LTC1628IG-SYNC#PBF Linear Technology, LTC1628IG-SYNC#PBF Datasheet - Page 9

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

Specifications of LTC1628IG-SYNC#PBF

• 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: -

FU CTIO AL DIAGRA
OPERATIO
Main Control Loop
The LTC1628-SYNC uses a constant frequency, current
mode step-down architecture with the two controller
channels operating 180 degrees out of phase. During
normal operation, each top MOSFET is turned on when the
clock for that channel sets the RS latch, and turned off
when the main current comparator, I
R6
R5
V
F
IN
+
IN
R
V
5V
U
C
SEC
LP
LP
PLLFLTR
PGOOD
3.3V
EXTV
INTV
PLLIN
SGND
FCB
V
IN
50k
OUT
CC
0.18µA
CC
3V
U
OSCILLATOR
4.7V
PHASE DET
+
–
4.5V
0.8V
U
–
+
(Refer to Functional Diagram)
–
+
+
–
CLK1
CLK2
INTERNAL
–
–
–
–
+
+
+
+
SUPPLY
V
LDO
REG
5V
REF
0.86V
0.74V
0.86V
0.74V
BINH
FCB
V
V
OSENSE1
OSENSE2
W
1
DUPLICATE FOR SECOND
CONTROLLER CHANNEL
, resets the RS latch.
1.2µA
6V
4(V
0.86V
FB
SLOPE
COMP
)
I1
S
R
+
–
0.55V
Q
Q
–
Figure 2
DROP
OUT
DET
45k
–
+
+
4(V
SHDN
+
RST
FB
B
The peak inductor current at which I
is controlled by the voltage on the I
output of each error amplifier EA. The V
the voltage feedback signal, which is compared to the
internal reference voltage by the EA. When the load current
increases, it causes a slight decrease in V
the 0.8V reference, which in turn causes the I
3mV
)
BOT
TOP ON
–
SHDN
FCB
START
45k
SOFT
RUN
–
+
OV
2.4V
EA
I2
SWITCH
–
+
+
–
LOGIC
V
FB
0.80V
0.86V
TOP
BOT
INTV
CC
INTV
30k
30k
CC
V
SENSE
SENSE
RUN/SS
BOOST
PGND
OSENSE
SW
I
TG
BG
TH
+
–
LTC1628-SYNC
INTV
CC
R1
D
C
C
C
B
D
R2
C2
SS
B
C
SEC
C
1
TH
V
resets the RS latch
OSENSE
IN
R
pin, which is the
C
OSENSE
D
R
SENSE
1
+
TH
pin receives
voltage to
relative to
C
C
IN
SEC
1628syncfa
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