Evaluate: MAX17061
White LED String Configuration
As configured, the MAX17061 EV kit is assembled with
four strings of 10 WLEDs (string 1–string 4), but can be
reconfigured to drive up to eight strings of 10 WLEDs.
Each string has an associated 3-pin header (JU1–JU8)
and feedback pin (FB1–FB8). To evaluate additional
strings (string 5–string 8), the EV kit must be reconfig-
ured as follows:
1) Populate String_ with either the WLED listed in the
Component List
, or its equivalent.
2) Cut the trace (solder side) between pins 2-3 of the
string’s associated header-footprint (JU5–JU8).
3) Install a 3-pin header (JU5–JU8) and configure its
shunt according to Table 2.
To evaluate the EV kit with off-board WLED strings, see
the
Off-Board White LED String Configuration
section.
Off-Board White LED String Configuration
The MAX17061 EV kit can also be used to drive off-
board WLED strings. To evaluate external WLED
strings, reconfigure shunts from jumpers JU1–JU8. See
Table 2 for jumpers JU1–JU8 configuration and Table 3
for jumper JU9 configuration. Removing these jumpers
effectively disconnects the on-board WLED strings
between the output and feedback pins, allowing the
connection of external WLED strings. For each external
WLED string, connect the cathode terminal of the string
to the corresponding feedback pad (FB1–FB8) and
connect the anode terminal of the string to the VOUT
pad. Once the external WLED strings are connected
between the VOUT pad and the FB_ pins, the EV kit
can be evaluated in the same manner as the on-board
WLED strings. Evaluating more than 10 WLEDs per
string may require component changes. Refer to the
MAX17061 IC data sheet for component selections.
LED String Capacitance
In some LCD panel applications, a 0.1µF (typ) capaci-
tor (CLED) is placed in parallel with each LED string
to improve ESD immunity. As such, the MAX17061 EV
kit provides a footprint across each LED string for
optional CLED.
Input Power Supply
The MAX17061 EV kit can be evaluated with one or two
input power supplies. When using one input power sup-
ply, connect a 7V to 21V power supply to the VIN pad
and configure jumper JU10 for single-supply operation
(see Table 4). In single-supply operation, do not con-
nect an external power supply or load to the VCC pad.
To utilize two input power supplies, configure jumper
JU10 for dual-supply operation and connect a 4.5V to
5.5V power supply to the VCC pad and a 7V to 21V
power supply to the VIN pad.
The MAX17061 EV kit is also capable of single-supply
operation in the 4.5V to 5.5V range. If this operation is
desired, provide an external short between IN and VCC.
Refer to the MAX17061 IC data sheet for component
selection in this condition.
Setting Full-Scale LED Current (ILED(FS))
The full-scale current through each WLED string is con-
figured by connecting the ISET pin to VCC or tying it to
GND through resistors R4 and R5. When ISET is con-
nected to VCC, the full-scale current per string is set to
25mA; when pulled to GND, the full-scale current per
string is adjustable from 15mA to 30mA:
where R4 is a 130kΩresistor and R5 is a 200kΩpoten-
tiometer. The ISET pin is configured through jumper
JU11. See Table 5 for jumper JU11 settings.