LT3477EUF#PBF Linear Technology, LT3477EUF#PBF Datasheet - Page 5

• Manufacturer Part Number: LT3477EUF#PBF
• Description: IC LED DRVR HP CONST CURR 20-QFN
• Manufacturer: Linear Technology
• Type: High Power, Constant Currentr

Specifications of LT3477EUF#PBF

• Constant Current: Yes
• Constant Voltage: Yes
• Topology: Flyback, PWM, SEPIC, Step-Down (Buck), Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: General Purpose
• Type - Secondary: White LED
• Frequency: 200kHz ~ 3.5MHz
• Voltage - Supply: 2.5 V ~ 25 V
• Mounting Type: Surface Mount
• Package / Case: 20-QFN
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: 3A
• Internal Switch(s): Yes
• Efficiency: 93%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Lead Free Status / Rohs Status: Compliant

TYPICAL PERFORMANCE CHARACTERISTICS
PIN FUNCTIONS
NC (Pins 1, 2, 20/Pins 18, 19, 20): No Connect Pin. Okay
to connect to ground or V
V
Powers the internal control circuitry.
R
ing frequency. Connect a 17.2k resistor between R
GND for a 1MHz switching frequency. Do not leave this pin
open. See Table 4 for additional R
frequencies.
SHDN (Pin 5/Pin 3): Shutdown. Tie to 2V or greater to
enable the device. Tie below 0.3V to turn off the device.
SS (Pin 6/Pin 4): Soft-Start. Place a soft-start capacitor
here. Leave fl oating if not in use.
V
Connect a series RC from this pin to GND. Typical values
are 1kΩ and 4.7nF.
FBN (Pin 8/Pin 6): The Inverting Input to the Error Ampli-
fi er. Connect resistive divider tap here for positive output
voltage.
IN
C
T
(Pin 4/Pin 2): Timing Resistor Pin. Adjusts the switch-
(Pin 7/Pin 5): Compensation Pin for Error Amplifi er.
(Pin 3/Pin 1): Input Supply. Must be locally bypassed.
104
103
102
101
100
98
99
97
96
–50
Current Sense Voltage
vs Temperature
–25
IN
(QFN/TSSOP)
0
TEMPERATURE (°C)
, or to fl oat.
V
V
25
CM
CM
= 10V
= 42V
T
50
values and switching
75
100
3477 G14
125
T
and
FBP (Pin 9/Pin 7): The Noninverting Input to the Error
Amplifi er. Connect resistive divider tap here for negative
output voltage.
V
nally set to 1.235V. Connect this pin to FBP if generat-
ing a positive output or to an external resistor divider if
generating a negative voltage. This pin can provide up
to 100μA of current and can be locally bypassed with a
100pF capacitor.
I
Setting I
the sensed voltage of the second current sense amplifi er
linearly. If I
current sense voltage is 100mV. If current sense amplifi er 2
is not used, always tie I
I
Setting I
of the sensed voltage of the fi rst current sense amplifi er
linearly. If I
current sense voltage is 100mV. If current sense amplifi er 1
is not used, always tie I
ADJ2
ADJ1
REF
(Pin 10/Pin 8): Bandgap Voltage Reference. Inter-
(Pin 11/Pin 9): Second Current Sense Adjustment.
(Pin 12/Pin 10): First Current Sense Adjustment.
ADJ2
ADJ1
120
100
ADJ2
ADJ1
80
60
20
40
0
to be less than 625mV leads to adjustment of
to be less than 625mV leads to adjustment
0
Current Sense Voltage vs I
V
CM
is tied to higher than 650mV, the default
is tied to higher than 650mV, the default
100
= 10V
200
I
ADJ
ADJ2
ADJ1
300
VOLTAGE (mV)
400
to higher than 650mV.
to higher than 650mV.
500
600
ADJ
700
2477 G13
LT3477
800
3477fc
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