LT1578IS8 Linear Technology, LT1578IS8 Datasheet - Page 11

• Manufacturer Part Number: LT1578IS8
• Description: IC BUCK SYNC ADJ 1.5A 8SOIC
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LT1578IS8

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: Adj to 1.21V
• Current - Output: 1.5A
• Frequency - Switching: 200kHz
• Voltage - Input: 4 ~ 15 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

APPLICATIONS
3. Decide if the design can tolerate an “open” core geom-
4. Start shopping for an inductor (see representative
5. After making an initial choice, consider the secondary
V
f = Switching frequency, 200kHz
etry like a rod or barrel, with high magnetic field
radiation, or whether it needs a closed core like a toroid
to prevent EMI problems. One would not want an open
core next to a magnetic storage media, for instance!
This is a tough decision because the rods or barrels are
temptingly cheap and small and there are no helpful
guidelines to calculate when the magnetic field radia-
tion will be a problem.
surface mount units in Table 1) which meets the
requirements of core shape, peak current (to avoid
saturation), average current (to limit heating), and fault
current (if the inductor gets too hot, wire insulation will
melt and cause turn-to-turn shorts). Keep in mind that
all good things like high efficiency, low profile, and high
temperature operation will increase cost, sometimes
dramatically. Get a quote on the cheapest unit first to
calibrate yourself on price, then ask for what you really
want.
things like output voltage ripple, second sourcing, etc.
Use the experts in the Linear Technology’s applica-
tions department if you feel uncertain about the final
choice. They have experience with a wide range of
inductor types and can tell you about the latest devel-
opments in low profile, surface mounting, etc.
IN
I
PEAK
= Maximum input voltage
I
OUT
U
V
OUT
2
INFORMATION
U
f L V
V
IN
V
IN
OUT
W
U
Table 1
VENDOR/
PART NO.
Coiltronics
CTX15-2
CTX33-2
CTX68-4
CTX15-1P
CTX33-2P
CTX68-4P
Sumida
CDRH74-150
CDH115-330
CDRH125-680
CDH74-330
Coilcraft
DO3308P-153
DO3316P-333
DO3316P-683
Pulse
PE-53602
PE-53604
PE-53632
PE-53633
Gowanda
SMP3316-152K
SMP3316-332K
SMP3316-682K
Tor = Toroid
SC = Semi-closed geometry
Fer = Ferrite core material
52 = Type 52 powdered iron core material
KM = Kool M
VALUE
( H)
15
33
68
15
33
68
15
33
68
33
15
33
68
35
73
22
40
15
33
68
(Amps) TYPE TANCE( )
1.47
1.68
1.45
1.7
1.4
1.2
1.4
1.3
1.1
1.5
1.4
1.4
1.3
2.7
2.7
3.5
2.3
1.7
DC
2
2
LT1578/LT1578-2.5
CORE
Tor
Tor
Tor
Tor
Tor
Tor
Tor
Tor
Tor
Tor
SC
SC
SC
SC
SC
SC
SC
SC
SC
SC
SERIES
RESIS-
0.059
0.106
0.158
0.087
0.126
0.238
0.081
0.082
0.166
0.290
0.063
0.085
0.041
0.092
0.178
0.12
0.17
0.12
0.18
0.1
MATER- HEIGHT
CORE
KM
KM
KM
IAL
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
Fer
52
52
52
11
(mm)
5.21
5.21
6.0
6.0
6.4
4.2
6.0
6.4
4.5
5.2
5.2
9.1
9.1
9.1
10
6
3
6
6
6