sc192imltr Semtech Corporation, sc192imltr Datasheet - Page 12

• Manufacturer Part Number: sc192imltr
• Description: Sc192 Synchronous Buck Converter With Integrated Power Devices
• Manufacturer: Semtech Corporation

The worst case RMS ripple current occurs at a duty cycle
of 0.5 and its value at that point is
Ceramic capacitors are recommended for input capaci-
tors because of their low ESR and high ripple current
capabilities. In addition, it is advised that the input ca-
pacitor be placed as close to the input pin of the IC as
possible.
Layout Considerations
PCB layout is of utmost importance because the switch-
ing frequency is 750kHz with peak currents over 1A. A
careful layout will avoid potential stability and EMI prob-
lems. Traces should be as wide and as short as possible.
Keep the input capacitor as close to the package as pos-
sible. This will help minimize large loop areas. Keep the
power ground and analog ground separated and tie the
two together at one common point. Notice the top cop-
per Gerber plot (see Page 8), pin 3 and pin 10 are tied
together under the package. Be aware of the high cur-
rent paths and avoid tying signal grounds to the high power
grounds where the signal paths might experience large
fluctuations in voltages as high currents pass though
copper traces.
© 2007 Semtech Corp.
POWER MANAGEMENT
Applications Information Cont.
I
RMS
=
V
OUT
•
V
IN
-
V
OUT
I
•
OUT
2
I
V
OUT
IN
.
12
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
100
100
0.10
0.08
0.06
0.04
0.02
0.00
1
95
90
85
80
75
70
65
60
95
90
85
80
1
1
2.7
20
10
10
3.0
40
Line Regulation At Iout = 300mA
30
30
60
3.3
Load Current (mA)
Load Regulation at Vin = 3.6V
Load Current (mA)
Input Voltage (Volts)
Efficiency at Vin = 3.6V
Efficiency at Vin = 5V
50
50
Ouput Current (mA)
80
3.6
70
70
100
3.9
90
90
200
4.2
200 400 600
200
300
4.5
400
400
4.8
PRELIMINARY
500
600
www.semtech.com
SC192
600
Vo = 2.5V
Vo = 1.8V
Vo = 3.3V
Vo = 1.8V
Vo = 1.8V
Vo = 2.5V