Datasheet LTC3774 (Analog Devices) - 8
| Manufacturer | Analog Devices |
| Description | Dual, Multiphase Current Mode Synchronous Controller for Sub-Milliohm DCR Sensing |
| Pages / Page | 38 / 8 — PIN FUNCTIONS PGOOD1, PGOOD2 (Pin 15, Pin 14):. OSNS1 , VOSNS2 (Pin 26, … |
| File Format / Size | PDF / 426 Kb |
| Document Language | English |
PIN FUNCTIONS PGOOD1, PGOOD2 (Pin 15, Pin 14):. OSNS1 , VOSNS2 (Pin 26, Pin 3):. SNSA1+, SNSA2+ (Pin 16, Pin 13):
Model Line for this Datasheet
Text Version of Document
LTC3774
PIN FUNCTIONS PGOOD1, PGOOD2 (Pin 15, Pin 14):
Power Good Indica-
V – – OSNS1 , VOSNS2 (Pin 26, Pin 3):
Remote Sense Differ- tor Outputs. Open drain outputs that pull to ground when ential Amplifier Inverting inputs. Connect to sense ground output voltage is not in regulation. at the output load.
SNSA1+, SNSA2+ (Pin 16, Pin 13):
AC Current Sense
ITH1, ITH2 (Pin 27, Pin 2):
Current Control Thresholds Comparator (+) Inputs. This input senses the signal from and Error Amplifier Compensation Points. The current the output inductor’s DCR with a filter bandwidth of five comparator’s threshold increases with the ITH control times larger than the inductor’s L/DCR value. voltage.
SNS1–, SNS2– (Pin 17, Pin 12):
Negative current Sense
ITEMP1, ITEMP2 (Pin 28, Pin 1):
Input of the temperature Inputs. The negative input of the current comparator is sensing comparators. Connect this pin to an external NTC normally connected to the output. resistor placed near the inductors. Floating this pin disables
SNSD1+, SNSD2+ (Pin 18, Pin 11):
DC Current Sense the DCR temperature compensation function. Comparator (+) Inputs. This input senses the signal from
ILIM1, ILIM2 (Pin 29, Pin 36):
Current Comparator Sense the output inductor’s DCR with a filter bandwidth equal to Voltage Limit Selection pins. the inductor’s L/DCR value.
PHSMD (Pin 30):
Phase Mode Pin. This pin selects CH1-
RUN1, RUN2 (Pin 20, Pin 9):
Run Control Inputs. A volt- CH2 and CH1-CLKOUT phase relationships. age above 1.22V turns on the IC. There is a 1µA pull-up
FREQ (Pin 31):
Frequency Set/Select Pin. A resistor current on this pin. Once the RUN pin rises above the between this pin and GND sets the switching frequency. 1.22V threshold the pull-up increases to 5µA. This pin sources 20uA.
PMW1, PWM2 (Pin 21, Pin 8):
(Top) Gate Signal Outputs.
MODE/PLLIN (Pin 32):
Dual Function Pin. Tying this pin This signal goes to the PWM or top gate input of the ex- to GND, INTV ternal gate driver or integrated driver MOSFET or Power CC or floating it enables forced continuous mode, pulse-skipping mode or Burst Mode operation re- Block. This is a three-state compatible output. spectively. Applying a clock signal to this pin causes the
PWMEN1, PWMEN2 (Pin 22, Pin 7):
Enable pins for non- internal PLL to synchronize the internal oscillator to the three-state compatible drivers. This pin has an internal clock signal and forces forced continuous mode. The PLL open-drain pull-up to INTVCC. An external resistor to GND compensation network is integrated on to the IC. is required. This pin is low when the corresponding PWM
CLKOUT (Pin 33):
Clock Output Pin. This pin is used to pin is high impedance. synchronize other LTC3774s.
HIZB1, HIZB2 (Pin 23, Pin 6):
Phase Shedding Input Pins.
INTV
When this pin is low, the corresponding PWM pin goes
CC (Pin 34):
Internal 5.5V Regulator Output. The con- trol circuits are powered from this voltage. Decouple this high impedance and PWMEN goes low. Tie to INTVCC or pin to GND with a minimum of 4.7µF low ESR tantalum VIN to disable this function. or ceramic capacitor. This pin is intended to be used as a
TK/SS1, TK/SS2 (Pin 24, Pin 5):
Output Voltage Tracking reference only. Please do not bias other applications off and Soft-Start Inputs. The voltage ramp rate at this pin this voltage! sets the voltage ramp rate of the output. A capacitor to
V
ground accomplishes soft-start. This pin has a 1.25µA
IN (Pin 35):
Main Input Supply. Decouple this pin to GND with a capacitor (0.1µF to 1µF) pull-up current.
GND (Pins 19, 10, Exposed Pad Pin 37):
Ground. All
V + + OSNS1 , VOSNS2 (Pin 25, Pin 4):
Remote Sense Differ- small-signal components and compensation components ential Amplifier Non-inverting Inputs. Connect to Feedback should be connected here. The exposed pad must be divider center tap with the divider across the output load. soldered to the PCB ground for electrical connection and The remote sense differential amplifier’s output is internally rated thermal performance. connected to the error amplifier inverting input. 3774fc 8 For more information www.linear.com/LTC3774 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
PIN FUNCTIONS PGOOD1, PGOOD2 (Pin 15, Pin 14):
Power Good Indica-
V – – OSNS1 , VOSNS2 (Pin 26, Pin 3):
Remote Sense Differ- tor Outputs. Open drain outputs that pull to ground when ential Amplifier Inverting inputs. Connect to sense ground output voltage is not in regulation. at the output load.
SNSA1+, SNSA2+ (Pin 16, Pin 13):
AC Current Sense
ITH1, ITH2 (Pin 27, Pin 2):
Current Control Thresholds Comparator (+) Inputs. This input senses the signal from and Error Amplifier Compensation Points. The current the output inductor’s DCR with a filter bandwidth of five comparator’s threshold increases with the ITH control times larger than the inductor’s L/DCR value. voltage.
SNS1–, SNS2– (Pin 17, Pin 12):
Negative current Sense
ITEMP1, ITEMP2 (Pin 28, Pin 1):
Input of the temperature Inputs. The negative input of the current comparator is sensing comparators. Connect this pin to an external NTC normally connected to the output. resistor placed near the inductors. Floating this pin disables
SNSD1+, SNSD2+ (Pin 18, Pin 11):
DC Current Sense the DCR temperature compensation function. Comparator (+) Inputs. This input senses the signal from
ILIM1, ILIM2 (Pin 29, Pin 36):
Current Comparator Sense the output inductor’s DCR with a filter bandwidth equal to Voltage Limit Selection pins. the inductor’s L/DCR value.
PHSMD (Pin 30):
Phase Mode Pin. This pin selects CH1-
RUN1, RUN2 (Pin 20, Pin 9):
Run Control Inputs. A volt- CH2 and CH1-CLKOUT phase relationships. age above 1.22V turns on the IC. There is a 1µA pull-up
FREQ (Pin 31):
Frequency Set/Select Pin. A resistor current on this pin. Once the RUN pin rises above the between this pin and GND sets the switching frequency. 1.22V threshold the pull-up increases to 5µA. This pin sources 20uA.
PMW1, PWM2 (Pin 21, Pin 8):
(Top) Gate Signal Outputs.
MODE/PLLIN (Pin 32):
Dual Function Pin. Tying this pin This signal goes to the PWM or top gate input of the ex- to GND, INTV ternal gate driver or integrated driver MOSFET or Power CC or floating it enables forced continuous mode, pulse-skipping mode or Burst Mode operation re- Block. This is a three-state compatible output. spectively. Applying a clock signal to this pin causes the
PWMEN1, PWMEN2 (Pin 22, Pin 7):
Enable pins for non- internal PLL to synchronize the internal oscillator to the three-state compatible drivers. This pin has an internal clock signal and forces forced continuous mode. The PLL open-drain pull-up to INTVCC. An external resistor to GND compensation network is integrated on to the IC. is required. This pin is low when the corresponding PWM
CLKOUT (Pin 33):
Clock Output Pin. This pin is used to pin is high impedance. synchronize other LTC3774s.
HIZB1, HIZB2 (Pin 23, Pin 6):
Phase Shedding Input Pins.
INTV
When this pin is low, the corresponding PWM pin goes
CC (Pin 34):
Internal 5.5V Regulator Output. The con- trol circuits are powered from this voltage. Decouple this high impedance and PWMEN goes low. Tie to INTVCC or pin to GND with a minimum of 4.7µF low ESR tantalum VIN to disable this function. or ceramic capacitor. This pin is intended to be used as a
TK/SS1, TK/SS2 (Pin 24, Pin 5):
Output Voltage Tracking reference only. Please do not bias other applications off and Soft-Start Inputs. The voltage ramp rate at this pin this voltage! sets the voltage ramp rate of the output. A capacitor to
V
ground accomplishes soft-start. This pin has a 1.25µA
IN (Pin 35):
Main Input Supply. Decouple this pin to GND with a capacitor (0.1µF to 1µF) pull-up current.
GND (Pins 19, 10, Exposed Pad Pin 37):
Ground. All
V + + OSNS1 , VOSNS2 (Pin 25, Pin 4):
Remote Sense Differ- small-signal components and compensation components ential Amplifier Non-inverting Inputs. Connect to Feedback should be connected here. The exposed pad must be divider center tap with the divider across the output load. soldered to the PCB ground for electrical connection and The remote sense differential amplifier’s output is internally rated thermal performance. connected to the error amplifier inverting input. 3774fc 8 For more information www.linear.com/LTC3774 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Typical Application Related Parts
