Datasheet LTC7892 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | Low IQ, Dual, 2-Phase Synchronous Boost Controller for GaN FETs in 40-Lead QFN (6mm x 6mm, Plastic Side Wettable) package |
| Pages / Page | 50 / 10 — Data Sheet. LTC7892. PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS. + 1. – … |
| File Format / Size | PDF / 1.0 Mb |
| Document Language | English |
Data Sheet. LTC7892. PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS. + 1. – 1. B F. SS1. 40 39 38 37 36 35 34 33 32 31. FREQ 1. 30 BOOST1
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Text Version of Document
Data Sheet LTC7892 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS + 1 – 1 1 E E 1 D 1 1 S S G O P N N N 1 1 R O U D 1 E E B F H P G G G W S S V TI SS1 V P T T S 40 39 38 37 36 35 34 33 32 31 FREQ 1 30 BOOST1 MODE 2 29 BGDN1 PLLIN/SPREAD 3 28 BGUP1 RUN1 4 27 V LTC7892 BIAS TOP VIEW RUN2 5 26 EXTV (Not to Scale) CC GND 6 25 INTVCC 41 DRVUV 7 GND 24 DRVCC DRVSET 8 23 BGUP2 DTCA 9 22 BGDN2 DTCB 10 21 BOOST2 11 12 13 14 15 16 17 18 19 20 + 2 – 2 2 2 2 2 2 2 B E E F H D P N W S S V TI SS2 ILIM O U D S N N O G G E E G T T S S P NOTES 1. THE EXPOSED PAD (PIN 41) MUST BE SOLDERED TO PCB GROUND FOR RATED ELECTRICAL AND THERMAL PERFORMANCE.
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Figure 3. Pin Configuration Table 3. Pin Descriptions PIN NAME DESCRIPTION
Frequency Control pin for the internal Voltage Controlled Oscillator (VCO). Connect FREQ to GND for a fixed frequency of 370kHz. Connect FREQ to INTV 1 FREQ CC for a fixed frequency of 2.25MHz. Program frequencies between 100kHz and 3MHz by using a resistor between FREQ and GND. Minimize the capacitance on FREQ. Mode Select Input. This input determines how the LTC7892 operates at light loads. Connect MODE to GND to select Burst Mode® operation. An internal 100kΩ resistor to 2 MODE GND also invokes Burst Mode operation when MODE is floating. Connect MODE to INTVCC to force continuous inductor current operation. Tying MODE to INTVCC through a 100kΩ resistor selects the PS operation. External Synchronization Input to Phase Detector/Spread Spectrum Enable. When an external clock is applied to PLLIN/SPREAD, the PLL forces the rising BGxx1 signal to PLLIN/ 3 synchronize with the rising edge of the external clock. When not synchronizing to an SPREAD external clock, tie this input to INTVCC to enable spread spectrum dithering of the oscillator, or to GND to disable spread spectrum dithering. Run Control Input for Channel 1. Forcing RUN1 less than 1.08V disables controller 4 RUN1 switching. Forcing RUN1 and RUN2 less than 0.7V shuts down the LTC7892, reducing IQ to approximately 1μA. Tie the RUN1 pin to VBIAS to ensure it is always in operation.
analog.com
Rev. 0 10 of 50 Document Outline Features Applications General Description Typical Application Revision History Specifications Absolute Maximum Ratings Pin Configurations and Function Descriptions Typical Performance Characteristics Functional Diagram Theory of Operation Main Control Loop Power and Bias Supplies (VBIAS, EXTVCC, DRVCC, INTVCC) High Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Start-Up and Shutdown (RUN and SS Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) Output Overvoltage Protection Power Good Applications Information Inductor Value Calculation Inductor Core Selection Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Current Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Dead Time Control (DTCA and DTCB Pins) DTCx Pin Tied to Ground (Adaptive Dead Time Control) DTCx Pin connected with a resistor to GND Power FET Selection CIN and COUT Selection Single Output 2-Phase Operation Setting the Output Voltage RUNx Pins and Undervoltage Lockout Soft Start (SSx Pins) INTVCC Regulators (OPTI-DRIVE) Topside FET Driver Supply (CB) Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Design Example PCB Board Layout Checklist PCB Layout Debugging Typical Applications Related Parts Outline Dimensions Ordering Guide
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Figure 3. Pin Configuration Table 3. Pin Descriptions PIN NAME DESCRIPTION
Frequency Control pin for the internal Voltage Controlled Oscillator (VCO). Connect FREQ to GND for a fixed frequency of 370kHz. Connect FREQ to INTV 1 FREQ CC for a fixed frequency of 2.25MHz. Program frequencies between 100kHz and 3MHz by using a resistor between FREQ and GND. Minimize the capacitance on FREQ. Mode Select Input. This input determines how the LTC7892 operates at light loads. Connect MODE to GND to select Burst Mode® operation. An internal 100kΩ resistor to 2 MODE GND also invokes Burst Mode operation when MODE is floating. Connect MODE to INTVCC to force continuous inductor current operation. Tying MODE to INTVCC through a 100kΩ resistor selects the PS operation. External Synchronization Input to Phase Detector/Spread Spectrum Enable. When an external clock is applied to PLLIN/SPREAD, the PLL forces the rising BGxx1 signal to PLLIN/ 3 synchronize with the rising edge of the external clock. When not synchronizing to an SPREAD external clock, tie this input to INTVCC to enable spread spectrum dithering of the oscillator, or to GND to disable spread spectrum dithering. Run Control Input for Channel 1. Forcing RUN1 less than 1.08V disables controller 4 RUN1 switching. Forcing RUN1 and RUN2 less than 0.7V shuts down the LTC7892, reducing IQ to approximately 1μA. Tie the RUN1 pin to VBIAS to ensure it is always in operation.
analog.com
Rev. 0 10 of 50 Document Outline Features Applications General Description Typical Application Revision History Specifications Absolute Maximum Ratings Pin Configurations and Function Descriptions Typical Performance Characteristics Functional Diagram Theory of Operation Main Control Loop Power and Bias Supplies (VBIAS, EXTVCC, DRVCC, INTVCC) High Side Bootstrap Capacitor Dead Time Control (DTCA and DTCB Pins) Start-Up and Shutdown (RUN and SS Pins) Light Load Operation: Burst Mode Operation, Pulse-Skipping Mode, or Forced Continuous Mode (MODE Pin) Frequency Selection, Spread Spectrum, and Phase-Locked Loop (FREQ and PLLIN/SPREAD Pins) Output Overvoltage Protection Power Good Applications Information Inductor Value Calculation Inductor Core Selection Current Sense Selection Low Value Resistor Current Sensing Inductor DCR Current Sensing Setting the Operating Frequency Selecting the Light-Load Operating Mode Dead Time Control (DTCA and DTCB Pins) DTCx Pin Tied to Ground (Adaptive Dead Time Control) DTCx Pin connected with a resistor to GND Power FET Selection CIN and COUT Selection Single Output 2-Phase Operation Setting the Output Voltage RUNx Pins and Undervoltage Lockout Soft Start (SSx Pins) INTVCC Regulators (OPTI-DRIVE) Topside FET Driver Supply (CB) Minimum On-Time Considerations Fault Conditions: Overtemperature Protection Phase-Locked Loop and Frequency Synchronization Efficiency Considerations Checking Transient Response Design Example PCB Board Layout Checklist PCB Layout Debugging Typical Applications Related Parts Outline Dimensions Ordering Guide