SC2620 Datasheet, PDF (1/26 Pages) Semtech Corporation – Dual 2A, 30V Step-down Regulator with Programmable Frequency up to 1.4MHz

SC2620
Dual 2A, 30V Step-down Regulator with
Programmable Frequency up to 1.4MHz
POWER MANAGEMENT
Description
The SC2620 is a constant frequency dual current-mode
switching regulator with integrated 2.3A, 30V switches.
Its switching frequency can be programmed up to 1.4MHz
per channel. Due to the SC2620’s high frequency
operation, small inductors and ceramic capacitors can be
used, resulting in very compact power supplies. The two
channels of the SC2620 operate at 180° out of phase for
reduced input voltage ripples.
Separate soft start/enable pins allow independent control
of each channel. Channel 1 power good indicator can be
used for output start up sequencing to prevent latch-up.
Current-mode PWM control achieves fast transient
response with simple loop compensation. Cycle-by-cycle
current limiting and hiccup overload protection reduce
power dissipation during overload.
Features
‹ Wide Input Voltage Range 2.8V to 30V
‹ Up to 1.4MHz/Channel Programmable Switching
Frequency
‹ Current-mode Control
‹ Out of Phase Switching Reduces Ripple
‹ Cycle-by-cycle Current-limiting
‹ Independent Shutdown/soft-start Pins
‹ Independent Hiccup Overload Protection
‹ Channel 1 Power Good Indicator
‹ Two 2.3A Integrated Switches
‹ Thermal Shutdown
‹ Thermally Enhanced SO-16 Lead Free Package
‹ Fully WEEE and RoHS Compliant
Applications
‹ XDSL and Cable Modems
‹ Set-top Boxes
‹ Point of Load Applications
‹ CPE Equipment
‹ DSP Power Supplies
Typical Application Circuit
R5
C5
12. 7k _{C6 1.5nF}
C7 47pF
22nF _R9
46. 4 k
C10
22nF
C9
R7 ^{33pF C8}
10.5k _4.7nF
FB1
COMP1 BOOST1
SS1
SW1
ROSC
SC2620
PGOOD1 PVIN
SS2
VIN
COMP2
SW2
FB2
BOOST2
GND
D3
9V-16V VIN
C15
R10 10µF
10
C2 1N4148
0.1µF _L1
10µH
D1
UPS120
C1
22µF
R1
30. 1 k
R2
13k
OUT1
3.3V /2A
C16
0.1µF
D4
1N4148
D2
UPS120
L2
C4
0.1µF
6.8µH
OUT2
C3
22µF
R3 ^1.2V/2A
2.6 1 k
R4
13k
L1 & L2: Coiltr onics DR73
C1 & C3: Murata GRM21BR60J 226M
C15: Murata GRM32DR61E106K
V _IN = 1 2 V
CH1
CH2
CH3
4ms/div
CH1 : OUT1 Voltage, 2V/div
CH2 : OUT2 Voltage, 1V/div
CH3 : SS2 Voltage, 2V/div
Figure 1(a). 550kHz 9V-16V V_IN to 3.3V and 1.2V Step-
down Converter.
Figure 1(b). V_IN Start-up Transient (I_OUT1= 1.5A, I_OUT2=
0.8A). Channel 2 start is delayed until
Channel 1 reaches regulation.
Revision: December 20th, 2006
1
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