Datasheet LT1938 (Analog Devices) - 4

LT1938
TYPICAL PERFORMANCE ChARACTERISTICS (TA = 25°C unless otherwise noted) Efficiency (VOUT = 5.0V) Efficiency (VOUT = 3.3V) Efficiency
100 90 90 VIN = 7V VIN = 12V V 85 85 IN = 12V 90 80 80 VIN = 24V V V IN = 12V VIN = 24V IN = 24V 80 75 75 70 70 70 EFFICIENCY (%) EFFICIENCY (%) 65 EFFICIENCY (%) 65 60 60 60 VOUT = 3.3V L: NEC PLC-0745-4R7 55 L: NEC PLC-0745-4R7 55 L = 10µH f = 800kHz f = 800kHz LOAD = 1A 50 50 50 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 0 0.5 1 1.5 2 2.5 3 LOAD CURRENT (A) LOAD CURRENT (A) SWITCHING FREQUENCY (MHz) 1938 G01 1938 G02 1938 G03
Maximum Load Current Maximum Load Current Switch Current Limit
4.0 4.0 4.0 3.5 3.5 3.5 TYPICAL TYPICAL 3.0 3.0 3.0 MINIMUM MINIMUM 2.5 2.5 2.5 LOAD CURRENT (A) 2.0 LOAD CURRENT (A) 2.0 2.0 VOUT = 3.3V VOUT = 5V SWITCH CURRENT LIMIT (A) 1.5 TA = 25°C 1.5 TA = 25°C 1.5 L = 4.7µH L = 4.7µH f = 800kHz f = 800kHz 1.0 1.0 1.0 5 10 15 20 25 5 10 15 20 25 0 20 40 60 80 100 INPUT VOLTAGE (V) INPUT VOLTAGE (V) DUTY CYCLE (%) 1938 G04 1938 G05 1938 G06
Switch Current Limit Switch Voltage Drop Boost Pin Current
4.5 700 90 4.0 DUTY CYCLE = 10 % 600 80 3.0 70 500 60 2.5 DUTY CYCLE = 90 % 400 50 2.0 300 40 1.5 TAGE DROP (mV) 30 VOL 200 SWITCH CURRENT LIMIT (A) 1.0 BOOST PIN CURRENT (mA) 20 0.5 100 10 0 0 0 –50 –25 0 25 50 75 100 125 0 500 1000 1500 2000 2500 3000 3500 0 500 1000 1500 2000 2500 3000 3500 TEMPERATURE (°C) SWITCH CURRENT (mA) SWITCH CURRENT (mA) 1938 G07 1938 G08 1938 G09 1938fa 4 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL ChARACTERISTICS TYPICAL PERFORMANCE ChARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS