6948B
Figure 4. Ramp-Up Behavior
Figure 5. Hold-Off and Ramp-Down Behavior
Table 11. Port Ramp-Down Register Format (0x11)
EXIT SHUTDOWN COMMAND
FULL CURRENT/
HALF CURRENT
0
1s 2s1/4s 1/2s
1/8s
1/16s
ZERO TO 4s CURRENT RAMP-UP AFTER CS RUN
4s
ZERO TO 4s HOLD-OFF DELAY BEFORE RAMP-DOWN
ZERO TO 4s CURRENT RAMP-DOWN 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
FULL CURRENT/
HALF CURRENT
0
REGISTER DESCRIPTION
REGISTER DATA
D7 D6 D5 D4 D3 D2 D1 D0
RESERVED HOLD-OFF RAMP-DOWN
Immediately shuts down after hold-off delay X X X X X 0 0 0
0.0655s ramp-down from full current after
hold-off delay
X X X X X 0 0 1
0.131s ramp-down from full current after
hold-off delay
X X X X X 0 1 0
0.262s ramp-down from full current after
hold-off delay
X X X X X 0 1 1
0.524s ramp-down from full current after
hold-off delay
X X X X X 1 0 0
1.049s ramp-down from full current after
hold-off delay
X X X X X 1 0 1
2.097s ramp-down from full current after
hold-off delay
X X X X X 1 1 0
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