LTC1871IMS Linear Technology, LTC1871IMS Datasheet - Page 30

• Manufacturer Part Number: LTC1871IMS
• Description: IC MULTI CONFIG SYNC ADJ 10MSOP
• Manufacturer: Linear Technology
• Type: Step-Up (Boost), Flyback, Sepicr

Specifications of LTC1871IMS

• Internal Switch(s): No
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 1.23 ~ 72 V
• Current - Output: 50mA
• Frequency - Switching: 50kHz ~ 1MHz
• Voltage - Input: 2.5 ~ 36 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

LTC1871
APPLICATIONS INFORMATION
9. The DC coupling capacitor in a SEPIC converter is cho-
30
sen based on its RMS current requirement and must be
rated for a minimum voltage of V
voltage. Start with the minimum value which satisfi es
the RMS current requirement and then check the ripple
voltage to ensure that it doesn’t exceed the DC rating.
I
RMS(CI)
C
47pF
C2
I
R
33k
O(MAX)
= 1.5A •
C
105k
C
6.8nF
1%
C1
R2
C
C
D1:
12.1k
IN
DC
, C
1%
, C
R1
•
OUT1
OUT2
V
12V + 0.5V
V
: KEMET T495X476K020AS
: TAIYO YUDEN TMK432BJ106MM
IN(MIN)
O
INTERNATIONAL RECTIFIER 30BQ040
R
80.6k
1%
+ V
T
5V
Figure 18a. 4.5V to 15V Input, 12V/2A Output SEPIC Converter
D
1
2
3
4
5
R3
1M
IN
RUN
I
FB
FREQ
MODE/SYNC
TH
plus the AC ripple
Figure 18b. SEPIC Effi ciency vs Output Current
= 2.4A
LTC1871
100
95
90
85
80
75
70
65
60
55
50
45
0.001
INTV
SENSE
GATE
GND
V
V
CC
IN
IN
= 4.5V
0.01
10
9
8
7
6
OUTPUT CURRENT (A)
V
IN
V
L1, L2: BH ELECTRONICS BH510-1007 (*COUPLED INDUCTORS)
M1:
= 15V
IN
= 12V
C
4.7μF
X5R
0.1
VCC
INTERNATIONAL RECTIFIER IRF7811W
For this design a single 10μF , low ESR (X5R) Taiyo Yuden
ceramic capacitor (TMK432BJ106MM) is adequate.
+
V
MODE = INTV
O
= 12V
1
C
47μF
IN
L1*
1871 F18b
•
M1
CC
10μF
10
X5R
C
25V
DC
•
L2*
D1
+
C
47μF
20V
×2
OUT1
1871 F018a
C
10μF
25V
X5R
×2
OUT2
GND
V
4.5V to 15V
V
12V
1.5A
(2A PEAK)
IN
OUT
1871fe