POWER LOSS (W) LTC3546 Dual Synchronous, 3A/1A or 2A/2A Configurable Step-Down DC/DC Regulator FEATURES DESCRIPTION n V Range: 2.3V to 5.5V The LTC 3546 is a dual, constant-frequency, synchronous IN n V Range: 0.6V to 5V step down DC/DC converter for medium power applications. OUT n Programmable Frequency Operation 2.25MHz, or The design consists of 2A and 1A primary output switches. Adjustable Between 0.75MHz to 4MHz In addition to the 2A/1A capability, a 1A dependant output n Low R Internal Switches switch can be externally connected to either of the primary DS(ON) n High Efficiency: Up to 96% outputs to produce 3A/1A dual regulator or 2A/2A dual n No Schottky Diodes Required regulator configurations. n Short-Circuit Protected Supply operation is from 2.3V to 5.5V. The switching fre- n Current Mode Operation for Excellent Line and Load quency can be set to 2.25MHz, adjustable from 0.75MHz Transient Response to 4MHz, or synchronized to an external clock. Each n Low Ripple Burst Mode Operation (30mV ), P-P output is adjustable from 0.6V to 5V and has output I = 160A Q tracking on power-up. Internal synchronous low R DS(ON) n Ultralow Shutdown Current: I < 1A Q power switches provide high efficiency without external n Low Dropout Operation: 100% Duty Cycle Schottky diodes. n Power Good Output For Each Channel n User-selectable modes (Burst Mode operation, pulse Externally or Internally Programmable Burst Level n skipping and forced continuous) allow a trade-off between External or Internal Soft-Start or Supply Tracking n ripple noise and power efficiency. Burst Mode operation Available in Thermally Enhanced 28-Lead provides high efficiency at light loads. Pulse-skipping (4mm 5mm) QFN and TSSOP Packages mode provides low ripple noise at light loads. The device is capable of low dropout configurations and APPLICATIONS both channels can operate at 100% duty cycle. In shut- n Netbooks/Ultra-Mobile PCs down, the device draws <1A. n PC Cards All registered trademarks and trademarks are the property of their respective owners. Protected n Wireless and DSL Modems by U.S. Patents, including 5481178, 6611131, 6304066, 6498466, 6580258. n Point of Load DC/DC Conversion TYPICAL APPLICATION V IN V Efficiency (Burst Mode Operation) C OUT2 3.6V TO IN V V V V IN1 CCA CCD IN2 5.5V 22F 100 100 SYNC/MODE SW1D CONNECTED TO SW2 PGOOD2 PGOOD1 V = 3.6V 0.56H 1.22H IN V V OUT2 OUT1 V = 2.5V 95 OUT 10 SW2A SW1 2.5V, 3A 1.2V, 1A SW2B 100pF 100pF 90 1 EFFICIENCY SW1D V RUN2 LTC3546 RUN1 V IN IN 68F 22F 85 0.1 V V FB2 FB1 95.3k 30.1k V 30.1k BMC2 BMC1 IN 30.1k 80 0.01 V TRACK/SS2 TRACK/SS1 IN POWER LOSS PHASE FREQ 75 0.001 I I TH2 TH1 13k 13k PGND2 GNDA PGND1 10pF 10pF 70 0.0001 1000pF 1000pF 0.001 0.01 0.1 1 10 LOAD CURRENT (A) 3546 TA01a 3546 TA01b EXPOSED PAD 3546fd 1 For more information www.linear.com/3546 EFFICIENCY (%)LTC3546 ABSOLUTE MAXIMUM RATINGS (Note 1) V , V , V , V , V Voltages ......... 0.3V to 6V Maximum Difference Between Any of IN1 IN1D IN2 CCA CCD SYNC/MODE, SW1, SW1D, SW2A, SW2B, V , V , V , V , V ..................................0.3V IN1 IN1D IN2 CCA CCD RUN1, RUN2, V , V , PHASE, FREQ, PGOOD1, PGOOD2 Voltage .......................... 0.3V to 6V FB1 FB2 I , I , TRACK/SS1, TRACK/SS2, BMC1, Operating Junction Temperature Range TH1 TH2 BMC2 Voltages ................ 0.3V to (V or V ) + 0.3V (Notes 2, 6, 7) ........................................ 40C to 125C IN1 IN2 Storage Temperature Range ................... 65C to 125C PIN CONFIGURATION TOP VIEW TOP VIEW 1 28 GNDA V CCA 2 FREQ SYNC/MODE 27 PGOOD2 3 26 PGOOD1 28 27 26 25 24 23 BMC2 4 25 BMC1 BMC2 1 22 BMC1 TRACK/SS2 5 24 TRACK/SS1 TRACK/SS2 2 21 TRACK/SS1 6 23 V V FB1 FB2 V 3 20 V FB2 FB1 7 22 I I TH2 TH1 29 I 4 19 I TH2 TH1 29 8 PHASE V 21 CCD V 5 18 PHASE CCD RUN2 9 20 RUN1 6 17 RUN2 RUN1 V 10 19 PGND2 IN2 V 7 16 PGND2 IN2 V 11 18 PGND1 IN1 V 8 15 PGND1 IN1 12 17 PGND1D V IN1D 9 10 11 12 13 14 13 16 SW1 SW2A 14 SW1D SW2B 15 UFD PACKAGE FE PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN 28-LEAD PLASTIC TSSOP T = 125C, = 34C/W JMAX JA T = 125C, = 25C/W JMAX JA EXPOSED PAD (PIN 29) IS GNDD EXPOSED PAD (PIN 29) IS GNDD MUST BE SOLDERED TO PCB 3546fd 2 For more information www.linear.com/3546 V PGOOD2 IN1D SW2A SYNC/MODE SW2B V CCA SW1D GNDA SW1 FREQ PGND1D PGOOD1