Datasheet LTC3858-2 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | Low IQ, Dual 2-Phase Synchronous Step-Down Controller |
| Pages / Page | 40 / 9 — PIN FUNCTIONS. INTVCC (Pin 19):. TG1, TG2 (Pin 26, Pin 15):. PGOOD1, … |
| File Format / Size | PDF / 448 Kb |
| Document Language | English |
PIN FUNCTIONS. INTVCC (Pin 19):. TG1, TG2 (Pin 26, Pin 15):. PGOOD1, PGOOD2 (Pin 27, Pin 14):. EXTVCC (Pin 20):
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Text Version of Document
LTC3858-2
PIN FUNCTIONS INTVCC (Pin 19):
Output of the Internal Linear Low Dropout
TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for Regulator. The driver and control circuits are powered from Top N-Channel MOSFETs. These are the outputs of float- this voltage source. Must be decoupled to power ground ing drivers with a voltage swing equal to INTVCC – 0.5V with a minimum of 4.7μF ceramic or other low ESR ca- superimposed on the switch node voltage SW. pacitor. Do not use the INTVCC pin for any other purpose.
PGOOD1, PGOOD2 (Pin 27, Pin 14):
Open-Drain Logic
EXTVCC (Pin 20):
External Power Input to an Internal LDO Output. PGOOD1,2 is pulled to ground when the voltage Connected to INTVCC. This LDO supplies INTVCC power, on the VFB1,2 pin is not within ±10% of its set point. bypassing the internal LDO powered from VIN whenever
SS1, SS2 (Pin 29, Pin 13):
External Soft-Start Input. The EXTVCC is higher than 4.7V. See EXTVCC Connection in LTC3858-2 regulates the V the Applications Information section. Do not exceed 14V FB1,2 voltage to the smaller of 0.8V or the voltage on the SS1,2 pin. An internal 1μA pull- on this pin. up current source is connected to this pin. A capacitor to
PGND (Pin 21):
Driver Power Ground. Connects to the ground at this pin sets the ramp time to final regulated sources of bottom (synchronous) N-channel MOSFETs output voltage. Alternatively, a resistor divider on another and the (–) terminal(s) of CIN. voltage supply connected to this pin allows the LTC3858-2
V
output to track the other supply during start-up.
IN (Pin 22):
Main Input Supply Pin. A bypass capacitor should be tied between this pin and the signal ground pin.
ITH1, ITH2 (Pin 30, Pin 12):
Error Amplifier Outputs and
BG1, BG2 (Pin 23, Pin 18):
High Current Gate Drives Switching Regulator Compensation Points. Each associ- for Bottom (Synchronous) N-Channel MOSFETs. Voltage ated channel’s current comparator trip point increases swing at these pins is from ground to INTV with this control voltage. CC.
BOOST1, BOOST2 (Pin 24, Pin 17):
Bootstrapped Supplies
VFB1, VFB2 (Pin 31, Pin 11):
Receives the remotely sensed to the Topside Floating Drivers. Capacitors are connected feedback voltage for each controller from an external between the BOOST and SW pins and Schottky diodes are resistive divider across the output. tied between the BOOST and INTVCC pins. Voltage swing
SENSE1+, SENSE2+ (Pin 32, Pin 10):
The (+) Input to at the BOOST pins is from INTVCC to (VIN + INTVCC). the differential current comparators that are normally
SW1, SW2 (Pin 25, Pin 16):
Switch Node Connections connected to inductor DCR sensing networks or current to Inductors. sensing resistors. The ITH pin voltage and controlled offsets between the SENSE– and SENSE+ pins in conjunction with RSENSE set the current trip threshold. 38582f 9
PIN FUNCTIONS INTVCC (Pin 19):
Output of the Internal Linear Low Dropout
TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for Regulator. The driver and control circuits are powered from Top N-Channel MOSFETs. These are the outputs of float- this voltage source. Must be decoupled to power ground ing drivers with a voltage swing equal to INTVCC – 0.5V with a minimum of 4.7μF ceramic or other low ESR ca- superimposed on the switch node voltage SW. pacitor. Do not use the INTVCC pin for any other purpose.
PGOOD1, PGOOD2 (Pin 27, Pin 14):
Open-Drain Logic
EXTVCC (Pin 20):
External Power Input to an Internal LDO Output. PGOOD1,2 is pulled to ground when the voltage Connected to INTVCC. This LDO supplies INTVCC power, on the VFB1,2 pin is not within ±10% of its set point. bypassing the internal LDO powered from VIN whenever
SS1, SS2 (Pin 29, Pin 13):
External Soft-Start Input. The EXTVCC is higher than 4.7V. See EXTVCC Connection in LTC3858-2 regulates the V the Applications Information section. Do not exceed 14V FB1,2 voltage to the smaller of 0.8V or the voltage on the SS1,2 pin. An internal 1μA pull- on this pin. up current source is connected to this pin. A capacitor to
PGND (Pin 21):
Driver Power Ground. Connects to the ground at this pin sets the ramp time to final regulated sources of bottom (synchronous) N-channel MOSFETs output voltage. Alternatively, a resistor divider on another and the (–) terminal(s) of CIN. voltage supply connected to this pin allows the LTC3858-2
V
output to track the other supply during start-up.
IN (Pin 22):
Main Input Supply Pin. A bypass capacitor should be tied between this pin and the signal ground pin.
ITH1, ITH2 (Pin 30, Pin 12):
Error Amplifier Outputs and
BG1, BG2 (Pin 23, Pin 18):
High Current Gate Drives Switching Regulator Compensation Points. Each associ- for Bottom (Synchronous) N-Channel MOSFETs. Voltage ated channel’s current comparator trip point increases swing at these pins is from ground to INTV with this control voltage. CC.
BOOST1, BOOST2 (Pin 24, Pin 17):
Bootstrapped Supplies
VFB1, VFB2 (Pin 31, Pin 11):
Receives the remotely sensed to the Topside Floating Drivers. Capacitors are connected feedback voltage for each controller from an external between the BOOST and SW pins and Schottky diodes are resistive divider across the output. tied between the BOOST and INTVCC pins. Voltage swing
SENSE1+, SENSE2+ (Pin 32, Pin 10):
The (+) Input to at the BOOST pins is from INTVCC to (VIN + INTVCC). the differential current comparators that are normally
SW1, SW2 (Pin 25, Pin 16):
Switch Node Connections connected to inductor DCR sensing networks or current to Inductors. sensing resistors. The ITH pin voltage and controlled offsets between the SENSE– and SENSE+ pins in conjunction with RSENSE set the current trip threshold. 38582f 9
