Datasheet

LT3761
21
3761f
applicaTions inFormaTion
C
SS
M1
GND
PGND
AGND
V
IN
C
IN
L1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
4
3
3
2
1
5
6
1
2
R
SENSE
7
8
R
DIM
C
C
CTRL
DIM
V
REF
R
C
V
OUT
VIA
VIAS TO GROUND PLANES
LAYER 2
GROUND
PLANE
SPLIT
OPENLED
x
x
R
T
R2
R1
R3
R4
R
LED
3761 F07
LED
+
LED
–
M2
C
OUT
C
OUT
D1
COMPONENT DESIGNATIONS REFER TO BOOST LED DRIVER FOR AUTOMOTIVE HEADLAMP SCHEMATIC
CV
CC
C
PWM
PGND
AGND
SENSE VIA
x x
Figure 7. Suggested Layout of the Boost LED Driver for Automotive Headlamp in the Typical Applications Section
The ground terminal of the switch current sense resistor
should Kelvin connect to the GND of the LT3761. Likewise,
the ground terminal of the bypass capacitor for the INTV
CC
regulator should be placed near the GND of the switching
path. Typically this requirement will result in the external
switch being closest to the IC, along with the INTV
CC
bypass
capacitor. The ground for the compensation network (V
C
)
and other DC control signals (e.g., FB, PWM, DIM/SS, CTRL)
should be star connected to the underside of the IC. Do
not extensively route high impedance signals such as FB
and V
C
, as they may pick up switching noise. In particular,
avoid routing FB and PWMOUT in parallel for more than
a few millimeters on the board. Minimize resistance in
series with the SENSE input to avoid changes (most likely
reduction) to the switch current limit threshold.