Datasheet LTC3857 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | Low IQ, Dual, 2-Phase Synchronous Step-Down Controller |
| Pages / Page | 38 / 9 — PIN FUNCTIONS. TG1, TG2 (Pin 26, Pin 15):. ITH1, ITH2 (Pin 30, Pin 12):. … |
| File Format / Size | PDF / 453 Kb |
| Document Language | English |
PIN FUNCTIONS. TG1, TG2 (Pin 26, Pin 15):. ITH1, ITH2 (Pin 30, Pin 12):. PGOOD1, PGOOD2 (Pin 27, Pin 14):
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Text Version of Document
LTC3857
PIN FUNCTIONS TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for
ITH1, ITH2 (Pin 30, Pin 12):
Error Amplifier Outputs and Top N-Channel MOSFETs. These are the outputs of float- Switching Regulator Compensation Points. Each associ- ing drivers with a voltage swing equal to INTVCC – 0.5V ated channel’s current comparator trip point increases superimposed on the switch node voltage SW. with this control voltage.
PGOOD1, PGOOD2 (Pin 27, Pin 14):
Open-Drain Logic
VFB1, VFB2 (Pin 31, Pin 11):
Receives the remotely sensed Output. PGOOD1,2 is pulled to ground when the voltage feedback voltage for each controller from an external on the VFB1,2 pin is not within ±10% of its set point. resistive divider across the output.
ILIM (Pin 28):
Current Comparator Sense Voltage Range
SENSE1+, SENSE2+ (Pin 32, Pin 10):
The (+) input to the Inputs. Tying this pin to SGND, FLOAT or INTVCC sets the differential current comparators are normally connected maximum current sense threshold to one of three different to DCR sensing networks or current sensing resistors. levels for both comparators. The ITH pin voltage and controlled offsets between the SENSE– and SENSE+ pins in conjunction with R
TRACK/SS1, TRACK/SS2 (Pin 29, Pin 13):
External SENSE set the current trip threshold. Tracking and Soft-Start Input. The LTC3857 regulates the VFB1,2 voltage to the smaller of 0.8V or the voltage on the TRACK/SS1,2 pin. An internal 1μA pull-up current source is connected to this pin. A capacitor to ground at this pin sets the ramp time to final regulated output voltage. Alternatively, a resistor divider on another voltage supply connected to this pin allows the LTC3857 output to track the other supply during start-up. 3857fd 9 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
PIN FUNCTIONS TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for
ITH1, ITH2 (Pin 30, Pin 12):
Error Amplifier Outputs and Top N-Channel MOSFETs. These are the outputs of float- Switching Regulator Compensation Points. Each associ- ing drivers with a voltage swing equal to INTVCC – 0.5V ated channel’s current comparator trip point increases superimposed on the switch node voltage SW. with this control voltage.
PGOOD1, PGOOD2 (Pin 27, Pin 14):
Open-Drain Logic
VFB1, VFB2 (Pin 31, Pin 11):
Receives the remotely sensed Output. PGOOD1,2 is pulled to ground when the voltage feedback voltage for each controller from an external on the VFB1,2 pin is not within ±10% of its set point. resistive divider across the output.
ILIM (Pin 28):
Current Comparator Sense Voltage Range
SENSE1+, SENSE2+ (Pin 32, Pin 10):
The (+) input to the Inputs. Tying this pin to SGND, FLOAT or INTVCC sets the differential current comparators are normally connected maximum current sense threshold to one of three different to DCR sensing networks or current sensing resistors. levels for both comparators. The ITH pin voltage and controlled offsets between the SENSE– and SENSE+ pins in conjunction with R
TRACK/SS1, TRACK/SS2 (Pin 29, Pin 13):
External SENSE set the current trip threshold. Tracking and Soft-Start Input. The LTC3857 regulates the VFB1,2 voltage to the smaller of 0.8V or the voltage on the TRACK/SS1,2 pin. An internal 1μA pull-up current source is connected to this pin. A capacitor to ground at this pin sets the ramp time to final regulated output voltage. Alternatively, a resistor divider on another voltage supply connected to this pin allows the LTC3857 output to track the other supply during start-up. 3857fd 9 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
