LTC1628IG-SYNC#TRPBF Linear Technology, LTC1628IG-SYNC#TRPBF Datasheet - Page 26

• Manufacturer Part Number: LTC1628IG-SYNC#TRPBF
• Description: IC SW REG STEP-DOWN 28-SSOP
• Manufacturer: Linear Technology
• Type: Step-Down (Buck)r

Specifications of LTC1628IG-SYNC#TRPBF

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: Adj to 0.8V
• Current - Output: 3A
• Frequency - Switching: 140kHz ~ 310kHz
• Voltage - Input: 3.5 ~ 30 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

APPLICATIO S I FOR ATIO
LTC1628-SYNC
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
LTC1628-SYNC. These items are also illustrated graphi-
cally in the layout diagram of Figure 10. The Figure 11
illustrates the current waveforms present in the various
branches of the 2-phase synchronous regulators operat-
ing in the continuous mode. Check the following in your
layout:
1. Are the top N-channel MOSFETs M1 and M3 located
within 1cm of each other with a common drain connection
at C
two channels as it can cause a large resonant loop.
26
IN
? Do not attempt to split the input decoupling for the
R1
R3
R2
R4
U
INTV
3.3V
CC
U
f
Figure 10. LTC1628-SYNC Recommended Printed Circuit Layout Diagram
IN
10
11
12
13
14
1
2
3
4
5
6
7
8
9
RUN/SS1
SENSE1
SENSE1
V
PLLFLTR
PLLIN
FCB
I
SGND
3.3V
I
V
SENSE2
SENSE2
TH1
TH2
OSENSE1
OSENSE2
OUT
W
LTC1628-SYNC
+
–
–
+
RUN/SS2
BOOST1
BOOST2
EXTV
PGOOD
INTV
PGND
SW1
SW2
BG1
BG2
TG1
TG2
V
CC
CC
IN
U
28
27
26
25
24
23
22
21
20
19
18
17
16
15
2. Are the signal and power grounds kept separate? The
combined LTC1628-SYNC signal ground pin and the
ground return of C
C
MOSFET, Schottky diode and the C
have short leads and PC trace lengths. The output capaci-
tor (–) terminals should be connected as close as possible
to the (–) terminals of the input capacitor by placing the
capacitors next to each other and away from the Schottky
loop described above.
3. Do the LTC1628-SYNC V
connect to the (+) terminals of C
must be connected between the (+) terminal of C
OUT
R
PGOOD
PU
C
C
(–) terminals. The path formed by the top N-channel
C
B1
B2
INTVCC
V
(<7V)
PULL-UP
C
VIN
V
R
IN
M1
IN
M3
INTVCC
M2
M4
L1
C
L2
IN
must return to the combined
OSENSE
R
R
OUT
SENSE
SENSE
C
C
OUT1
OUT2
pins resistive dividers
D1
D2
? The resistive divider
1628 F10
IN
capacitor should
V
GND
V
OUT1
OUT2
OUT
1628syncfa
and