LT3757MPMSE#TRPBF Linear Technology, LT3757MPMSE#TRPBF Datasheet - Page 24

• Manufacturer Part Number: LT3757MPMSE#TRPBF
• Description: IC DC-DC CTRLR ADJ 10MSOP
• Manufacturer: Linear Technology
• Type: Step-Up (Boost), Inverting, Flyback, Sepicr

Specifications of LT3757MPMSE#TRPBF

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Frequency - Switching: 100kHz ~ 1MHz
• Voltage - Input: 2.9 ~ 40 V
• Operating Temperature: -55°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP Exposed Pad, 10-HMSOP, 10-eMSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Output: -
• Power - Output: -

LT3757
applicaTions inForMaTion
SEPIC Converter: Output Diode Selection
To maximize efficiency, a fast switching diode with a low
forward drop and low reverse leakage is desirable. The
average forward current in normal operation is equal to
the output current, and the peak current is equal to:
It is recommended that the peak repetitive reverse voltage
rating V
margin (a 10V safety margin is usually sufficient).
The power dissipated by the diode is:
P
and the diode junction temperature is:
T
The R
for the device, plus the thermal resistance from the board,
to the ambient temperature in the enclosure. T
exceed the diode maximum junction temperature rating.
SEPIC Converter: Output and Input Capacitor Selection
The selections of the output and input capacitors of the
SEPIC converter are similar to those of the boost converter.
Please refer to the Boost Converter, Output Capacitor
Selection and Boost Converter, Input Capacitor Selection
sections.
SEPIC Converter: Selecting the DC Coupling Capacitor
The DC voltage rating of the DC coupling capacitor (C
as shown in Figure 1) should be larger than the maximum
input voltage:
V

I
D PEAK
J
D
CDC
(
= T
= I
θJA
> V
RRM
O(MAX)
A
used in this equation normally includes the R
+ P
)
=
IN(MAX)
is higher than V

 
D
1
• R
• V
+
c
2
D
θJA

 
•
I
O MAX
(
)
OUT
•
1
−
+ V
D
1
MAX
IN(MAX)
by a safety
J
must not
θJC
DC
,
C
the switch off-time, the current through C
approximately –I
rating of the coupling capacitor is determined by the fol-
lowing equation:
A low ESR and ESL, X5R or X7R ceramic capacitor works
well for C
INVERTING CONVERTER APPLICATIONS
The LT3757 can be configured as a dual-inductor invert-
ing topology, as shown in Figure 10. The V
ratio is:
in continuous conduction mode (CCM).
DC
I
V
RMS CDC
has nearly a rectangular current waveform. During
V
OUT
IN
V
(
IN
+
−
DC
Figure 10. A Simplified Inverting Converter
V
)
.
D
C
>
IN
= −
I
O MAX
(
O
− 1
LT3757
flows during the on-time. The RMS
D
SENSE
GATE
D
)
GND
•
L1
V
V
OUT
IN MIN
M1
(
+ –
R
C
SENSE
+
DC
V
)
D
D1 C
L2
OUT
DC
is I
OUT
+
3757 F09
IN
V
–
+
to V
OUT
, while
3757fb
IN