Datasheet LT3474, LT3474-1 (Analog Devices) - 6
| Manufacturer | Analog Devices |
| Description | Step-Down 1A LED Driver |
| Pages / Page | 20 / 6 — PIN FUNCTIONS. DNC (Pins 1, 16):. SHDN (Pin 10):. OUT (Pin 2):. LED (Pin … |
| File Format / Size | PDF / 226 Kb |
| Document Language | English |
PIN FUNCTIONS. DNC (Pins 1, 16):. SHDN (Pin 10):. OUT (Pin 2):. LED (Pin 3):. REF (Pin 11):. VIN (Pin 4):. SW (Pin 5):. VC (Pin 12):
Model Line for this Datasheet
Text Version of Document
LT3474/LT3474-1
PIN FUNCTIONS DNC (Pins 1, 16):
Do not connect external circuitry to these
SHDN (Pin 10):
The SHDN pin is used to shut down the pins, or tie them to GND. Leave the DNC pins fl oating. switching regulator and the internal bias circuits. The 2.6V switching threshold can function as an accurate
OUT (Pin 2):
The OUT pin is the input to the current sense under-voltage lockout. Pull below 0.3V to shut down the resistor. Connect this pin to the inductor and the output LT3474/LT3474-1. Pull above 2.65V to enable the LT3474/ capacitor. LT3474-1. Tie to VIN if the SHDN function is unused.
LED (Pin 3):
The LED pin is the output of the current sense
REF (Pin 11):
The REF pin is the buffered output of the resistor. Connect the anode of the LED here. internal reference. Either tie the REF pin to the VADJ pin for
VIN (Pin 4):
The VIN pin supplies current to the internal a 1A output current, or use a resistor divider to generate a circuitry and to the internal power switch and must be lower voltage at the VADJ pin. Leave this pin unconnected locally bypassed. if unused.
SW (Pin 5):
The SW pin is the output of the internal power
VC (Pin 12):
The Vc pin is the output of the internal error switch. Connect this pin to the inductor and switching amp. The voltage on this pin controls the peak switch diode. current. Use this pin to compensate the control loop.
BOOST (Pin 6):
The BOOST pin is used to provide a drive
VADJ (Pin 13):
The VADJ pin is the input to the internal voltage, higher than the input voltage, to the internal bipolar voltage to current amplifi er. Connect the VADJ pin to the NPN power switch. REF pin for a 1A output current. For lower output cur-
BIAS (Pin 7):
The BIAS pin connects through a Schottky rents, program the VADJ pin using the following formula: diode to BOOST. Tie to OUT. ILED = 1A • VADJ/1.25V.
GND (Pins 8, 15, Exposed Pad Pin 17):
Ground. Tie both
PWM (Pin 14):
The PWM pin controls the connection of GND pins and the Exposed Pad directly to the ground the VC pin to the internal circuitry. When the PWM pin is plane. The Exposed Pad metal of the package provides both low, the VC pin is disconnected from the internal circuitry electrical contact to ground and good thermal contact to and draws minimal current. If the PWM feature is unused, the printed circuit board. It must be soldered to the circuit leave this pin unconnected. board for proper operation.
RT (Pin 9):
The RT pin is used to set the internal oscilla- tor frequency. Tie an 80.6k resistor from RT to GND for a 500kHz switching frequency. 3474fd 6
PIN FUNCTIONS DNC (Pins 1, 16):
Do not connect external circuitry to these
SHDN (Pin 10):
The SHDN pin is used to shut down the pins, or tie them to GND. Leave the DNC pins fl oating. switching regulator and the internal bias circuits. The 2.6V switching threshold can function as an accurate
OUT (Pin 2):
The OUT pin is the input to the current sense under-voltage lockout. Pull below 0.3V to shut down the resistor. Connect this pin to the inductor and the output LT3474/LT3474-1. Pull above 2.65V to enable the LT3474/ capacitor. LT3474-1. Tie to VIN if the SHDN function is unused.
LED (Pin 3):
The LED pin is the output of the current sense
REF (Pin 11):
The REF pin is the buffered output of the resistor. Connect the anode of the LED here. internal reference. Either tie the REF pin to the VADJ pin for
VIN (Pin 4):
The VIN pin supplies current to the internal a 1A output current, or use a resistor divider to generate a circuitry and to the internal power switch and must be lower voltage at the VADJ pin. Leave this pin unconnected locally bypassed. if unused.
SW (Pin 5):
The SW pin is the output of the internal power
VC (Pin 12):
The Vc pin is the output of the internal error switch. Connect this pin to the inductor and switching amp. The voltage on this pin controls the peak switch diode. current. Use this pin to compensate the control loop.
BOOST (Pin 6):
The BOOST pin is used to provide a drive
VADJ (Pin 13):
The VADJ pin is the input to the internal voltage, higher than the input voltage, to the internal bipolar voltage to current amplifi er. Connect the VADJ pin to the NPN power switch. REF pin for a 1A output current. For lower output cur-
BIAS (Pin 7):
The BIAS pin connects through a Schottky rents, program the VADJ pin using the following formula: diode to BOOST. Tie to OUT. ILED = 1A • VADJ/1.25V.
GND (Pins 8, 15, Exposed Pad Pin 17):
Ground. Tie both
PWM (Pin 14):
The PWM pin controls the connection of GND pins and the Exposed Pad directly to the ground the VC pin to the internal circuitry. When the PWM pin is plane. The Exposed Pad metal of the package provides both low, the VC pin is disconnected from the internal circuitry electrical contact to ground and good thermal contact to and draws minimal current. If the PWM feature is unused, the printed circuit board. It must be soldered to the circuit leave this pin unconnected. board for proper operation.
RT (Pin 9):
The RT pin is used to set the internal oscilla- tor frequency. Tie an 80.6k resistor from RT to GND for a 500kHz switching frequency. 3474fd 6
