Datasheet LT3592 (Analog Devices) - 7
| Hersteller | Analog Devices |
| Beschreibung | 500mA Wide Input Voltage Range Step-Down LED Driver with 10:1 Dimming |
| Seiten / Seite | 24 / 7 — PIN FUNCTIONS. RT (Pin 1):. BRIGHT (Pin 2):. CAP (Pin 8):. SHDN (Pin 3):. … |
| Dateiformat / Größe | PDF / 323 Kb |
| Dokumentensprache | Englisch |
PIN FUNCTIONS. RT (Pin 1):. BRIGHT (Pin 2):. CAP (Pin 8):. SHDN (Pin 3):. OUT (Pin 9):. VIN (Pin 4):. VFB (Pin 10):. DA (Pin 5):
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LT3592
PIN FUNCTIONS RT (Pin 1):
Programs the frequency of the internal oscillator. capacitor. An internal Schottky is provided for the boost Connect a resistor from RT to ground. Refer to Table 1 or function and an external diode is not needed. An external the Typical Performance Characteristics for resistor values Schottky diode should be connected between BOOST and that result in desired oscillator frequencies. CAP for single LED applications or whenever a higher BOOST voltage is desired.
BRIGHT (Pin 2):
Used to program a 10:1 dimming ratio for the LED current. Drive this pin above 1.4V to command
CAP (Pin 8):
Output of the step-down converter and also maximum intensity or below 0.3V to command minimum an input to the LED current sense amplifi er. Connect the intensity. This pin can be PWMed at 150Hz for brightness fi lter capacitor, inductor, and the top of the external LED control between the 1x and 10x current levels. current sense resistor to this pin.
SHDN (Pin 3):
Used to shutdown the switching regulator
OUT (Pin 9):
Drives the LED or LEDs and is the other and the internal bias circuits. This pin can be PWMed at input to the LED current sense amplifi er. Connect this pin 150Hz for brightness control. to the anode of the top LED in the string, the bottom of the external LED current sense resistor, and the top of the
VIN (Pin 4):
Supplies current to the LT3592’s internal cir- V cuitry and to the internal power switches. Must be locally FB resistor divider. bypassed. For automotive applications, a pi network with a
VFB (Pin 10):
The feedback node for the output voltage cap from VIN to GND, a series inductor connected between control loop. Tie this node to a resistor divider between OUT VIN and the power source, and another cap from the far and GND to set the maximum output voltage of the step- end of the inductor to GND is recommended. down converter according to the following formula:
DA (Pin 5):
Allows the external catch diode current to be R1+ R2 V sensed to prevent current runaway, such as when V OUT = 1.21• IN is R2 high and the duty cycle is very low. Connect this pin to the anode of the external catch Schottky diode. where R1 connects between OUT and VFB and R2 connects between V
SW (Pin 6):
The SW pin is the output of the internal power FB and GND. switch. Connect this pin to the inductor and the cathode
Exposed Pad (Pin 11):
Ground. The underside exposed of the switching diode. pad metal of the package provides both electrical contact to ground and good thermal contact to the printed circuit
BOOST (Pin 7):
Provides a drive voltage, higher than the board. The device must be soldered to the circuit board input voltage to the internal bipolar NPN power switch. for proper operation. BOOST will normally be tied to the SW pin through a 0.1μF 3592fc 7
PIN FUNCTIONS RT (Pin 1):
Programs the frequency of the internal oscillator. capacitor. An internal Schottky is provided for the boost Connect a resistor from RT to ground. Refer to Table 1 or function and an external diode is not needed. An external the Typical Performance Characteristics for resistor values Schottky diode should be connected between BOOST and that result in desired oscillator frequencies. CAP for single LED applications or whenever a higher BOOST voltage is desired.
BRIGHT (Pin 2):
Used to program a 10:1 dimming ratio for the LED current. Drive this pin above 1.4V to command
CAP (Pin 8):
Output of the step-down converter and also maximum intensity or below 0.3V to command minimum an input to the LED current sense amplifi er. Connect the intensity. This pin can be PWMed at 150Hz for brightness fi lter capacitor, inductor, and the top of the external LED control between the 1x and 10x current levels. current sense resistor to this pin.
SHDN (Pin 3):
Used to shutdown the switching regulator
OUT (Pin 9):
Drives the LED or LEDs and is the other and the internal bias circuits. This pin can be PWMed at input to the LED current sense amplifi er. Connect this pin 150Hz for brightness control. to the anode of the top LED in the string, the bottom of the external LED current sense resistor, and the top of the
VIN (Pin 4):
Supplies current to the LT3592’s internal cir- V cuitry and to the internal power switches. Must be locally FB resistor divider. bypassed. For automotive applications, a pi network with a
VFB (Pin 10):
The feedback node for the output voltage cap from VIN to GND, a series inductor connected between control loop. Tie this node to a resistor divider between OUT VIN and the power source, and another cap from the far and GND to set the maximum output voltage of the step- end of the inductor to GND is recommended. down converter according to the following formula:
DA (Pin 5):
Allows the external catch diode current to be R1+ R2 V sensed to prevent current runaway, such as when V OUT = 1.21• IN is R2 high and the duty cycle is very low. Connect this pin to the anode of the external catch Schottky diode. where R1 connects between OUT and VFB and R2 connects between V
SW (Pin 6):
The SW pin is the output of the internal power FB and GND. switch. Connect this pin to the inductor and the cathode
Exposed Pad (Pin 11):
Ground. The underside exposed of the switching diode. pad metal of the package provides both electrical contact to ground and good thermal contact to the printed circuit
BOOST (Pin 7):
Provides a drive voltage, higher than the board. The device must be soldered to the circuit board input voltage to the internal bipolar NPN power switch. for proper operation. BOOST will normally be tied to the SW pin through a 0.1μF 3592fc 7