MAX16839 Evaluation Kit
Evaluates:
MAX16839
2 ______________________________________________________________________________________
Quick Start
Required Equipment
•
5V to 40V, 500mA adjustable DC power supply
•
Three series-connected HB LED strings rated no
less than 100mA and a maximum forward voltage
of 39V
•
See the
LED Load Configuration
section for more
information
Procedure
The MAX16839 EV kit is fully assembled and tested.
Follow these steps to verify board operation.
Caution:
Do not turn on the power supply until all connections
are completed.
1) Verify that shunts are installed on pins 1-2 of jumpers
JU1, JU2, and JU3 (100mA operation).
2) Verify that shunts are not installed on jumpers
JU4–JU10 (independent operation).
3) Verify that a shunt is installed on jumper JU11
(bypass chopper circuit).
4) Set the power-supply output to 12V and disable the
output. If the total forward voltage of the HB LED
string is > 6.5V, ensure that the input supply rises in
less than 14
F
s, or connect the FLTS output to ground
to disable the turn-off in case of fault feature. The IC
can otherwise latch in fault condition at startup.
5) Connect the power-supply ground to the PGND PCB
pad.
6) Connect the power-supply positive output to the VIN
PCB pad.
7) Connect each HB LED string as follows:
Channel 1: Connect an HB LED string anode to
the LED1+ PCB pad and the cathode to the LED1-
PCB pad.
Channel 2: Connect an HB LED string anode to
the LED2+ PCB pad and the cathode to the LED2-
PCB pad.
Channel 3: Connect an HB LED string anode to
the LED3+ PCB pad and the cathode to the LED3-
PCB pad.
8) Enable the power-supply output.
9) Verify that the attached LEDs are illuminated.
Detailed Description of Hardware
The MAX16839 EV kit demonstrates three separate high-
voltage, single-channel, linear HB LED drivers. Each lin-
ear current driver circuit uses a MAX16839 IC in a 6-pin
TDFN surface-mount package with an exposed pad
for enhanced thermal dissipation. On the EV kit, each
driver circuit is configured to supply an HB LED cur-
rent of 100mA per channel at 5% current accuracy. The
MAX16839 ICs control the HB LED current by maintain-
ing a 203mV (typ) drop across each channel’s external
sense resistors (R1 or R2 for channel 1, R3 or R4 for
channel 2, and R5 or R6 for channel 3). Additionally,
each channel can be reconfigured to provide down to
50mA of current.
The EV kit operates from a 5V to 40V rated power sup-
ply providing up to 300mA and the EV kit can with-
stand a 45V load-dump condition. The input supply is
filtered by common-mode choke L1 and capacitor C1,
while battery-reverse protection is provided by diode
D1. The input supply chopper circuit is comprised of
p-channel MOSFET P1, biasing resistor/diode pair R7/
D2, and switching transistor Q1. See the
Chopper-Circuit
Operation
section for more information on using the
chopper circuit.
The MAX16839 PWM dimming-control feature can be
evaluated with an independent PWM input on each of
the three channels. Each PWM input accepts a digital
signal up to 10kHz at the DIM1, DIM2, or DIM3 and
GND PCB pads. Additionally, each PWM input functions
as an active-high enable for the corresponding chan-
nel. Multiple EV kits can be cascaded using the FLTS1,
FLTS2, FLTS3, and GND PCB pads and configuring the
proper jumpers. Jumpers JU8, JU9, and JU10 disable
the MAX16839 fault-detection features.
Each MAX16839 IC features an exposed pad that uses
the top-layer and bottom-layer PCB copper as a heat-sink.
For a single-layer design, the top-layer copper would only
be required from a thermal-design perspective. The EV
kit PCB uses 2oz copper for optimum thermal dissipation.
Note:
Indicate that you are using the MAX16839 when contacting these component suppliers.
Component Suppliers
SUPPLIER
PHONE
WEBSITE
Central Semiconductor Corp.
631-435-1110
www.centralsemi.com
Fairchild Semiconductor
888-522-5372
www.fairchildsemi.com
Murata Electronics North America, Inc.
770-436-1300
www.murata-northamerica.com
TDK Corp.
847-803-6100
www.component.tdk.com