LTC4244 LINER [Linear Technology], LTC4244 Datasheet - Page 22

• Manufacturer Part Number: LTC4244
• Description: Rugged, CompactPCI Bus Hot Swap Controllers
• Manufacturer: LINER [Linear Technology]

LTC4244/LTC4244-1
APPLICATIO S I FOR ATIO
PCB Layout Considerations
For proper operation of the LTC4244’s circuit breaker,
4-wire Kelvin sense connections between the sense resis-
tor and the LTC4244’s 5V
and 3.3V
layout should be balanced and symmetrical to minimize
wiring errors. In addition, the PCB layout for the sense
resistors and the power MOSFETs should include good
thermal management techniques for optimal device power
dissipation. A recommended PCB layout for the sense
resistor, the power MOSFET and the GATE drive compo-
nents around the LTC4244 is illustrated in Figure 15. In Hot
22
SENSE
Figure 15. Recommended Layout for Power MOSFET, Sense Resistor and GATE Components for the 3.3V Rail
pins are strongly recommended. The PCB
U
3.3V
3.3V
GND
IN
U
IN
and 5V
TRACK WIDTH W:
0.03" PER AMPERE
ON 1 OZ Cu FOIL
*ADDITIONAL DETAILS OMITTED FOR CLARITY
DRAWING IS NOT TO SCALE!
CURRENT FLOW
TO LOAD
W
W
W
SENSE
pins and 3.3V
RESISTOR
SENSE
U
C
LTC4244*
TIMER
IN
GATE
CURRENT FLOW
Swap applications where load currents can be 10A, nar-
row PCB tracks exhibit more resistance than wider tracks
and operate at more elevated temperatures. Since the
sheet resistance of 1 ounce copper foil is approximately
0.45m / , track resistance and voltage drops add up
quickly in high current applications. Thus, to keep PCB
track resistance, voltage drop and temperature to a mini-
mum, the suggested trace width in these applications for
1 ounce copper foil is 0.03” for each ampere of DC current.
In the majority of applications, it will be necessary to use
plated-through vias to make circuit connections from
component layers to power and ground layers internal to
TO SOURCE
D
D
D
D
R3
R5
SO-8
C1
G
S
S
S
CURRENT FLOW
TO LOAD
W
VIA/PATH
TO GND
VIA TO
GND PLANE
4244 F15
3.3V
3.3V
GND
OUT
42441f