MAX16834 Maxim Integrated Products, MAX16834 Datasheet - Page 13

• Manufacturer Part Number: MAX16834
• Description: High-Power LED Driver
• Manufacturer: Maxim Integrated Products

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Figure 3. Buck-Boost LED Driver (V
ESR and the bulk capacitance are equal, allowing 50%
of the ripple for the bulk capacitance. The capacitance
is given by:
where I
hertz, and ∆V
of allowable ripple is for the ESR of the output capaci-
tor. Based on this, the ESR of the output capacitor is
given by:
where IL
High-Power LED Driver with Integrated High-Side LED
Current Sense and PWM Dimming MOSFET Driver
V
IN
LED
P
is the peak inductor current in amperes.
R1
R2
is in amperes, C
C
ESR
OUTRIPPLE
OUT
COUT
______________________________________________________________________________________
C1
≥
∆
V
I
LED
<
OUTRIPPLE
is in volts. The remaining 50%
∆
V
× ×
OUTRIPPLE
R3
C4
R5
OUT
C2
C5
2
(
IL
LED+
P
D
is in farads, f
×
MAX
×
< 28V)
) 2
R6
f
SW
( )
Ω
FLT
LV
IN
UVEN
SC
RT/SYNC
V
REF
REFI
SGND
CC
MAX16834
SW
is in
PWMDIM
SENSE+
DIMOUT
COMP
NDRV
PGND
OVP+
CLV
HV
CS
Use the below equation to calculate the RMS current
rating of the output capacitor:
The input filter capacitor bypasses the ripple current
drawn by the converter and reduces the amplitude of
high-frequency current conducted to the input supply.
The ESR, ESL, and the bulk capacitance of the input
capacitor contribute to the input ripple. Use a low-ESR
input capacitor that can handle the maximum input
RMS ripple current from the converter.
For the boost configuration, the input current is the
same as the inductor current. For buck-boost
I
COUT(RMS)
ON
R7
C7
OFF
Q1
C6
=
L1
R8
(IL
+
D1
(
IL
C3
AVG
A
V V G
×
×
(1 D
D
-
MAX
R4
R9
Q2
MAX
Input Capacitor
)
2
))
×
R10
2
(
1 -
×
LED+
LED-
V
D
D
IN
MAX
MAX
LEDs
)
13