MAX16809_09 Datasheet, PDF (16/20 Pages) Maxim Integrated Products – Integrated 16-Channel LED Driver with Switch-Mode Boost and SEPIC Controller

Integrated 16-Channel LED Driver with
Switch-Mode Boost and SEPIC Controller
LE
CLK
DIN
DOUT
t_CL
t_CH
t_DH
t_DS
D15
D14
t_LW
t_LS
t_CP
D1
t_DO
D0
D15
OE
OUT_ _
Figure 3. 4-Wire Serial-Interface Timing Diagram
t_OEW
t_OEF
t_F
t_OER
80%
20%
t_R
LE
t_LRF
OUT_ _
LE
t_LRR
OUT_ _
CLK
t_CRF
OUT_ _
CLK
t_CRR
OUT_ _
Figure 4. LE and CLK to OUT_ _ Timing
Selecting External Component
R_SET to Set LED Output Current
The MAX16809 uses an external resistor, R_SET, to set
the LED current for outputs OUT0–OUT15. The mini-
mum allowed value of R_SET is 311Ω, which sets the out-
put currents to 55mA. The maximum allowed value of
R_SET is 5kΩ (I_{OUT_ _} = 3.6mA) and the maximum
allowed capacitance at SET is 100pF.
Use the following formula to set the output current:
R_SET
=
17,100V
I_{OUT _ _}
where I_{OUT_ _} is the desired output current in milliamps
and the value for R_SET is in ohms.
Overtemperature Cutoff
The MAX16809 contains an internal temperature sensor
that turns off all outputs when the die temperature
exceeds +165°C. The outputs are enabled again when
the die temperature drops below +140°C. Register con-
tents are not affected, so when a driver is overdissipat-
ing, the external symptom is the load LEDs cycling on
and off as the driver repeatedly overheats and cools,
alternately turning itself off and then back on again.
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