LTC1773 LINER [Linear Technology], LTC1773 Datasheet - Page 14

• Manufacturer Part Number: LTC1773
• Description: Synchronous Step-Down DC/DC Controller
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
LTC1773
For the selection of the external MOSFETs, the R
must be guaranteed at 2.5V since the LTC1773 has to
operate down to 2.7V. This requirement can be met by the
Si9801DY.
For the feedback resistors, choose R1 = 80.6k. R2 can then
be calculated from equation (2) to be:
14
U
INFORMATION
C
C
L1: CDRH5D28
R
U
IN
OUT
SENSE
: SANYO POSCAP 6TPA150M
0.1µF
33pF
80.6k
30k
: AVX TPSD227M006R0100
1%
: IRC LR1206-01-R033-F
200pF
V
IN
W
1
2
3
4
5
Figure 7. Single Lithium-Ion to 2.5V/2A Regulator
I
RUN/SS
SYNC/FCB
V
GND
TH
FB
LTC1773
100
95
90
85
80
75
70
SENSE
1
V
U
OUT
SW
V
Efficiency Curve for Figure 7
TG
BG
IN
169k
–
1%
= 2.5V
DS(ON)
10
9
8
7
6
OUTPUT CURRENT (mA)
10
Si9801DY
V
0.033Ω
R
IN
SENSE
100
= 3.3V
Figure 7 shows the complete circuit along with its effi-
ciency curve.
R
2
=
⎛
⎜
⎝
V
1000
0 8
OUT
2.5µH
.
L1
1773 F1b
5000
–
1 1 171
⎞
⎟
⎠
V
+
2.5V
R
2A
OUT
2.7V ≤ V
=
C
220µF
6.3V
OUT
+
IN
k use
≤ 4.2V
;
C
150µF
6.3V
1773 F07a
IN
169
k
1773fb