ltc1709-7 Linear Technology Corporation, ltc1709-7 Datasheet - Page 27

• Manufacturer Part Number: ltc1709-7
• Description: 2-phase, 5-bit Vid, Current Mode, High Efficiency, Synchronous Step-down Switching Regulator
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
PACKAGE DESCRIPTIO
An interesting result of the 2-phase solution is that the V
which produces worst-case ripple current for the input
capacitor, V
duces zero input current ripple in the 2-phase design.
The output ripple current is reduced significantly when
compared to the single phase solution using the same
inductance value because the V
term from the stage that has its bottom MOSFET on
subtracts current from the (V
resulting from the stage which has its top MOSFET on. The
output ripple current is:
(0.005 – 0.009)
**
*
0.13 – 0.22
NOTE: DIMENSIONS ARE IN MILLIMETERS
DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.152mm (0.006") PER SIDE
DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.254mm (0.010") PER SIDE
OUT
= V
U
IN
(0.205 – 0.212)
/2, in the single phase design pro-
5.20 – 5.38**
(0.022 – 0.037)
0.55 – 0.95
U
IN
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
– V
OUT
OUT
W
/L discharge current
)/L charging current
U
0 – 8
Dimensions in inches (millimeters) unless otherwise noted.
36-Lead Plastic SSOP (0.209)
U
(LTC DWG # 05-08-1640)
(0.0256)
G Package
0.65
BSC
IN
36
1 2 3 4 5 6 7 8 9 10 11 12
(0.010 – 0.015)
35
0.25 – 0.38
where D is duty factor.
The input and output ripple frequency is increased by the
number of stages used, reducing the output capacity
requirements. When V
as illustrated in Figures 3 and 4, very low input and output
ripple currents result.
34
33
I
RIPPLE
32
31
30
(0.499 – 0.509)
29
12.67 – 12.93*
2
28
V
fL
OUT
27
26
IN
25
1 2
is approximately equal to 2(V
13
24
1 2
23
14 15 16 17 18
D
22 21 20 19
D
1
1
D
(0.002 – 0.008)
0.05 – 0.21
(0.068 – 0.078)
LTC1709-7
1.73 – 1.99
(0.301 – 0.311)
G36 SSOP 1098
7.65 – 7.90
27
OUT
)