Datasheet

FB
VIN
SW
RTN
BST
SM72485
8
6
5
3
4
1
2
7
SHUTDOWN
VCC
RCL
R
T
/SD
12V - 90V
Input
309k
C1
1.0 PF
R
T
R
CL
316k
R
FB1
1.0k
R
FB2
3.01k
R3
3.3
GND
C2
22 PF
V
OUT
10.0V
L1
220 PH
C3
0.47 PF
C4
0.01 PF
D1
C5
0.1 PF
SM72485
SNVS697D –JANUARY 2011–REVISED APRIL 2013 www.ti.com
If the internal dissipation of the SM72485 produces excessive junction temperatures during normal operation,
good use of the PC board’s ground plane can help considerably to dissipate heat. The exposed pad on the
bottom of the WSON package can be soldered to a ground plane on the PC board, and that plane should extend
out from beneath the IC to help dissipate the heat. Additionally, the use of wide PC board traces, where possible,
can also help conduct heat away from the IC. Judicious positioning of the PC board within the end product, along
with use of any available air flow (forced or natural convection) can help reduce the junction temperatures.
Figure 12. SM72485 Example Circuit
Table 1. Bill of Materials
Item Description Part Number Value
C1 Ceramic Capacitor TDK C4532X7R2A105M 1 µF, 100V
C2 Ceramic Capacitor TDK C4532X7R1E226M 22 µF, 25V
C3 Ceramic Capacitor Kemet C1206C474K5RAC 0.47 µF, 50V
C4 Ceramic Capacitor Kemet C1206C103K5RAC 0.01 µF, 50V
C5 Ceramic Capacitor TDK C3216X7R2A104M 0.1 µF, 100V
D1 Schottky Power Diode Diodes Inc. DFLS1100 100V, 1A
L1 Power Inductor COILTRONICS DR125-221-R, or 220 µH
TDK SLF10145T-221MR65
R
FB2
Resistor Vishay CRCW12063011F 3.01 kΩ
R
FB1
Resistor Vishay CRCW12061001F 1.0 kΩ
R3 Resistor Vishay CRCW12063R30F 3.3 Ω
R
T
Resistor Vishay CRCW12063093F 309 kΩ
R
CL
Resistor Vishay CRCW12063163F 316 kΩ
U1 Switching Regulator Texas Instruments SM72485
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