Datasheet

Stand-Alone Operation
In stand-alone operation, the MAX16809 does not use
the 4-wire interface (see the Typical Operating Circuits).
Connect DIN and LE to V+ and provide at least 16
external clock pulses to CLK to enable 16 output ports.
This startup pulse sequence can be provided either using
an external clock or the PWM signal. The external clock
can also be generated using the signal at RTCT and an
external comparator.
LED Dimming
PWM Dimming
All the output channels can be dimmed simultaneously
by applying a PWM signal (50Hz to 30kHz) to OE. This
allows for a wide range of dimming up to a 5000:1 ratio.
Each channel can be independently turned on and off
using a 4-wire serial interface. The dimming is proportion-
al to the PWM duty cycle.
LED Current Amplitude Adjustment
Using an analog or digital potentiometer as RSET allows
for LED current amplitude adjustment and linear dimming.
Computing Power Dissipation
Use the following equation to estimate the upper limit
power dissipation (PD) for the MAX19:
i 15
OUTi OUTi
i 0
CC CC
PD DUTY (V x I ) V x I
(V x I )
=
=

= × + ++
∑


+
where:
V+ = supply voltage
I+ = V+ operating supply current
DUTY = PWM duty cycle applied to OE
V
OUTi
= MAX16809 port output voltage when driving load
LED(s)
IOUTi = LED drive current programmed by R
SET
PD = power dissipation
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer board
whenever possible for better noise immunity. Protect
sensitive analog grounds by using a star ground con-
figuration. Minimize ground noise by connecting AGND,
PGND, the input bypass-capacitor ground lead, and the
output-filter ground lead to a single point (star ground con-
figuration). Also, minimize trace lengths to reduce stray
capacitance, trace resistance, and radiated noise. The
trace between the output voltage-divider and the FB pin
must be kept short, as well as the trace between AGND
and PGND.
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Maxim Integrated │ 17
MAX16809 Integrated 16-Channel LED Driver with
Switch-Mode Boost and SEPIC Controller