MAX16839 Evaluation Kit
Evaluates:
MAX16839
4 ______________________________________________________________________________________
Use a digital PWM signal with a 5V logic level and
a switching frequency between 100Hz and 10kHz.
Frequencies lower than 100Hz can introduce flickering
in the light output. Vary the duty cycle of the signal to
adjust the LED brightness. LED brightness increases as
the duty cycle increases and vice versa. When the PWM
signal’s duty cycle is 100%, the LEDs are continuously
on. At 0% duty cycle, the outputs are disabled.
See Table 5 for configuring the DIM_ jumpers. Refer to
the
PWM Dimming
section in the MAX16839 IC data
sheet for further information on the DIM signal.
Additional Configurations and Features
The EV kit includes several other features to facilitate
evaluating the MAX16839 IC. A power-supply chopper-
circuit feature, and the ability to cascade multiple kits for
operation, are detailed in the following sections.
Chopper-Circuit Operation
The EV kit features a power-supply chopper circuit for
the VIN input supply. The input supply chopper circuit
is comprised of p-channel MOSFET P1, biasing resistor/
diode pair R7/D2, and switching transistor Q1. When
installed, jumper JU11 is provided to bypass the chop-
per circuit.
To use the chopper circuit, connect a function generator
with a digital signal to the CHOP and GND PCB pads.
Use a 3V to 5V low-frequency pulse-width-modulated
(PWM) signal to switch the chopper circuit on/off.
Cascading Multiple Kits
The EV kit features PCB pads and jumpers for cascading
multiple kits. To cascade another EV kit, use the follow-
ing guidelines:
1) Install all DIM_ shunts on jumpers JU4 and JU5.
2) Install all FLTS_ shunts on jumpers JU6 and JU7.
3) Connect the DIM3 PCB pad on kit #1 to the DIM1 PCB
pad on kit #2.
4) Connect the FLTS3 pad on kit #1 to the FLTS1 pad on
kit #2.
5) Connect the GND PCB pad nearest DIM3 on kit #1 to
the GND PCB pad nearest the DIM3 pad on kit #2.
6) Connect a common power supply to both kits’ VIN
and PGND PCB pads.
Table 5. DIM1, DIM
2, DIM3 (JU4, JU5)
Table 6. Ch
opper-Circuit Operation
(JU11)
*
Default position.
*
Default position.
SHUNT
POSITION
U1, U2, AND U3
DIM PINS
DIM
OPERATION
Installed
Connected together
Synchronous
Not installed*
Independent
Independent
SHUNT
POSITION
MOSFET P1/ BIASING
RESISTOR R8
CHOPPER-
CIRCUIT
OPERATION
Installed
Connected to ground
Bypassed
Not installed*
Connected to Q1
Running