MAX1652 Datasheet, PDF (25/28 Pages) Maxim Integrated Products – High-Efficiency, PWM, Step-Down DC-DC Controllers in 16-Pin QSOP

High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
of top-layer copper, so that they don’t go through
vias. The resulting top-layer “sub-ground-plane” is
connected to the normal inner-layer ground plane at
the output ground terminals. This ensures that the
analog GND of the IC is sensing at the output termi-
nals of the supply, without interference from IR
drops and ground noise. Other high-current paths
should also be minimized, but focusing ruthlessly
on short ground and current-sense connections
eliminates about 90% of all PC board layout diffi-
culties. See the evaluation kit PC board layouts for
examples.
2) Place the IC and signal components. Keep the main
switching node (LX node) away from sensitive ana-
log components (current-sense traces and REF and
SS capacitors). Placing the IC and analog compo-
nents on the opposite side of the board from the
power-switching node is desirable. Important: the
IC must be no farther than 10mm from the current-
sense resistor. Keep the gate-drive traces (DH, DL,
and BST) shorter than 20mm and route them away
from CSH, CSL, REF, and SS.
3) Employ a single-point star ground where the input
ground trace, power ground (subground plane),
and normal ground plane all meet at the output
ground terminal of the supply.
FAT, HIGH-CURRENT TRACES
MAIN CURRENT PATH
SENSE RESISTOR
MAX1652
MAX1653
MAX1654
MAX1655
Figure 9. Kelvin Connections for the Current-Sense Resistor
TOP VIEW
SS 1
(SECFB) SKIP 2
REF 3
GND 4
SYNC 5
SHDN 6
FB 7
CSH 8
MAX1652
MAX1653
MAX1654
MAX1655
( ) ARE FOR MAX1652/MAX1654.
QSOP
16 DH
15 LX
14 BST
13 DL
12 PGND
11 VL
10 V+
9 CSL
Pin Configurations
SS 1
SKIP 2
REF 3
GND 4
SYNC 5
SHDN 6
FB 7
CSH 8
MAX1653
MAX1655
16 DH
15 LX
14 BST
13 DL
12 PGND
11 VL
10 V+
9 CSL
Narrow SO
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