LTM4602HVEV#PBF Linear Technology, LTM4602HVEV#PBF Datasheet - Page 17

• Manufacturer Part Number: LTM4602HVEV#PBF
• Description: IC DC/DC UMODULE 6A 104-LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM4602HVEV#PBF

• Design Resources: LTM4602HV Spice Model
• Output: 0.6 ~ 5 V
• Number Of Outputs: 1
• Power (watts): 30W
• Mounting Type: Surface Mount
• Voltage - Input: 4.5 ~ 28 V
• Package / Case: 104-LGA
• 1st Output: 0.6 ~ 5 VDC @ 6A
• Size / Dimension: 0.59" L x 0.59" W x 0.11" H (15mm x 15mm x 2.8mm)
• Power (watts) - Rated: 30W
• Operating Temperature: -40°C ~ 85°C
• Efficiency: 92%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -

APPLICATIO S I FOR ATIO
current into an on board 10pF capacitor that establishes
a ramp that is compared to a voltage threshold that is
equal to the output voltage up to a 2.4V clamp. This I
current is equal to: I
onboard resistor from V
t
is equal to: Freq. = DC/t
to V
tional to V
relatively constant frequency as the duty cycle adjustment
takes place with lowering V
to V
tively constant with different output voltages up to 2.4V.
The regulator switching period is comprised of the on
time and off time as depicted in Figure 21. The on time is
equal to t
frequency is equal to: Frequency = DC/t
ON
= (V
OUT
IN
, and the regulator duty cycle is inversely propor-
C
OUT
up to a 2.4V clamp. This will hold frequency rela-
IN
ON
IN
V
PGND
IN
/I
, therefore the step-down regulator will remain
Figure 20. Recommended PCB Layout
= (V
ON
(DC) DUTY CYCLE =
LOAD
t
) • 10pF and t
OFF
OUT
PERIOD t
U
ON
/I
V
ON
OUT
= (V
ON
IN
s
Figure 21
) • 10pF and t
. The I
U
t
ON
to f
TOP LAYER
IN
IN
t
ON
t
s
OFF
. The on time is proportional
– 0.7V)/110k, with the 110k
ADJ
ON
= t
. The on time is equal to
4602HV F21
DC =
FREQ =
current is proportional
s
W
– t
t
ON
t
s
OFF
ON
t
DC
ON
ON
=
V
4602HV F20
. The frequency
V
).
= t
OUT
IN
s
– t
U
ON
. The
ON
The LTM4602 has a minimum (t
onds and a minimum (t
The 2.4V clamp on the ramp threshold as a function of
V
ratio of V
the fact the on time will not increase as V
past 2.4V. Therefore, if the nominal switching frequency
is 850kHz, then the switching frequency will increase
to ~1.2MHz for 3.3V, and ~1.7MHz for 5V outputs due
to Frequency = (DC/t
increases to 1.2MHz, then the time period ts is reduced
to ~833 nanoseconds and at 1.7MHz the switching period
reduces to ~588 nanoseconds. When higher duty cycle
conversions like 5V to 3.3V and 12V to 5V need to be
accommodated, then the switching frequency can be
lowered to alleviate the violation of the 400ns minimum
off time. Since the total switching period is t = t
t
from the f
the on time generator, thus allowing for a longer on time
and a lower switching frequency. 12V to 5V and 5V to
3.3V derivations are explained in the data sheet to lower
switching frequency and accommodate these step-down
conversions.
Equations for setting frequency: V
t
1MHz frequency or 1µs period is chosen.
t
band.
OFF
OFF
ON
OUT
I
frequency = (I
DC = duty cycle, duty cycle is (V
t = t
switching period; t = 1/frequency
t
t
t
ON
ON
ON
OFF
and t
will be below the 400ns minimum off time. A resistor
must be greater than 400ns, or t – t
will cause the switching frequency to increase by the
= (V
= DC • t
= 0.41 • 1µs ≅ 410ns
= 1µs – 410ns ≅ 590ns
ON
OFF
OUT
ADJ
IN
+ t
are above the minimums with adequate guard
/2.4V for 3.3V and 5V outputs. This is due to
– 0.7V)/110k; for 12V input, I
pin to ground can shunt current away from
OFF
, t
ON
ON
/[2.4V • 10pF]) • (DC) = 1.79MHz;
ON
= on-time, t
OFF
) When the switching frequency
) off time of 400 nanoseconds.
ON
) on time of 100 nanosec-
LTM4602HV
OUT
OUT
OFF
= 5V
/V
= off-time of the
ON
IN
)
OUT
ON
> 400ns.
= 103µA
increases
ON
17
+ t
4602hvf
OFF
,