Datasheet LTC3890-3 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | 60V Low IQ, Dual, 2-Phase Synchronous Step-Down DC/DC Controller |
| Pages / Page | 40 / 9 — pin FuncTions BG1, BG2 (Pin 23, Pin 18):. PGOOD1 (Pin 27):. BOOST1, … |
| File Format / Size | PDF / 1.3 Mb |
| Document Language | English |
pin FuncTions BG1, BG2 (Pin 23, Pin 18):. PGOOD1 (Pin 27):. BOOST1, BOOST2 (Pin 24, Pin 17):
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Text Version of Document
LTC3890-3
pin FuncTions BG1, BG2 (Pin 23, Pin 18):
High Current Gate Drives
PGOOD1 (Pin 27):
Open-Drain Logic Output. PGOOD1 is for Bottom (Synchronous) N-Channel MOSFETs. Voltage pulled to ground when the voltage on the VFB1 pin is not swing at these pins is from ground to INTVCC. within ±10% of its set point.
BOOST1, BOOST2 (Pin 24, Pin 17):
Bootstrapped Supplies
TRACK/SS1, TRACK/SS2 (Pin 28, Pin 14):
External Track- to the Topside Floating Drivers. Capacitors are connected ing and Soft-Start Input. The LTC3890-3 regulates the between the BOOST and SW pins and Schottky diodes are VFB1,2 voltage to the smaller of 0.8V or the voltage on the tied between the BOOST and INTVCC pins. Voltage swing TRACK/SS1,2 pin. An internal 1µA pull-up current source at the BOOST pins is from INTVCC to (VIN + INTVCC). is connected to this pin. A capacitor to ground at this
SW1, SW2 (Pin 25, Pin 16):
Switch Node Connections pin sets the ramp time to final regulated output voltage. to Inductors. Alternatively, a resistor divider on another voltage supply connected to this pin allows the LTC3890-3 output to track
TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for the other supply during start-up. Top N-Channel MOSFETs. These are the outputs of float- ing drivers with a voltage swing equal to INTVCC – 0.5V superimposed on the switch node voltage SW.
Table 1. Summary of the Differences Between the Parts in the LTC3890 Family LTC3890 LTC3890-1 LTC3890-2 LTC3890-3
ILIM Pin for Adjustable Yes No Yes No Current Sense Voltage? CLKOUT and PHASMD Pins Yes No Yes No for PolyPhase® Operation? Independent PGOOD Pins for Yes; PGOOD1 and PGOOD2 No; PGOOD1 Only Yes; PGOOD1 and PGOOD2 No; PGOOD1 Only Each Channel Overvoltage Protection Yes Yes No; BG Not Forced On No; BG Not Forced On Bottom Gate “Crowbar?” Current Foldback During Yes Yes No No Overcurrent Events Light Load Operation When Forced Continuous Forced Continuous Pulse-Skipping Pulse-Skipping Synchronized to External Clock Using PLLIN/MODE Pin SENSE Pins Common Mode Operation with SENSE Operation with SENSE Not Dependent on VFB Not Dependent on VFB Range Common Mode < 0.5V Common Mode < 0.5V Voltage. Makes It Easy to Voltage. Makes It Easy to Requires VFB < 0.65V Requires VFB < 0.65V Make a Non-synchronous Make a Non-synchronous Boost or SEPIC Converter Boost or SEPIC Converter with Ground-Referenced with Ground-Referenced Current Sensing Current Sensing 38903f For more information www.linear.com/3890-3 9 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Typical Performance Characteristics Operation Package Description Typical Application
pin FuncTions BG1, BG2 (Pin 23, Pin 18):
High Current Gate Drives
PGOOD1 (Pin 27):
Open-Drain Logic Output. PGOOD1 is for Bottom (Synchronous) N-Channel MOSFETs. Voltage pulled to ground when the voltage on the VFB1 pin is not swing at these pins is from ground to INTVCC. within ±10% of its set point.
BOOST1, BOOST2 (Pin 24, Pin 17):
Bootstrapped Supplies
TRACK/SS1, TRACK/SS2 (Pin 28, Pin 14):
External Track- to the Topside Floating Drivers. Capacitors are connected ing and Soft-Start Input. The LTC3890-3 regulates the between the BOOST and SW pins and Schottky diodes are VFB1,2 voltage to the smaller of 0.8V or the voltage on the tied between the BOOST and INTVCC pins. Voltage swing TRACK/SS1,2 pin. An internal 1µA pull-up current source at the BOOST pins is from INTVCC to (VIN + INTVCC). is connected to this pin. A capacitor to ground at this
SW1, SW2 (Pin 25, Pin 16):
Switch Node Connections pin sets the ramp time to final regulated output voltage. to Inductors. Alternatively, a resistor divider on another voltage supply connected to this pin allows the LTC3890-3 output to track
TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for the other supply during start-up. Top N-Channel MOSFETs. These are the outputs of float- ing drivers with a voltage swing equal to INTVCC – 0.5V superimposed on the switch node voltage SW.
Table 1. Summary of the Differences Between the Parts in the LTC3890 Family LTC3890 LTC3890-1 LTC3890-2 LTC3890-3
ILIM Pin for Adjustable Yes No Yes No Current Sense Voltage? CLKOUT and PHASMD Pins Yes No Yes No for PolyPhase® Operation? Independent PGOOD Pins for Yes; PGOOD1 and PGOOD2 No; PGOOD1 Only Yes; PGOOD1 and PGOOD2 No; PGOOD1 Only Each Channel Overvoltage Protection Yes Yes No; BG Not Forced On No; BG Not Forced On Bottom Gate “Crowbar?” Current Foldback During Yes Yes No No Overcurrent Events Light Load Operation When Forced Continuous Forced Continuous Pulse-Skipping Pulse-Skipping Synchronized to External Clock Using PLLIN/MODE Pin SENSE Pins Common Mode Operation with SENSE Operation with SENSE Not Dependent on VFB Not Dependent on VFB Range Common Mode < 0.5V Common Mode < 0.5V Voltage. Makes It Easy to Voltage. Makes It Easy to Requires VFB < 0.65V Requires VFB < 0.65V Make a Non-synchronous Make a Non-synchronous Boost or SEPIC Converter Boost or SEPIC Converter with Ground-Referenced with Ground-Referenced Current Sensing Current Sensing 38903f For more information www.linear.com/3890-3 9 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Typical Performance Characteristics Operation Package Description Typical Application
