Datasheet LTC1625 (Analog Devices) - 6
| Manufacturer | Analog Devices |
| Description | No RSENSE Current Mode Synchronous Step-Down Switching Regulator |
| Pages / Page | 24 / 6 — PIN FUNCTIONS. EXTV. CC (Pin 1):. SYNC (Pin 2):. PGND (Pin 9):. BG (Pin … |
| File Format / Size | PDF / 392 Kb |
| Document Language | English |
PIN FUNCTIONS. EXTV. CC (Pin 1):. SYNC (Pin 2):. PGND (Pin 9):. BG (Pin 10):. RUN/SS (Pin 3):. INTVCC (Pin 11):. FCB (Pin 4):
Model Line for this Datasheet
Text Version of Document
LTC1625
U U U PIN FUNCTIONS EXTV
Leaving V
CC (Pin 1):
INTVCC Switch Input. When the EXTVCC PROG open allows the output voltage to be set by voltage is above 4.7V, the switch closes and supplies an external resistive divider between the output and INTV V CC power from EXTVCC. Do not exceed 7V at this pin. OSENSE.
SYNC (Pin 2):
Synchronization Input for Internal Oscilla-
PGND (Pin 9):
Driver Power Ground. Connects to the tor. The oscillator will nominally run at 150kHz when open, source of the bottom N-channel MOSFET, the (–) terminal 225kHz when tied above 1.2V, and will lock over a 1.5:1 of CVCC and the (–) terminal of CIN. clock frequency range.
BG (Pin 10):
Bottom Gate Drive. Drives the gate of the
RUN/SS (Pin 3):
Run Control and Soft Start Input. A bottom N-channel MOSFET between ground and INTVCC. capacitor to ground at this pin sets the ramp time to full
INTVCC (Pin 11):
Internal 5.2V Regulator Output. The current output (approximately 1s/µF). Forcing this pin driver and control circuits are powered from this voltage. below 1.4V shuts down the device. Decouple this pin to power ground with a minimum of
FCB (Pin 4):
Forced Continuous Input. Tie this pin to 4.7µF tantalum capacitance. ground to force synchronous operation at low load, to a
BOOST (Pin 12):
Topside Floating Driver Supply. The (+) resistive divider from the secondary output when using terminal of the bootstrap capacitor connects here. This pin a secondary winding, or to INTVCC to enable Burst Mode swings from a diode drop below INTVCC to VIN + INTVCC. operation at low load.
TG (Pin 13):
Top Gate Drive. Drives the top N-channel
ITH (Pin 5):
Error Amplifier Compensation Point. The MOSFET with a voltage swing equal to INTVCC minus a current comparator threshold increases with this control diode drop, superimposed on the switch node voltage. voltage. Nominal voltage range for this pin is 0V to 2.4V.
SW (Pin 14):
Switch Node. The (–) terminal of the boot-
SGND (Pin 6):
Signal Ground. Connect to the (–) terminal strap capacitor connects here. This pin swings from a of COUT. diode drop below ground up to VIN.
VOSENSE (Pin 7):
Output Voltage Sense. Feedback input
TK (Pin 15):
Top MOSFET Kelvin Sense. MOSFET VDS from the remotely sensed output voltage or from an sensing requires this pin to be routed to the drain of the top external resistive divider across the output. MOSFET separately from VIN.
VPROG (Pin 8):
Output Voltage Programming. When
VIN (Pin 16):
Main Supply Input. Decouple this pin to VOSENSE is connected to the output, VPROG < 0.8V selects ground with an RC filter (4.7Ω, 0.1µF) for applications a 3.3V output and VPROG > 3.5V selects a 5V output. above 3A. 6
U U U PIN FUNCTIONS EXTV
Leaving V
CC (Pin 1):
INTVCC Switch Input. When the EXTVCC PROG open allows the output voltage to be set by voltage is above 4.7V, the switch closes and supplies an external resistive divider between the output and INTV V CC power from EXTVCC. Do not exceed 7V at this pin. OSENSE.
SYNC (Pin 2):
Synchronization Input for Internal Oscilla-
PGND (Pin 9):
Driver Power Ground. Connects to the tor. The oscillator will nominally run at 150kHz when open, source of the bottom N-channel MOSFET, the (–) terminal 225kHz when tied above 1.2V, and will lock over a 1.5:1 of CVCC and the (–) terminal of CIN. clock frequency range.
BG (Pin 10):
Bottom Gate Drive. Drives the gate of the
RUN/SS (Pin 3):
Run Control and Soft Start Input. A bottom N-channel MOSFET between ground and INTVCC. capacitor to ground at this pin sets the ramp time to full
INTVCC (Pin 11):
Internal 5.2V Regulator Output. The current output (approximately 1s/µF). Forcing this pin driver and control circuits are powered from this voltage. below 1.4V shuts down the device. Decouple this pin to power ground with a minimum of
FCB (Pin 4):
Forced Continuous Input. Tie this pin to 4.7µF tantalum capacitance. ground to force synchronous operation at low load, to a
BOOST (Pin 12):
Topside Floating Driver Supply. The (+) resistive divider from the secondary output when using terminal of the bootstrap capacitor connects here. This pin a secondary winding, or to INTVCC to enable Burst Mode swings from a diode drop below INTVCC to VIN + INTVCC. operation at low load.
TG (Pin 13):
Top Gate Drive. Drives the top N-channel
ITH (Pin 5):
Error Amplifier Compensation Point. The MOSFET with a voltage swing equal to INTVCC minus a current comparator threshold increases with this control diode drop, superimposed on the switch node voltage. voltage. Nominal voltage range for this pin is 0V to 2.4V.
SW (Pin 14):
Switch Node. The (–) terminal of the boot-
SGND (Pin 6):
Signal Ground. Connect to the (–) terminal strap capacitor connects here. This pin swings from a of COUT. diode drop below ground up to VIN.
VOSENSE (Pin 7):
Output Voltage Sense. Feedback input
TK (Pin 15):
Top MOSFET Kelvin Sense. MOSFET VDS from the remotely sensed output voltage or from an sensing requires this pin to be routed to the drain of the top external resistive divider across the output. MOSFET separately from VIN.
VPROG (Pin 8):
Output Voltage Programming. When
VIN (Pin 16):
Main Supply Input. Decouple this pin to VOSENSE is connected to the output, VPROG < 0.8V selects ground with an RC filter (4.7Ω, 0.1µF) for applications a 3.3V output and VPROG > 3.5V selects a 5V output. above 3A. 6
