Datasheet LTC3838 (Analog Devices) - 7
| Manufacturer | Analog Devices |
| Description | Dual, Fast, Accurate Step- Down DC/DC Controller with Differential Output Sensing |
| Pages / Page | 54 / 7 — Typical perForMance characTerisTics. Soft Start-Up Into. Regular Soft … |
| File Format / Size | PDF / 746 Kb |
| Document Language | English |
Typical perForMance characTerisTics. Soft Start-Up Into. Regular Soft Start-Up. Pre-Biased Output. Output Tracking
Model Line for this Datasheet
Text Version of Document
LTC3838
Typical perForMance characTerisTics Soft Start-Up Into Regular Soft Start-Up Pre-Biased Output Output Tracking
RUN1 RUN1 5V/DIV 5V/DIV TRACK/SS1 200mV/DIV TRACK/SS1 200mV/DIV VOUT 500mV/DIV V TRACK/SS1 OUT V 500mV/DIV OUT 200mV/DIV 500mV/DIV 1ms/DIV 3838 G09 CSS = 10nF 1ms/DIV 3838 G10 CSS = 10nF 10ms/DIV 3838 G11 VIN = 12V VIN = 12V VIN = 12V VOUT = 1.2V VOUT = 1.2V VOUT = 1.2V FORCED CONTINUOUS MODE FORCED CONTINUOUS MODE VOUT PRE-BIASED TO 0.75V FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND
Overcurrent Protection Short-Circuit Protection Overvoltage Protection
SHORT- CIRCUIT IL IL TRIGGER 10A/DIV 5A/DIV V OVERVOLTAGE CREATED BY APPLYING FULL CURRENT LIMIT OUT V A CHARGED CAPACITOR TO V 1V/DIV OUT OUT WHEN V 100mV/DIV OUT HIGHER CURRENT LIMIT STARTS TO FOLD BACK AS THAN HALF OF REGULATED VOUT DROPS BELOW HALF OF REGULATED AC-COUPLED I C V L OUT OUT 10A/DIV RECHARGE BG1 100mV/DIV 5V/DIV AC-COUPLED 5ms/DIV 3838 G12 VIN = 12V 500µs/DIV 3838 G13 VIN = 12V 20µs/DIV 3838 G14 VIN = 12V VOUT = 1.2V VOUT = 1.2V VOUT = 1.2V BG STAYS ON UNTIL FORCED CONTINUOUS MODE ILOAD = 0A FORCED CONTINUOUS VOUT IS PULLED CURRENT LIMIT = 17A FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND MODE BELOW OVERVOLTAGE OVERLOAD = 7.5A TO 17.5A ILOAD = 0A THRESHOLD FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND
Phase Relationship: Phase Relationship: Phase Relationship: PHASMD = Ground PHASMD = Float PHASMD = INTVCC
PLLIN PLLIN PLLIN 5V/DIV 5V/DIV 5V/DIV SW1 SW1 SW1 0° 10V/DIV 0° 10V/DIV 0° 10V/DIV SW2 SW2 SW2 10V/DIV 180° 10V/DIV 180° 10V/DIV 240° CLKOUT CLKOUT CLKOUT 60° 5V/DIV 5V/DIV 90° 5V/DIV 120° 500ns/DIV 3838 G15 500ns/DIV 3838 G15 500ns/DIV 3838 G17 FIGURE 19 CIRCUIT FIGURE 19 CIRCUIT FIGURE 19 CIRCUIT VIN = 12V VIN = 12V VIN = 12V VOUT1 = 5V, VOUT2 = 3.3V VOUT1 = 5V, VOUT2 = 3.3V VOUT1 = 5V, VOUT2 = 3.3V LOAD = 0A LOAD = 0A LOAD = 0A MODE/PLLIN = 333kHz EXTERNAL CLOCK MODE/PLLIN = 333kHz EXTERNAL CLOCK MODE/PLLIN = 333kHz EXTERNAL CLOCK 3838fb For more information www.linear.com/LTC3838 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts
Typical perForMance characTerisTics Soft Start-Up Into Regular Soft Start-Up Pre-Biased Output Output Tracking
RUN1 RUN1 5V/DIV 5V/DIV TRACK/SS1 200mV/DIV TRACK/SS1 200mV/DIV VOUT 500mV/DIV V TRACK/SS1 OUT V 500mV/DIV OUT 200mV/DIV 500mV/DIV 1ms/DIV 3838 G09 CSS = 10nF 1ms/DIV 3838 G10 CSS = 10nF 10ms/DIV 3838 G11 VIN = 12V VIN = 12V VIN = 12V VOUT = 1.2V VOUT = 1.2V VOUT = 1.2V FORCED CONTINUOUS MODE FORCED CONTINUOUS MODE VOUT PRE-BIASED TO 0.75V FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND
Overcurrent Protection Short-Circuit Protection Overvoltage Protection
SHORT- CIRCUIT IL IL TRIGGER 10A/DIV 5A/DIV V OVERVOLTAGE CREATED BY APPLYING FULL CURRENT LIMIT OUT V A CHARGED CAPACITOR TO V 1V/DIV OUT OUT WHEN V 100mV/DIV OUT HIGHER CURRENT LIMIT STARTS TO FOLD BACK AS THAN HALF OF REGULATED VOUT DROPS BELOW HALF OF REGULATED AC-COUPLED I C V L OUT OUT 10A/DIV RECHARGE BG1 100mV/DIV 5V/DIV AC-COUPLED 5ms/DIV 3838 G12 VIN = 12V 500µs/DIV 3838 G13 VIN = 12V 20µs/DIV 3838 G14 VIN = 12V VOUT = 1.2V VOUT = 1.2V VOUT = 1.2V BG STAYS ON UNTIL FORCED CONTINUOUS MODE ILOAD = 0A FORCED CONTINUOUS VOUT IS PULLED CURRENT LIMIT = 17A FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND MODE BELOW OVERVOLTAGE OVERLOAD = 7.5A TO 17.5A ILOAD = 0A THRESHOLD FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND FIGURE 17 CIRCUIT, CHANNEL 1, VRNG1 = SGND
Phase Relationship: Phase Relationship: Phase Relationship: PHASMD = Ground PHASMD = Float PHASMD = INTVCC
PLLIN PLLIN PLLIN 5V/DIV 5V/DIV 5V/DIV SW1 SW1 SW1 0° 10V/DIV 0° 10V/DIV 0° 10V/DIV SW2 SW2 SW2 10V/DIV 180° 10V/DIV 180° 10V/DIV 240° CLKOUT CLKOUT CLKOUT 60° 5V/DIV 5V/DIV 90° 5V/DIV 120° 500ns/DIV 3838 G15 500ns/DIV 3838 G15 500ns/DIV 3838 G17 FIGURE 19 CIRCUIT FIGURE 19 CIRCUIT FIGURE 19 CIRCUIT VIN = 12V VIN = 12V VIN = 12V VOUT1 = 5V, VOUT2 = 3.3V VOUT1 = 5V, VOUT2 = 3.3V VOUT1 = 5V, VOUT2 = 3.3V LOAD = 0A LOAD = 0A LOAD = 0A MODE/PLLIN = 333kHz EXTERNAL CLOCK MODE/PLLIN = 333kHz EXTERNAL CLOCK MODE/PLLIN = 333kHz EXTERNAL CLOCK 3838fb For more information www.linear.com/LTC3838 7 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts
