Datasheet

PGND AGND
COMP
SS
FB
C
IN
C
S
L = 4.7 éH
R
C
C
C
R
T
R
F
Battery or
Power Source
Pull high for TORCH
Pull high for FLASH
VIN SW
VOUT
EN
C
OUT
LM4510
50Ö
12.4Ö
10 éF
4.7 éF
10 nF
46.6k
2.2 nF
Everlight
47-23UWD/TR8
=I
Torch
]A[
V
FB
R
T
]A[
=I
Flash
V
FB
R//R
FT
LM4510
SNVS533C –SEPTEMBER 2007–REVISED MAY 2013 www.ti.com
3. All voltage-sensing resistors (R
F1
, R
F2
) should be kept close to the FB pin to minimize copper trace
connections that can inject noise into the system. The ground connection for the voltage-sensing resistor
should be connected directly to the AGND pin.
4. Trace connections made to the inductor should be minimized to reduce power dissipation, EMI radiation and
increase overall efficiency. Also poor trace connection increases the ripple of SW.
5. C
S
, C
C1
, C
C2
, R
C
must be placed close to the device and connected to AGND.
6. The AGND pin should connect directly to the ground. Not connecting the AGND pin directly, as close to the
chip as possible, may affect the performance of the LM4510 and limit its current driving capability. AGND
and PGND should be separate planes and should be connected at a single point.
7. For better thermal performance, DAP should be connected to ground, but cannot be used as the primary
ground connection. The PC board land may be modified to a "dog bone" shape to reduce SON thermal
impedance. For detail information, refer to Application Note AN-1187.
FLASH/TORCH APPLICATION
LM4510 can be configured to drive white LEDs for the flash and torch functions. The flash/torch can be set up
with the circuit shown in Figure 29 by using the resistor R
T
to determine the current in Torch Mode and R
F
to
determine the current in Flash Mode. The amount of current can be estimated using the following equations:
(11)
Figure 29. Flash/Torch Circuit Using LM4510
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