LTC1735CF Linear Technology, LTC1735CF Datasheet - Page 23

• Manufacturer Part Number: LTC1735CF
• Description: IC SW REG SYNC STEP-DWN 20-TSSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1735CF

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.8 ~ 6 V
• Current - Output: 3A
• Frequency - Switching: 300kHz
• Voltage - Input: 4 ~ 30 V
• Operating Temperature: 0°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

APPLICATIO S I FOR ATIO
voltage cannot exceed 0.082V. At V
maximum output voltage change controlled by the I
would be:
With the optimum resistor values at the I
voltage will swing from 1.55V at minimum load to 1.44V
at full load. At this output voltage, active voltage position-
ing provides an additional 56mV to the allowable tran-
sient voltage on the output capacitors, a 68% improve-
ment over the 82mV allowed without active voltage
positioning.
The next step is to calculate the scale factor for V
I
TH
100pF
0.1 F
47pF
C5
C2
C4
pin voltage. The V
V
100k
27k
R1
R2
OSENSE
100pF
39pF
1000pF
C1
C3
C6
Input Offset V
0 03
1
2
3
4
5
6
7
8
U
.
0 8
C
RUN/SS
I
FCB
SGND
V
SENSE
SENSE
TH
.
OSC
OSENSE
ITH
V
V
V
REF
LTC1735
• .
–
+
680k
100k
scale factor reflects the I
U
R3
R4
1 5
U1
Figure 8. CPU-Core-Voltage Regulator with Active Voltage Positioning
•
EXTV
BOOST
INTV
PGND
OUT
SW
V
BG
TG
CC
CC
IN
56
16
15
14
13
12
11
10
9
W
mV
5V (OPTIONAL)
TH
OUT
pin, the output
C9
1 F
D1
CMDSH-3
= 1.5V, the
U
+
C8
0.22 F
C7
0.1 F
ITH
TH
TH
C10
4.7 F
10V
, the
pin
pin
M1
FDS6680A
MBRS340
M2, M3
FDS6680A
2
voltage required for a given load current. V
peak sense resistor voltage, which represents the DC
output current plus one half of the peak-to-peak inductor
current. The no load to full load V
2.4V, which controls the sense resistor voltage from 0V to
the V
scale factor with a 0.003 sense resistor is:
V
V
ITH
ITH
V
D2
ITH
at any load current is:
Scale Factor
SENSE(MAX)
C9, C19: TAIYO YUDEN JMK107BJ105
C10: KEMET T494A475M010AS
C12 TO C14: TAIYO YUDEN GMK325F106
C15 TO C18: PANASONIC EEFUE0G181R
D1: CENTRAL SEMI CMDSH-3
D2: MOTOROLA MBRS340
L1: PANASONIC ETQP6F1R0SA
M1 TO M3: FAIRCHILD FDS6680A
R5: IRC LRF2512-01-R003-J
U1: LINEAR TECHNOLOGY LTC1735CS
1 H
L1
V
I
ITH
OUTDC
Offset
0.003
R5
voltage of 75mV. The calculated V
( .
V
2 4
ITH
2
I
L
V
Range Sense
1735 F08
– .
C11
330pF
11.5k
•
0 075
10k
0 3
.
V
R6
R7
ITH
V
ITH
•
V
+
) • .
V
Scale Factor
SENSE MAX
range is from 0.3V to
0 003
C15 TO
C18
180 F
4V
LTC1735
(
C12 TO C14
10 F
35V
Re
ITH
sistor Value
controls the
)
0 084
C19
1 F
.
23
V
7.5V TO
24V
GND
V
1.5V
15A
GND
V A
IN
OUT
1735fc
/
ITH