Rainbow Electronics MAX16825 - Manual (Page 7)

Detailed Description
The MAX16824/MAX16825 are three-channel LED dri-
vers that operate from a 6.5V to 28V input voltage
range. These devices provide three independent open-
drain, constant-current-sinking outputs rated to 36V
and deliver up to 150mA of current to each HB LED
string. The current in each channel is programmable
using an external current-sense resistor in series with
each internal power MOSFET’s source. The MAX16824
features three separate PWM inputs that allow a wide
range of independent dimming level at each of the
three outputs. The PWM inputs also function as on/off
control inputs for each corresponding output (Figure 1).
The MAX16825 includes a 4-wire serial interface to
control the state of each output (Figure 2).
The 4-wire serial interface comprises a 3-bit shift regis-
ter and a 3-bit transparent latch. The shift register is
updated using a clock input CLK and a data input DIN.
DOUT is the last bit of the shift register. This feature
allows multiple drivers to be cascaded and operated
together. The latch is transparent from the shift register
outputs to the LED output when LE is high while it latch-
es the shift register state on the falling edge of LE. The
output-enable input OE allows simultaneous enabling
or disabling of all three outputs.
MAX16824/MAX16825
High-Voltage, Three-Channel Linear
High-Brightness LED Drivers
_______________________________________________________________________________________ 7
BANDGAP AND
5V REGULATOR
THERMAL
SHUTDOWN
200mV
OUT1
OUT2
OUT3
CS1
CS2
CS3
PWM1
REG
IN
GND
PWM2
PWM3
PWM
CONTROL AND
LOGIC
MAX16824
Figure 1. Internal Block Diagram (MAX16824)