Datasheet LT3435 (Analog Devices)

LT3435 High Voltage 3A, 500kHz Step-Down Switching Regulator with 100µA Quiescent Current
U FEATURES DESCRIPTIO
■
Wide Input Range: 3.3V to 60V
The LT®3435 is a 500kHz monolithic buck switching ■
3A Peak Switch Current
regulator that accepts input voltages up to 60V. A high ■
Burst Mode® Operation: 100
µ
A Quiescent Current**
efficiency 3A, 0.1Ω switch is included on the die along with ■
Low Shutdown Current: IQ < 1
µ
A
all the necessary oscillator, control and logic circuitry. ■
Power Good Flag with Programmable Threshold
Current mode topology is used for fast transient response ■
Load Dump Protection to 60V
and good loop stability. ■ 500kHz Switching Frequency Innovative design techniques along with a new high volt- ■ Saturating Switch Design: 0.1Ω On-Resistance age process achieve high efficiency over a wide input ■ Peak Switch Current Maintained Over range. Efficiency is maintained over a wide output current Full Duty Cycle Range* range by employing Burst Mode operation at low currents, ■ 1.25V Feedback Reference Voltage utilizing the output to bias the internal circuitry, and by ■ Easily Synchronizable using a supply boost capacitor to fully saturate the power ■ Soft-Start Capability switch. Patented circuitry maintains peak switch current ■ Small 16-Pin Thermally Enhanced TSSOP Package
U
over the full duty cycle range.* Shutdown reduces input
APPLICATIO S
supply current to less than 1µA. External synchronization can be implemented by driving the SYNC pin with logic-level ■ High Voltage Power Conversion inputs. A single capacitor from the CSS pin to the output ■ 14V and 42V Automotive Systems provides a controlled output voltage ramp (soft-start). The ■ Industrial Power Systems device also has a power good flag with a programmable ■ Distributed Power Systems threshold and time-out and thermal shutdown protection. ■ Battery-Powered Systems The LT3435 is available in a 16-pin TSSOP package with an ■ USB Powered Systems exposed pad leadframe for low thermal resistance. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents including 6498466 **See Burst Mode Operation section for conditions.
U TYPICAL APPLICATIO Efficiency and Power Loss 14V to 3.3V Step-Down Converter with Supply Current vs Input Voltage vs Load Current 100
µ
A No Load Quiescent Current
150 100 10 V VIN = 12V OUT = 3.3V T 90 V A = 25°C OUT 125 VIN VIN BOOST 3.3V 80 4.7µF 0.33µF 15µH 2A VOUT = 5V 1 SHDN 4148 POWER LOSS (W) 100V SW µA) 70 100 EFFICIENCY CER LT3435 0.1µF 60 B360A V C C SS 75 50 VOUT = 3.3V 0.1 4700pF 470pF TYPICAL VBIAS 40 165k POWER LOSS EFFICIENCY (%) 10k 27pF 50 FB 1% + 100µF 30 CT 10V SUPPLY CURRENT ( 0.01 PGFB 1µF SYNC 20 TANT 100k 25 GND PG 1% 10 0 0 0.001 3435 TA01 0 10 20 30 40 50 60 0.0001 0.001 0.01 0.1 1 10 INPUT VOLTAGE (V) LOAD CURRENT (A) 3435 TA02 3435 TA03 3435fa 1