Datasheet LT3980 (Analog Devices) - 7
| Fabricante | Analog Devices |
| Descripción | 58V, 2A, 2.4MHz Step-Down Switching Regulator with 85μA Quiescent Current |
| Páginas / Página | 24 / 7 — pin FuncTions (DFN, MSOP). SYNC (Pin 1/Pin 1):. RUN/SS (Pin 8/Pin 9):. NC … |
| Formato / tamaño de archivo | PDF / 334 Kb |
| Idioma del documento | Inglés |
pin FuncTions (DFN, MSOP). SYNC (Pin 1/Pin 1):. RUN/SS (Pin 8/Pin 9):. NC (Pins 2, 13/Pins 3, 5, 13, 16):. BD (Pin 9/Pin 10):
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LT3980
pin FuncTions (DFN, MSOP) SYNC (Pin 1/Pin 1):
This is the external clock synchro- must be soldered to the PCB. nization input. Ground this pin for low ripple Burst Mode
RUN/SS (Pin 8/Pin 9):
The RUN/SS pin is used to put the operation at low output loads. Tie to a voltage above 0.8V LT3980 in shutdown mode. Tie to ground to shut down to select pulse-skipping mode. Tie to a clock source for the LT3980. Tie to 2.5V or more for normal operation. If synchronization. Clock edges should have rise and fall the shutdown feature is not used, tie this pin to the V times faster than 1µs. Tie pin to GND if not used. See the IN pin. RUN/SS also provides a soft-start function; see the Synchronization section in Applications Information. Applications Information section.
NC (Pins 2, 13/Pins 3, 5, 13, 16):
No Connect. These
BD (Pin 9/Pin 10):
This pin connects to the anode of the pins are not connected to internal circuitry. boost Schottky diode. BD also supplies current to the
PG (Pin 3/Pin 2):
The PG pin is the open collector output internal regulator. of an internal comparator. PG remains low until the FB pin
BOOST (Pin 10/Pin 11):
This pin is used to provide a drive is within 9% of the final regulation voltage. PG output is voltage, higher than the input voltage, to the internal bipolar valid when VIN is above 3.6V and RUN/SS is high. NPN power switch.
FB (Pin 4/Pin 4):
The LT3980 regulates the FB pin to 0.790V. Connect the feedback resistor divider tap to this pin.
SW (Pin 11/Pin 12):
The SW pin is the output of the internal power switch. Connect this pin to the inductor,
VC (Pin 5/Pin 6):
The VC pin is the output of the internal catch diode and boost capacitor. error amplifier. The voltage on this pin controls the peak switch current. Tie an RC network from this pin to ground
VIN (Pin 12/Pin 14):
The VIN pin supplies current to the to compensate the control loop. LT3980’s internal regulator and to the internal power switch. This pin must be locally bypassed.
RT (Pin 6/Pin 7):
Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching
DA (Pin 14/Pin 15):
This pin measures catch diode current frequency. and pauses the oscillator during overcurrent conditions.
GND (Pin 7, 15/Pin 8, 17):
Ground. The exposed pads
block DiaGram
VIN VIN – C1 INTERNAL 0.79V REF + BD RUN/SS Σ SLOPE COMP SWITCH BOOST LATCH R C3 RT OSCILLATOR Q 100kHzTO2.4MHz S RT SW L1 VOUT SYNC DISABLE C2 D1 BurstMode DA SOFT-START DETECT PG ERROR AMP V + 0.725V + C CLAMP VC – – CC CF GND FB RC R2 R1 3680 BD 3980fa For more information www.linear.com/LT3980 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
pin FuncTions (DFN, MSOP) SYNC (Pin 1/Pin 1):
This is the external clock synchro- must be soldered to the PCB. nization input. Ground this pin for low ripple Burst Mode
RUN/SS (Pin 8/Pin 9):
The RUN/SS pin is used to put the operation at low output loads. Tie to a voltage above 0.8V LT3980 in shutdown mode. Tie to ground to shut down to select pulse-skipping mode. Tie to a clock source for the LT3980. Tie to 2.5V or more for normal operation. If synchronization. Clock edges should have rise and fall the shutdown feature is not used, tie this pin to the V times faster than 1µs. Tie pin to GND if not used. See the IN pin. RUN/SS also provides a soft-start function; see the Synchronization section in Applications Information. Applications Information section.
NC (Pins 2, 13/Pins 3, 5, 13, 16):
No Connect. These
BD (Pin 9/Pin 10):
This pin connects to the anode of the pins are not connected to internal circuitry. boost Schottky diode. BD also supplies current to the
PG (Pin 3/Pin 2):
The PG pin is the open collector output internal regulator. of an internal comparator. PG remains low until the FB pin
BOOST (Pin 10/Pin 11):
This pin is used to provide a drive is within 9% of the final regulation voltage. PG output is voltage, higher than the input voltage, to the internal bipolar valid when VIN is above 3.6V and RUN/SS is high. NPN power switch.
FB (Pin 4/Pin 4):
The LT3980 regulates the FB pin to 0.790V. Connect the feedback resistor divider tap to this pin.
SW (Pin 11/Pin 12):
The SW pin is the output of the internal power switch. Connect this pin to the inductor,
VC (Pin 5/Pin 6):
The VC pin is the output of the internal catch diode and boost capacitor. error amplifier. The voltage on this pin controls the peak switch current. Tie an RC network from this pin to ground
VIN (Pin 12/Pin 14):
The VIN pin supplies current to the to compensate the control loop. LT3980’s internal regulator and to the internal power switch. This pin must be locally bypassed.
RT (Pin 6/Pin 7):
Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching
DA (Pin 14/Pin 15):
This pin measures catch diode current frequency. and pauses the oscillator during overcurrent conditions.
GND (Pin 7, 15/Pin 8, 17):
Ground. The exposed pads
block DiaGram
VIN VIN – C1 INTERNAL 0.79V REF + BD RUN/SS Σ SLOPE COMP SWITCH BOOST LATCH R C3 RT OSCILLATOR Q 100kHzTO2.4MHz S RT SW L1 VOUT SYNC DISABLE C2 D1 BurstMode DA SOFT-START DETECT PG ERROR AMP V + 0.725V + C CLAMP VC – – CC CF GND FB RC R2 R1 3680 BD 3980fa For more information www.linear.com/LT3980 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts