LM3488MM National Semiconductor, LM3488MM Datasheet - Page 19
![IC, N-CH CONTROLLER, MSOP-8](/photos/18/97/189768/3778330_sml.jpg)
LM3488MM
Manufacturer Part Number
LM3488MM
Description
IC, N-CH CONTROLLER, MSOP-8
Manufacturer
National Semiconductor
Datasheet
1.LM3488MM.pdf
(24 pages)
Specifications of LM3488MM
Primary Input Voltage
40V
No. Of Outputs
1
Output Current
1A
No. Of Pins
8
Operating Temperature Range
-40°C To +125°C
Termination Type
SMD
Input Voltage Primary Min
2.95V
Output Voltage Min
1.26V
Rohs Compliant
No
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM3488MM
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
LM3488MM/NOPB
Manufacturer:
TI
Quantity:
15 540
Part Number:
LM3488MMX
Manufacturer:
NS/国半
Quantity:
20 000
Company:
Part Number:
LM3488MMX/NOPB
Manufacturer:
ATMEL
Quantity:
3 410
In the above equation, V
FET, Q, and V
POWER MOSFET SELECTION
As in boost converter, the parameters governing the selection
of the MOSFET are the minimum threshold voltage, V
(MIN)
reverse transfer capacitance, C
to source voltage, V
SEPIC is given by:
The selected MOSFET should satisfy the condition:
The peak switch current is given by:
The rms current through the switch is given by:
POWER DIODE SELECTION
The Power diode must be selected to handle the peak current
and the peak reverse voltage. In a SEPIC, the diode peak
current is the same as the switch peak current. The off-state
voltage or peak reverse voltage of the diode is V
Similar to the boost converter, the average diode current is
equal to the output current. Schottky diodes are recommend-
ed.
SELECTION OF INDUCTORS L1 AND L2
Proper selection of the inductors L1 and L2 to maintain con-
stant current mode requires calculations of the following pa-
rameters.
Average current in the inductors:
, the on-resistance, R
V
DIODE
SW(PEAK)
V
is the forward voltage drop of the diode.
DS(MAX)
DS(MAX)
Q
= V
DS(ON)
is the on-state voltage of the MOS-
IN
. The peak switch voltage in a
> V
+ V
, the total gate charge, Q
RSS
SW(PEAK)
OUT
, and the maximum drain
+ V
DIODE
FIGURE 14. Typical SEPIC Converter
IN
+ V
g
, the
OUT
TH
.
19
Peak to peak ripple current, to calculate core loss if neces-
sary:
maintains the condition I
mode.
Peak current in the inductor, to ensure the inductor does not
saturate:
I
L2AVE
L
> Δi
= I
L
/2 to ensure constant current
OUT
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