MAX16818_09 Datasheet, PDF (24/25 Pages) Maxim Integrated Products – 1.5MHz, 30A High-Efficiency, LED Driver with Rapid LED Current Pulsing

1.5MHz, 30A High-Efficiency, LED Driver
with Rapid LED Current Pulsing
PCB Layout Guidelines
Use the following guidelines to layout the switching volt-
age regulator:
1) Place the IN, V_CC, and V_DD bypass capacitors
close to the MAX16818.
2) Minimize the area and length of the high current
loops from the input capacitor, upper switching
MOSFET, inductor, and output capacitor back to
the input capacitor negative terminal.
3) Keep short the current loop formed by the lower
switching MOSFET, inductor, and output capacitor.
4) Place the Schottky diodes close to the lower
MOSFETs and on the same side of the PCB.
5) Keep the SGND and PGND isolated and connect
them at one single point.
6) Run the current-sense lines CSP and CSN very
close to each other to minimize the loop area.
Similarly, run the remote voltage-sense lines
SENSE+ and SENSE- close to each other. Do not
cross these critical signal lines through power cir-
cuitry. Sense the current right at the pads of the
current-sense resistors.
7) Avoid long traces between the V_DD bypass capaci-
tors, the driver output of the MAX16818, the MOS-
FET gates, and PGND. Minimize the loop formed by
the V_CC bypass capacitors, bootstrap diode, boot-
strap capacitor, the MAX16818, and the upper
MOSFET gate.
8) Distribute the power components evenly across the
board for proper heat dissipation.
9) Provide enough copper area at and around the
switching MOSFETs, inductor, and sense resistors
to aid in thermal dissipation.
10) Use wide copper traces (2oz) to keep trace induc-
tance and resistance low to maximize efficiency.
Wide traces also cool heat-generating components.
Pin Configuration
TOP VIEW
21 20 19 18 17 16 15
SGND 22
SENSE- 23
SENSE+ 24
SGND ²⁵
IN 26
MAX16818
V_CC 27
V_DD 28
* EXPOSED PAD
+
12 34 5 67
14 LIM
13 V_IOUT
12 RT/SYNC
11 EN
10 PGOOD
9 CLKOUT
8 SGND
TQFN
Chip Information
TRANSISTOR COUNT: 5654
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
28 TQFN
T2855-3
21-0140
24 ______________________________________________________________________________________