SC2440
SC2440 is 2.5 MHz Dual Switching Regulator manufactured by SEMTECH.
Description
The SC2440 is an adjustable frequency dual currentmode switching regulator with 2A integrated switches. Its high frequency operation allows the use of small inductors and capacitors, resulting in very pact power supplies. The SC2440 is suitable for next generation XDSL modems requiring operating frequencies in excess of 1.5 MHz. The two channels operate at 180° out of phase for reduced input voltage ripples. Separate soft start/ shutdown pins allow independent control and output sequencing for latch-up prevention. The SC2440 can also be externally synchronized up to 2.5 MHz per channel. Current-mode PWM control allows fast transient response with simple loop pensation. Cycle-by-cycle current limiting and hiccup overload protection reduce power dissipation during overload.
Features u Up to 2.5 MHz/Channel Programmable Switching u u u u u u u u u u u u u u u u u
Frequency Fixed Frequency Current-mode Control Wide Input Voltage Range 2.8V to 20V Out of Phase Switching Reduces Ripple Cycle-by-cycle Current-limiting Independent Shutdown/soft-start Pins Independent Hiccup Overload Protection Independent Power-Good Indicators Two 2A Integrated Switches External Synchronization Thermal Shutdown Thermally Enhanced 16-pin TSSOP Package XDSL and Cable Modems Set-up Boxes Point of Load Applications CPE Equipment DSP Power Supplies Disk Drives
Applications
Typical Application Circuit
R6 100K FB1 PGOOD1 BOOST1 D3 C2 1N4148 0.1µ F L1 P1 C7 10p F SS1 22n F R9 ROSC C10 22n F C9 P2 R7 10p F C8 24.3K 220p F FB2 GND BOOST2 R8 PGOOD2 100K 1N4148 SW2 C4 0.1µ F 15K SS2 SYNC SW1 VIN 12V C15 IN 10µ F D2 UPS120 L2 4.4µ H D4 C3 10µ F R4 10K R3 40.2K OUT2 5V/2A 3.3µ H D1 UPS120 C1 10µ F R1 23.3K R2 10K
R5
C5
Efficiency vs Load Current
OUT1 3.3V/2A
15.4K C6 470p F
90 85 Efficiency (%) 80 75 70 65 60 55 50 0
VIN = 12V
VOUT2 = 5V
V OUT1 = 3.3V
L1: Sumida CR43 L2: F alco D04012
Load Current (A)
Figure 1. 1.3MHz 12V to 3.3V and 5V Step-down...
