TLE6389_07 Datasheet, PDF (35/38 Pages) Infineon Technologies AG – Step-Down DC/DC Controller

TLE 6389
7.11
Components recommendation - overview
Device
C_IN1
C_IN2
L1
M1
C_BDS
D1
C_OUT
C_COMP
Type
Electrolytic /Foil type
Ceramic
B82464-A4473
B82479-A1473-M
DO3340P-473
DO5022P-683
DS5022P-473
BSO 613SPV
BSP 613P
SPD09P06PL
Ceramic
MBRD360
MBRD340
SS34
B45197-A2107
Ceramic
Supplier
various
various
EPCOS
EPCOS
Coilcraft
Coilcraft
Coilcraft
Infineon
Infineon
Infineon
various
Motorola
Motorola
various
EPCOS
various
Remark
100µF, 60V
220nF, 60V
47µH, 1.6A, 145mΩ
47µH, 3.5A, 47mΩ
47µH, 3.8A, 110mΩ
68µH, 3.5A, 130mΩ
47µH, 4.0A, 97mΩ
60V, 3.44A, 130mΩ, NL
60V, 2.9A, 130mΩ, NL
60V, 9A, 250mΩ, LL
220nF, 16V
Schottky, 60V, 3A
Schottky, 40V, 3A
Schottky, 40V, 3A
Low ESR Tantalum, 100µF, 10V
see 7.10.9.
7.12
Layout recommendation
The most sensitive points for Buck converters - when considering the layout - are the
nodes at the input, output and the gate of the PMOS transistor and the feedback path.
For proper operation and to avoid stray inductance paths the external catch diode, the
Buck inductance and the input capacitor C_IN1 have to be connected as close as possible to
the PMOS device. Also the GDRV path from the controller to the MosFet has to be as short
as possible. Best suitable for the connection of the cathode of the catch diode and one
terminal of the inductance would be a small plain located next to the drain of the PMOS.
The GND connection of the catch diode must be also as short as possible. In general the
GND level should be implemented as surface area over the whole PCB as second layer,
if necessary as third layer. The feedback path has to be well grounded also, a ceramic
capacitance might help in addition to the output cap to avoid spikes.
To obtain the optimum filter capability of the input pi-filter it has to be located also as
close as possible to the input. To filter the supply input of the device (VS) the ceramic cap
should be connected directly to the pin.
As a guideline an EMC optimized application board / layout is available.
Datasheet Rev. 2.1
35
2007-08-13