al8807 Diodes, Inc., al8807 Datasheet - Page 10

• Manufacturer Part Number: al8807
• Description: High Efficiency Low Emi 30v 1a Buck Led Driver
• Manufacturer: Diodes, Inc.

Applicatio
PWM Dimmi
LED current ca
pin to turn the
signal. In part
to a value belo
lower than 50
accuracy.
Typically, for a
Zooming in at
The accuracy
AL8807. For b
reduced.
The CTRL pin
output or push
AL8807
Document Numbe
ons Informa
70
60
50
40
30
20
10
e device on an
h pull output sta
00Hz, however
a PWM frequen
ing
00
00
00
00
00
00
00
ow the nomina
an be adjusted
icular, a PWM
of the low duty
r: DS35281 Rev. 3
duty cycles be
est accuracy/re
is designed to
0
0%
10%
%
y cycle dimming
ncy of 500Hz th
al average valu
age.
d digitally, by a
3 - 2
ation
r higher dimm
esolution the s
d off. This wi
low 10% show
signal with a m
be driven by b
20%
(cont.
Fig.
ws:
max resolution
applying a low
he accuracy is
both 3.3V and 5
ue set by resis
g is affected by
.)
ll produce an a
witching freque
ing frequencie
32 Low Duty
30%
HIGH E
Fig. 31 P
40%
ww
PWM Dimmin
stor R
y both the PWM
es can be use
P
PWM dimming
ww.diodes.com
%
ency should be
5V logic levels
FFICIENCY
average outpu
y Cycle PWM
of 10bit can be
better than 1%
frequency Pul
10 of 20
SET
50%
. To a
% for PWM rang
g [%]
M Dimming a
M frequency an
e applied to the
ng at 500Hz
e increased wh
Y LOW EM
achieve this re
ed, at the exp
se Width Mod
t current propo
directly from a
60%
MI 30V 1A B
70
at 300Hz
e CTRL pin to c
pense of dimm
nd also the swit
0%
ging from 1% to
ortional to the
ulated (PWM)
solution the PW
ile the PWM fre
logic output w
80%
BUCK LED
with either an op
ming dynamic
change the outp
o 100%.
tching frequenc
WM frequency
equency shoul
logic signal to
duty cycle of t
90%
AL
© Diodes
Nove
L8807
10
y has to be
00%
cy of the
pen drain
the control
put current
range and
mber 2011
s Incorporated
d be
DRIVER
the CTRL