lt3475efe-trpbf Linear Technology Corporation, lt3475efe-trpbf Datasheet - Page 6

• Manufacturer Part Number: lt3475efe-trpbf
• Description: Dual Step-down 1.5a Led Driver
• Manufacturer: Linear Technology Corporation

LT3475/LT3475-1
PI FU CTIO S
R
oscillator frequency. Tie a 24.3k resistor from R
for a 600kHz switching frequency.
SHDN (Pin 16): The SHDN pin is used to shut down the
switching regulator and the internal bias circuits. The
2.6V switching threshold can function as an accurate
undervoltage lockout. Pull below 0.3V to shut down the
LT3475/LT3475-1. Pull above 2.6V to enable the LT3475/
LT3475-1. Tie to V
REF (Pin 17): The REF pin is the buffered output of the
internal reference. Either tie the REF pin to the V
for a 1.5A output current, or use a resistor divider to
generate a lower voltage at the V
unconnected if unused.
BLOCK DIAGRAM
6
T
U
(Pin 14): The R
C
OUT1
D1
L1
D
U
LED1
C
D3
C1
BOOST1
PWM 1
C1
OUT1
LED1
SW1
V
C1
IN
Q1
U
if the SHDN function is unused.
DRIVER
0.067Ω
T
gm1
pin is used to set the internal
100Ω
Q3
1.25k
Q
Q
ADJ
R
S
pin. Leave this pin
C1
V
IN
C
IN
∑
V
ADJ1
FREQUENCY
SLOPE COMP
FOLDBACK
T
V
to GND
IN
–
+
ADJ
INT REG
UVLO
AND
SLAVE
OSC
SHDN
MOSC 1
pin
2V
REF
MOSC 2
V
internal error amp. The voltage on this pin controls the
peak switch current. Use this pin to compensate the
control loop.
V
the internal voltage-to-current amplifi er. Connect the V
pin to the REF pin for a 1.5A output current. For lower
output currents, program the V
formula: I
PWM1, PWM2 (Pins 20, 11): The PWM pin controls the
connection of the V
the PWM pin is low, the V
internal circuitry and draws minimal current. If the PWM
feature is unused, leave this pin unconnected.
R
T
2V
ADJ1
SLAVE
C1
MASTER
OSC
OSC
SLOPE COMP
, V
FREQUENCY
FOLDBACK
R
T
, V
–
+
C2
1.25V
V
ADJ2
IN
(Pins 18, 13): The V
LED
∑
V
ADJ2
(Pins 19, 12): The V
= 1.5A • V
EXPOSED
C2
PAD
R
S
C
Q
Q
pin to the internal circuitry. When
ADJ
GND
C
100Ω
/1.25V.
Q4
pin is disconnected from the
1.25k
ADJ
C
DRIVER
0.067Ω
gm2
pin is the output of the
pin using the following
ADJ
Q2
pin is the input to
BOOST2
LED2
SW2
V
PWM2
OUT2
C2
D4
D
LED 2
C
C2
C2
C
L2
D2
OUT2
3475 BD
3475fb
ADJ