LT1959 LINER [Linear Technology], LT1959 Datasheet - Page 15

• Manufacturer Part Number: LT1959
• Description: 4.5A, 500kHz Step-Down Switching Regulator
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
from the switch node. Also note that the high current
ground path of the catch diode and input capacitor are kept
very short and separate from the analog ground line.
The high speed switching current path is shown schemati-
cally in Figure 6. Minimum lead length in this path is
essential to ensure clean switching and low EMI. The path
including the switch, catch diode, and input capacitor is
GROUND PLANE
CONNECT TO
GND
AWAY FROM HIGH FREQUENCY,
KEEP FB AND V
HIGH CURRENT COMPONENTS
AROUND GND PIN FOR GOOD
V
THERMAL CONDUCTIVITY
IN
PLACE FEEDTHROUGHS
U
INFORMATION
C
U
COMPONENTS
W
C3
MINIMIZE LT1959 C3, D1 LOOP
Figure 5. Suggested Layout (Topside Only Shown)
C1
V
IN
1
Figure 6. High Speed Switching Path
R2
R3
U
U1
CIRCULATING
FREQUENCY
SWITCH NODE
PATH
HIGH
D1
D2
C4
the only one containing nanosecond rise and fall times. If
you follow this path on the PC layout, you will see that it is
irreducibly short. If you move the diode or input capacitor
away from the LT1959, get your resumé in order. The
other paths contain only some combination of DC and
500kHz triwave, so are much less critical.
L1
L1
C5
LOAD
1959 F06
GROUND PLANE
5V
CONNECT TO
GND
KELVIN SENSE
V
OUT
V
C6
OUT
DIRECTLY FROM
END OF OUTPUT
LT1959
TAKE OUTPUT
CAPACITOR
15
1959 F05