SC1485ITSTRT Semtech, SC1485ITSTRT Datasheet - Page 17

• Manufacturer Part Number: SC1485ITSTRT
• Description: IC PWM BUCK CTRLR DUAL 28TSSOP
• Manufacturer: Semtech
• Type: Step-Down (Buck)r

Specifications of SC1485ITSTRT

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.5 ~ 25 V
• Voltage - Input: 1.8 ~ 25 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Power - Output: -
• Frequency - Switching: -
• Other names: SC1485ITSTR

The layout can be considered in two parts, the control section referenced to VSSA1/2 and the power section.
Looking at the control section first, locate all components referenced to VSSA1/2 on the schematic and place
these components at the chip. Connect VSSA1 and VSSA2 using either a wide (>0.020”) trace. Very little current
flows in the chip ground therefore large areas of copper are not needed.
POWER MANAGEMENT
2005 Semtech Corp.
PGOOD
PGOOD
Figure 9: Components Connected to VSSA1 and VSSA2
NOT RECOMMENDED FOR NEW DESIGN
VBAT
VBAT
R1
0402
C4
1nF
0402
R7
1M
0402
C18
1nF
0402
C7
0402
C15
56p
0402
VOUT
VOUT1
VOUT2
VOUT
R4
0402
R3
0402
R9
20k0
0402
R13
20k0
0402
R2
10R
0402
R8
10R
0402
5VSUS
5VSUS
17
C9
1uF
0603
C19
1uF
0603
VSSA1
VSSA2
22
23
24
25
26
27
28
10
11
12
13
14
8
9
U1
EN/PSV1
TON1
VOUT1
VCCA1
FB1
PGD1
VSSA1
EN/PSV2
TON2
VOUT2
VCCA2
FB2
PGD2
VSSA2
SC1485
PGND1
PGND2
VDDP1
VDDP2
ILIM1
ILIM2
BST1
BST2
DH1
DH2
DL1
DL2
LX1
LX2
7
6
5
4
3
2
1
21
20
19
18
17
16
15
5VSUS
5VSUS
C10
1uF
0603
C20
1uF
0603
SC1485
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