LT3439 Slew Rate Controlled Ultralow Noise1A Isolated DC/DC Transformer Driver FEATURES DESCRIPTIO n Reduced Conducted and Radiated EMI The LT 3439 is a push-pull DC/DC transformer driver that n Single Resistor Control of Output Switch Voltage reduces conducted and radiated electromagnetic interfer- and Current Slew Rates ence (EMI). Ultralow noise and EMI are achieved by n Cross Conduction Prevention Circuitry controlling the output switch voltage and current slew n Two 1A Current Limited Power Switches rates. Slew rates are user adjustable to optimize output n Low Minimum Supply Voltage: 2.8V noise versus efficiency. The LT3439 can reduce high n Low Shutdown Current: <20m A frequency harmonic content by as much as 40dB with only n 50% Duty Cycle a minor decrease in efficiency. n 20kHz to 250kHz Oscillator Frequency The LT3439 includes two 1A current limited power switches n Synchronizable to 300kHz to ensure start-up under heavy loads. It also includes an n Overcurrent and Overtemperature Protected oscillator that can be synchronized to an external clock for more accurate placement of switcher harmonics. Protec- U tion features include current limiting, undervoltage lock- APPLICATIO S out, thermal shutdown and cross conduction prevention n Low Noise Isolated Supplies circuitry. n Radio and Telecom Supplies The LT3439 is available in a thermally enhanced 16-pin n Distributed Supplies TSSOP with an exposed backside. n Medical Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. n Precision Instruments n Low Noise Filament Supplies TYPICAL APPLICATIO Low Noise 5V to 5V Push-Pull DC/DC Transformer 5V Output Noise OPTIONAL D1 V L1 33H V IN A B T1 OUT 5V 5V C IN 13 C1 C2 500mA 22F 47F 47F V 10V IN B 6.3V 6.3V 3 11 200m V/DIV SHDN COL A LT3439 14 5 SYNC COL B 6 C D2 T C : MURATA GRM235Y5V226Z10 IN 680pF 7 4 C1, C2: TDK C4532X5R0J476M R R T SL A D1, D2: MBR0520 16.9k GND PGND 20mV/DIV 34k L1: TDK SLF6028T-330MR69 T1: COILTRONICS 15835 10 1, 16 3439 TA01 5m s/DIV 3439 TA01b sn3439 3439fs 1 U ULT3439 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW V Voltage ............................................................. 20V IN ORDER PART PGND 1 16 PGND COL A, COL B Voltage............................................. 35V NUMBER NC 2 15 NC SHDN, SYNC Voltage .............................................. 20V COL A 3 14 COL B LT3439EFE Maximum Junction Temperature ......................... 150 C R 4 13 V SL IN Operating Junction Temperature Range SYNC 5 12 NC (Note 2) ............................................ 40 C to 125 C C 6 11 SHDN T Storage Temperature Range ................ 65 C to 150 C FE PART R 7 10 GND T MARKING Lead Temperature (Soldering, 10 sec)................. 300 C NC 8 9 NC FE PACKAGE 3439EFE 16-LEAD PLASTIC TSSOP T = 125 C, q = 40 C/ W JMAX JA NOTE: BACKSIDE OF PACKAGE CONNECTED TO GND Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. A V = 5V R = 16.9k C = 680pF R = 16.9k COL A, COL B, SHDN pins open, unless otherwise noted. IN T T SL SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply and Shutdown V Operating Range l 2.8 17.5 V IN V Minimum Input Voltage 2.55 2.7 V IN(MIN) I Supply Current 2.8V V 17.5V l 12 mA VIN IN I Supply Current in Shutdown Mode 2.8V V 17.5V, V = 0V 5 20 m A VIN(SHDN) IN SHDN V Shutdown Turn-On Threshold 2.8V V 17.5V l 1.3 1.4 V SHDN(ON) IN V Shutdown Turn-Off Threshold 2.8V V 17.5V l 1.20 1.26 V SHDN(OFF) IN I Shutdown Pin Current Hysteresis 2.8V V 17.5V, V = 1.4V l 10 20 40 m A SHDN IN SHDN Oscillator and Sync f Oscillator Frequency l 250 kHz MAX f Synchronization Frequency Range l 300 kHz SYNC V SYNC Pin Threshold l 1.4 2.25 V SYNC R SYNC Pin Input Resistance 40 kW SYNC Output Switches (COL A, COL B) DC Switch Duty Cycle l 50 % BV Output Switch Breakdown Voltage 2.8V V 17.5V l 35 50 V IN R Output Switch On Resistance I or I = 0.75A l 0.5 0.95 W ON COLA COLB I Switch Current Limit 1.2 1.4 1.65 A LIM(MAX) Slew Control V Output Voltage Slew Rising Edge Collector A or B 17 V/m s SLEWR V Output Voltage Slew Falling Edge Collector A or B 17 V/m s SLEWF I Output Current Slew Rising Edge Collector A or B 5 A/m s SLEWR I Output Current Slew Falling Edge Collector A or B 5 A/m s SLEWF Note 1: Absolute Maximum Ratings are those values beyond which the life Note 2: The LT3439E is guaranteed to meet performance specifications of a device may be impaired. from 0 C to 70 C. Specifications over the 40 C to 125 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. sn3439 3439fs 2 U WWW