LM34919BTLX National Semiconductor Corporation, LM34919BTLX Datasheet - Page 18

• Manufacturer Part Number: LM34919BTLX
• Description: Lm34919b Ultra Small 40v, 600 Ma Constant On-time Buck Switching Regulator
• Manufacturer: National Semiconductor Corporation

www.national.com
where Iout is the load current, V
age drop, and D is the on-time duty cycle. The power loss in
the inductor is approximately:
where R
is an approximation for the AC losses. If it is expected that the
L
is the inductor’s DC resistance, and the 1.1 factor
P
P
D1
L1
= Iout x V
= Iout
2
x R
F
F
is the diode’s forward volt-
L
x (1-D)
x 1.1
18
internal dissipation of the LM34919B will produce excessive
junction temperatures during normal operation, good use of
the PC board’s ground plane can help to dissipate heat. Ad-
ditionally the use of wide PC board traces, where possible,
can help conduct heat away from the IC. Judicious positioning
of the PC board within the end product, along with the use of
any available air flow (forced or natural convection) can help
reduce the junction temperatures.