LTM4602 LINER [Linear Technology], LTM4602 Datasheet - Page 16

• Manufacturer Part Number: LTM4602
• Description: 6A High Effi ciency DC/DC ?Module
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Layout Checklist/Example
The high integration of the LTM4602 makes the PCB board
layout very simple and easy. However, to optimize its electri-
cal and thermal performance, some layout considerations
are still necessary.
• Use large PCB copper areas for high current path,
• Place high frequency ceramic input and output capaci-
• Place a dedicated power ground layer underneath
• To minimize the via conduction loss and reduce module
• Do not put vias directly on pads unless they are capped.
LTM4602
Table 3. 1.5V Output
16
including V
PCB conduction loss and thermal stress.
tors next to the V
high frequency noise.
the unit.
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
AIR FLOW (LFM)
200
400
200
400
0
0
IN
, PGND and V
7
6
5
4
3
1
0
2
50
Figure 16. 12V to 3.3V, No Heat Sink
IN
, PGND and V
0LFM
200LFM
400LFM
60
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
HEAT SINK
TEMPERATURE (°C)
None
None
None
70
OUT
. It helps to minimize the
80
OUT
pins to minimize
90
4602 F16
θ
JA
100
10.25
15.2
13.9
11.3
(°C/W)
14
12
Table 4. 3.3V Output
• Use a separated SGND ground copper area for com-
Figure 18 gives a good example of the recommended
layout.
LTM4602 Frequency Adjustment
The LTM4602 is designed to typically operate at 850kHz
across most input and output conditions. The control ar-
chitecture is constant on time valley mode current control.
The f
optional 1000pF capacitor. The switching frequency has
been optimized to maintain constant output ripple over the
operating conditions. The equations for setting the operat-
ing frequency are set around a programmable constant on
time. This on time is developed by a programmable current
into an on board 10pF capacitor that establishes a ramp
that is compared to a voltage threshold equal to the output
voltage up to a 2.4V clamp. This I
I
ON
ponents connected to signal pins. Connect the SGND
to PGND underneath the unit.
AIR FLOW (LFM)
= (V
ADJ
IN
200
400
200
400
0
0
pin is typically left open or decoupled with an
– 0.7V)/110k, with the 110k onboard resistor
7
6
5
4
3
2
1
0
50
Figure 17. 12V to 3.3V, BGA Heat Sink
0LFM
200LFM
400LFM
60
TEMPERATURE (°C)
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
70
HEAT SINK
None
None
None
80
ON
90
current is equal to:
4602 F16
100
θ
JA
15.2
14.6
13.4
13.9
11.1
10.5
(°C/W)
4602fa