LTM4607EV#PBF Linear Technology, LTM4607EV#PBF Datasheet - Page 14

• Manufacturer Part Number: LTM4607EV#PBF
• Description: IC BUCK/BOOST SYNC ADJ 5A 141LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM4607EV#PBF

• Design Resources: LTM4607 Spice Model
• Output: 0.8 ~ 24 V
• Number Of Outputs: 1
• Power (watts): 120W
• Mounting Type: Surface Mount
• Voltage - Input: 4.5 ~ 36 V
• Package / Case: 141-LGA
• 1st Output: 0.8 ~ 24 VDC @ 5A
• Size / Dimension: 0.59" L x 0.59" W x 0.11" H (15mm x 15mm x 2.8mm)
• Power (watts) - Rated: 120W
• Operating Temperature: -40°C ~ 85°C
• Efficiency: 98%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -

LTM4607
APPLICATIONS INFORMATION
To choose a proper inductor, we need to know the current
ripples at different input voltages. The inductor should
be chosen by considering the worst case in the practi-
cal operating region. If the maximum output power P is
120W at buck mode, we can get the current ripple ratio
of the current ripple ΔI
I
Figure 3. shows the current ripple ratio at different input
voltages based on the inductor values: 2.5μH, 3.3μH, 4.7μH
and 6μH. If we need about 40% ripple current ratio at all
inputs, the 4.7μH inductor can be selected.
At buck mode, sensing resistor selection is based on
the maximum output current and the allowed maximum
sensing threshold 130mV.
Consider the safety margin about 30%, we can choose
the sensing resistor as 9mΩ.
14
L
Figure 3. Current Ripple Ratio at Different Inputs for Buck Mode
as follows:
R
ΔI
I
SENSE
L
L
=
(V
0.8
0.6
0.4
0.2
=
0
IN
V
12
2 • (P / V
IN
V
ƒ = 400kHz
– V
OUT
• L • ƒ • P
2 • 130mV
= 12V
OUT
18
INPUT VOLTAGE V
OUT
L
) • V
to the maximum inductor current
) − ΔI
OUT
2
24
2.5μH
2.5μH
4.7μH
3.3μH
L
IN
(V)
30
6μH
4607 F03
36
For the input capacitor, use a low ESR sized capacitor to
handle the maximum RMS current. Input capacitors are
required to be placed adjacent to the module. In Figure
16, the 10μF ceramic input capacitors are selected for
their ability to handle the large RMS current into the
converter. The 100μF bulk capacitor is only needed if the
input source impedance is compromised by long inductive
leads or traces.
For the output capacitor, the output voltage ripple and
transient requirements require low ESR capacitors. If
assuming that the ESR dominates the output ripple, the
output ripple is as follows:
If a total low ESR of about 5mΩ is chosen for output
capacitors, the maximum output ripple of 21.5mV occurs
at the input voltage of 36V with the current ripple at 4.3A.
Boost Mode Operation
For boost mode operation, use input voltage V
12V, V
Set the PLLFLTR pin and R
If the maximum output power P is 60W at boost mode
and the module efficiency η is about 95%, we can get
the current ripple ratio of the current ripple ΔI
maximum inductor current I
ΔV
ΔI
I
L
L
OUT(P-P)
OUT
=
(V
= 12V and ƒ = 400kHz.
OUT
V
OUT
= ESR • ΔI
− V
• L • f • P
IN
) • V
L
IN
2
FB
η
L
as in buck mode.
as follows:
IN
L
= 5V to
to the
4607fb