MAX8607 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX8607 Datasheet PDF : 10 Pages
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1MHz PWM Boost Converter for 1.5A
White LED Camera Flash
INPUT
L1
2.7V TO 5.5V 2.2µH
11, 12
LX
13
MAX8607 OUT
C1
U1
14
10µF
9, 10
OUTS
PGND
C3
0.1µF 1
COMP
7
LGND
MODE-
SELECT
INPUTS
2
EN1
3
EN2
FLSH
5
R1
GND 6
LED 8
MOV EP
4
R2
C2
10µF
D1
Figure 2. Typical Application Circuit
Inductor Selection
The MAX8607 is designed to use a 2.2µH inductor. To
prevent core saturation, ensure that the inductor-satura-
tion current rating exceeds the peak inductor current
for the application. Calculate the worst-case peak
inductor current with the following formula:
IPEAK
=
5V × ILED(MAX)
0.9 × VIN(MIN)
+
VIN(MIN) × 0.5µs
2 × 2.2µH
Table 2 provides a list of suggested inductors.
Capacitor Selection
Bypass the input to PGND using a ceramic capacitor.
Place the capacitor as close to the IC as possible. The
exact value of the input capacitor is not critical. The
typical value for the input capacitor is 10µF; however,
larger value capacitors can be used to reduce input
ripple at the expense of size and higher cost.
The output capacitance required depends on the
required LED current. A 10µF ceramic capacitor works
well in most situations, but a 4.7µF capacitor is accept-
able for load current below 300mA.
PC Board Layout
Due to fast switching waveforms and high-current paths,
careful PC board layout is required. Connect GND
directly to the exposed paddle underneath the IC; con-
nect the exposed paddle to the PC board ground plane.
Connect LGND and PGND to the ground plane. The out-
put bypass capacitor should be placed as close to the
IC as possible. CCOMP should be connected from
COMP to GND as close to the IC as possible. Minimize
trace lengths between the IC and the inductor, the input
capacitor, and the output capacitor; keep these traces
short, direct, and wide. The ground connections of CIN
and COUT should be as close together as possible and
connected to PGND. The traces from the input to the
inductor and from the output capacitor to the LED may
be longer. A sample layout is available in the MAX8607
evaluation kit (MAX8607EVKIT) to speed design.
Chip Information
PROCESS: BiCMOS
Table 2. Suggested Inductors
MANUFACTURER
Coilcraft
Cooper (Coiltronics)
FDK
TOKO
SERIES
LPO3310
SD3114
MIPF2520
MIPW3226
DE2812C
FDSE0312
INDUCTANCE
(µH)
2.2
2.2
2.2
2.2
2.2
2.2
DCR
(mΩ)
150
83
80
100
70
160
ISAT
(A)
1.1
1.48
0.7
1.1
1.6
2.3
DIMENSIONS
(LTYP x WTYP x HMAX = Volume)
3.3 x 3.3 x 1.0 = 11mm3
3.0 x 3.0 x 1.45 = 13mm3
2.5 x 2.0 x 1.0 = 5mm3
3.2 x 2.6 x 1.0 = 8mm3
3.0 x 2.8 x 1.2 = 10mm3
3.0 x 3.0 x 1.2 = 11mm3
8 _______________________________________________________________________________________
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