MAX6978
8-Port, 5.5V Constant-Current LED Driver with
LED Fault Detection and Watchdog
4 _______________________________________________________________________________________
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS
OFF, R
SET
= 720Ω)
MAX6978 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +125°C
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
4.2
4.5
4.4
4.3
4.6
4.7
4.8
4.9
5.0
5.1
5.2
3.0 4.03.5 4.5 5.0 5.5
MAX6978 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
T
A
= +125°C
T
A
= +85°C
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS
OFF, R
SET
= 360Ω)
T
A
= -40°C
T
A
= +25°C
0
3
9
6
12
15
3.0 4.03.5 4.5 5.0 5.5
MAX6978 toc03
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS
ON, R
SET
= 720Ω)
T
A
= +125°C
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
3.3V TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 3V to 5.5V, T
A
= T
MIN
to T
MAX
, unless otherwise noted.) (Note 1)
SYMBOL
MIN TYP MAX
CLK Clock Period t
CP
52 ns
CLK Pulse-Width High t
CH
24 ns
CLK Pulse-Width Low t
CL
24 ns
DIN Setup Time t
DS
4ns
DIN Hold Time t
DH
8ns
DOUT Propagation Delay t
DO
12 48 ns
DOUT Rise and Fall Time C
DOUT
= 10pF, 20% to 80% 10 ns
LE Pulse-Width High t
LW
20 ns
LE Pulse Width (Fault-Detection
Data Valid)
t
LW
20 ns
LE Setup Time t
LS
15 ns
LE Rising to OUT_ Rising Delay 100 ns
LE Rising to OUT_ Falling Delay 310 ns
CLK Rising to OUT_ Rising Delay
CLK Rising to OUT_ Falling Delay
OE Rising to OUT_ Rising Delay
OE Falling to OUT_ Falling Delay
t
OEL
330 ns
LED Output OUT_ Turn-On Fall
Time
t
f
80% to 20% 200 ns
LED Output OUT_ Turn-Off Rise
Time
t
r
20% to 80% 120 ns
Note 1: All parameters tested at T
A
= +25°C. Specifications over temperature are guaranteed by design.
Note 2: See Figure 3.