Datasheet LTC3867 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | Synchronous Step-Down DC/DC Controller with Differential Remote Sense and Nonlinear Control |
| Pages / Page | 36 / 8 — TYPICAL PERFORMANCE CHARACTERISTICS. TK/SS Pull-Up Current. vs … |
| File Format / Size | PDF / 394 Kb |
| Document Language | English |
TYPICAL PERFORMANCE CHARACTERISTICS. TK/SS Pull-Up Current. vs Temperature. Shutdown Current vs Input Voltage
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LTC3867
TYPICAL PERFORMANCE CHARACTERISTICS TK/SS Pull-Up Current vs Temperature Shutdown Current vs Input Voltage Shutdown Current vs Temperature
1.4 50 60 40 50 1.3 30 40 1.2 20 30 TK/SS CURRENT (µA) 1.1 SHUTDOWN CURRENT (µA) 10 SHUTDOWN CURRENT (µA) 20 1.0 0 10 –50 –25 0 25 50 75 100 125 5 10 15 20 25 30 35 40 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) INPUT VOLTAGE (V) TEMPERATURE (°C) 3867 G13 3867 G19 3867 G20
PIN FUNCTIONS RUN (Pin 1):
Run Control Input. A voltage above 1.22V
SENSE+ (Pin 9):
Current Sense Comparator Input. The (+) turns on the IC. There is a 1µA pull-up current on this pin. input to the current comparator is normally connected to Once the RUN pin rises above the 1.22V threshold the the midpoint of the inductor’s parallel RC sense circuit or pull-up increases to 5µA. the inductor side of the current sensing resistor.
DIFF+ (Pin 2):
Remote Sense Differential Amplifier Non-
SENSE– (Pin 10):
Current Sense Comparator Input. The inverting Input. Connect to Feedback divider center tap (–) input to the current comparator is normally connected with the divider across the output load. to VOUT.
DIFF– (Pin 3):
Remote Sense Differential Amplifier Invert-
ILIM (Pin 11):
Current Comparator Sense Voltage Limit ing Input. Connect to sense ground at the output load. Selection Pin.
DIFFOUT (Pin 4):
Differential Amplifier Output.
ITSD (Pin 12):
Inductor Temperature-Based Thermal Shut-
V
down. Sources a 20µA current. Use a Murata PRF18 series
FB (Pin 5):
Error Amplifier Inverting Input. Connect to DIFFOUT for remote V PTC to ground. Grounding this pin disables this function. OUT sensing.
I ITEMP (Pin 13):
Input of the Temperature Sensing Com-
TH (Pin 6):
Current Control Thresholds and Error Amplifier Compensation Point. The current comparator’s threshold parators. Connect this pin to an external NTC resistor increases with the I placed near the inductor. Floating this pin disables the TH control voltage. DCR temperature compensation function.
IFAST (Pin 7):
Programming Pin for Nonlinear Control Trip Threshold. A resistor to SGND programs the trip threshold
EXTVCC (Pin 14):
External Power Input to an Internal Switch for the nonlinear control circuit. Connect to INTV Connected to INTVCC. This switch closes and supplies the CC to disable this function. IC power, bypassing the internal 5.3V regulator, whenever EXTVCC is higher than 4.7V. Do not exceed 6V.
TK/SS (Pin 8):
Output Voltage Tracking and Soft-Start Input. The voltage ramp rate at this pin sets the voltage ramp
VIN (Pin 15):
Main Input Supply. Decouple this pin to rate of the output. A capacitor to ground accomplishes PGND with a capacitor (0.1µF to 1µF) soft-start. This pin has a 1.25µA pull-up current. 3867f 8 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts
TYPICAL PERFORMANCE CHARACTERISTICS TK/SS Pull-Up Current vs Temperature Shutdown Current vs Input Voltage Shutdown Current vs Temperature
1.4 50 60 40 50 1.3 30 40 1.2 20 30 TK/SS CURRENT (µA) 1.1 SHUTDOWN CURRENT (µA) 10 SHUTDOWN CURRENT (µA) 20 1.0 0 10 –50 –25 0 25 50 75 100 125 5 10 15 20 25 30 35 40 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) INPUT VOLTAGE (V) TEMPERATURE (°C) 3867 G13 3867 G19 3867 G20
PIN FUNCTIONS RUN (Pin 1):
Run Control Input. A voltage above 1.22V
SENSE+ (Pin 9):
Current Sense Comparator Input. The (+) turns on the IC. There is a 1µA pull-up current on this pin. input to the current comparator is normally connected to Once the RUN pin rises above the 1.22V threshold the the midpoint of the inductor’s parallel RC sense circuit or pull-up increases to 5µA. the inductor side of the current sensing resistor.
DIFF+ (Pin 2):
Remote Sense Differential Amplifier Non-
SENSE– (Pin 10):
Current Sense Comparator Input. The inverting Input. Connect to Feedback divider center tap (–) input to the current comparator is normally connected with the divider across the output load. to VOUT.
DIFF– (Pin 3):
Remote Sense Differential Amplifier Invert-
ILIM (Pin 11):
Current Comparator Sense Voltage Limit ing Input. Connect to sense ground at the output load. Selection Pin.
DIFFOUT (Pin 4):
Differential Amplifier Output.
ITSD (Pin 12):
Inductor Temperature-Based Thermal Shut-
V
down. Sources a 20µA current. Use a Murata PRF18 series
FB (Pin 5):
Error Amplifier Inverting Input. Connect to DIFFOUT for remote V PTC to ground. Grounding this pin disables this function. OUT sensing.
I ITEMP (Pin 13):
Input of the Temperature Sensing Com-
TH (Pin 6):
Current Control Thresholds and Error Amplifier Compensation Point. The current comparator’s threshold parators. Connect this pin to an external NTC resistor increases with the I placed near the inductor. Floating this pin disables the TH control voltage. DCR temperature compensation function.
IFAST (Pin 7):
Programming Pin for Nonlinear Control Trip Threshold. A resistor to SGND programs the trip threshold
EXTVCC (Pin 14):
External Power Input to an Internal Switch for the nonlinear control circuit. Connect to INTV Connected to INTVCC. This switch closes and supplies the CC to disable this function. IC power, bypassing the internal 5.3V regulator, whenever EXTVCC is higher than 4.7V. Do not exceed 6V.
TK/SS (Pin 8):
Output Voltage Tracking and Soft-Start Input. The voltage ramp rate at this pin sets the voltage ramp
VIN (Pin 15):
Main Input Supply. Decouple this pin to rate of the output. A capacitor to ground accomplishes PGND with a capacitor (0.1µF to 1µF) soft-start. This pin has a 1.25µA pull-up current. 3867f 8 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts
