MAX16809_09 Datasheet, PDF (11/20 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
PIN
1, 31, 32,
36, 38
2
3
4–11
12
13
14
15
16, 17
18
19
20
21–28
29
30
33
34
35
37
—
Pin Description
NAME
FUNCTION
N.C.
No Connection. Not internally connected. Leave unconnected.
FB
Error-Amplifier Inverting Input
COMP
Error-Amplifier Output
OUT8–OUT15 LED Driver Outputs. OUT8–OUT15 are open-drain, constant-current-sinking outputs rated for 36V.
OE
Active-Low, Output Enable Input. Drive OE low to PGND to enable the OUT0–OUT15. Drive OE
high to disable OUT0–OUT15.
DOUT
SET
V+
PGND
DIN
CLK
LE
OUT0–OUT7
Serial-Data Output. Data is clocked out of the 16-bit internal shift register to DOUT on CLK’s
rising edge.
LED Current Setting. Connect R_SET from SET to PGND to set the LED current.
LED Driver Positive Supply Voltage. Bypass V+ to PGND with a 0.1μF ceramic capacitor.
Power Ground
Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.
Serial-Clock Input
Latch-Enable Input. Data is loaded transparently from the internal shift register(s) to the output
latch(es) while LE is high. Data is latched into the output latch(es) on LE’s falling edge, and
retained while LE is low.
LED Driver Outputs. OUT0–OUT7 are open-drain, constant-current-sinking outputs rated for 36V.
RTCT
CS
AGND
OUT
PWM Controller Timing Resistor/Capacitor Connection. A resistor R_T from RTCT to REF and a
capacitor C_T from RTCT to AGND set the oscillator frequency.
PWM Controller Current-Sense Input
Analog Ground
MOSFET Driver Output OUT. Connects to the gate of the external n-channel MOSFET.
V_CC
Power-Supply Input. Bypass V_CC to AGND with a 0.1μF ceramic capacitor or a parallel
combination of a 0.1μF and a higher value ceramic capacitor.
REF
5V Reference Output. Bypass REF to AGND with a 0.1μF ceramic capacitor.
EP
Exposed Paddle. Connect to the ground plane for improved power dissipation. Do not use as the
only ground connection.
Detailed Description
The MAX16809 LED driver includes an internal switch-
mode controller that can be used as a boost or buck-
boost (SEPIC) converter to generate the voltage
necessary to drive the multiple strings of LEDs. This
device incorporates an integrated low-side driver, a
programmable oscillator (20kHz to 1MHz), an error
amplifier, a low-voltage (300mV) current sense for high-
er efficiency, and a 5V reference to power up external
circuitry (see Figures 1a and 1b).
The MAX16809 LED driver includes a 4-wire serial
interface and a current-mode PWM controller to gener-
ate the necessary voltage for driving 16 open-drain,
constant-current-sinking output ports. The driver uses
current-sensing feedback circuitry (not simple current
mirrors) to ensure very small current variations over the
full allowed range of output voltage (see the Typical
Operating Characteristics). The 4-wire serial interface
comprises a 16-bit shift register and a 16-bit transpar-
ent latch. The shift register is written through a clock
input, CLK, and a data input, DIN, and the data propa-
gates to a data output, DOUT. The data output allows
multiple drivers to be cascaded and operated together.
The contents of the 16-bit shift register are loaded into
the transparent latch through a latch-enable input, LE.
The latch is transparent to the shift register outputs
when high and latches the current state on the falling
edge of LE. Each driver output is an open-drain, con-
stant-current sink that should be connected to the
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