BL8580/1
■
FEATURES
No external component required
PWM dimming control available
Low noise and EMI
LED sink current of 20mA
Independent current sink circuit for each LED
output
Versatile supply voltage range
Low standby current
High accuracy current match on each channel
■
DESCRIPTOIN
The BL8580/1 is a CMOS based
White/Blue LED driver with stand-alone
capability. The driver is primarily designed
for LED backlighting of LCD display
powered by Li-ion battery With its high
efficiency, low standby current and wide
range of input supply voltage, the BL8580/1
is suitable for applications such as portable
device display and keypad backlighting.
In
portable
application,
three
or
four-channel LED solutions are popular.
BL8580 has three LED channels with a
SOT-23-6 package. BL8581 has four LED
channels with a SOP-8 package.
■
APPLICATIONS
Small Size Color LCD Backlights Driver
Mobile Phone, Portable Device Keypad
Backlights Driver
■
TYPICAL APPLICATION
■
ORDERING INFORMATION
BL8580PRC
BL8581PS
SOT-23-6
SOP-8
3 Channel
4 Channel
Pb free
Pb free
3k/reel
2.5k/reel
-25~125°C
-25~125°C
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Total 7 Pages
BL8580/1
■
PIN DESCRIPTION
Pin Name
LED1-LEDn
EN
VCC
GND
Function
RGB or WLED cathode connection pin
Chip enable pin. High level activates the chip. Connect the
pin to VCC if not used, do not leave this pin floating
Power Supply
Analog ground. In BL8581, for good LED current match, it is
recommended that the two GND pins should be tied together by
external copper.
■
ABSOLUTE MAXIMUM RATING
Supply voltage range
Voltage
of LEDn,
EN pin
Maximum junction temperature
Storage temperature range
Lead temperature and time
-0.3V~7V
-0.3V~7V
-150℃
-40~150℃
-260℃, 10s
■
RECOMMENDED OPERATING CONDITION
PARAMETERS
Supply voltage
Output sink current on each channel
Operating free-air temperature range
MIN
2.7
-25
NOM
MAX
6
25
125
UNIT
V
mA
℃
■
ELECTRICAL CHARACTERISTICS
V
DD
=3.7V, T
a
=25°C, No Load, Input: V
IH
=3.7V, V
IL
=GND. (Unless otherwise noted)
Reference Data
Symbols
Parameters
Conditions
Unit
MIN TYP MAX
V
IL
V
IH
I
IL
I
IH
V
LEDL
I
LED
∆I
LEDn
I
Q
I
STBY
EN Pin “Low” Logic
EN Pin “High” Logic
EN Pin “Low” Input Current
EN Pin “High” Input Current
LEDn Dropout Voltage
LEDn Sink Current
LEDn Sink Current Deviation
Quiescent Current
Standby Supply Current
VEN=”1”
VEN=”0”
0.4
1.7
-1
1
V
V
µA
19
µA
100
mV
20
21
mA
+/-3 %
250 400
µA
0.5
µA
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Total 7 Pages
BL8580/1
■
DETAILED DESCRIPTION
BL8580/1 works with a wide range of
supply voltage, from 2.7V to 6V. The
forward voltage of commercial white/blue
LED is in the range of 2.9V to 3.5V at a
current level of 20mA. Proper selection of
the LED to match the supply voltage can
fully utilize the Li-ion battery. For example,
there is 1% ~ 3 % power left in the Li-ion
battery when its voltage reaches 3.275V.
So a LED with a forward voltage value of
3.2V can use up to 99% of the battery
power under normal working condition.
When the voltage of the battery drops
below 3.2V, the current through the LED
(hence the brightness) starts to decrease.
Due to its uniquely designed current
regulator, BL8580/1 offer low output
dropout and provide superior efficiency
performance over standard Inductive boost
type and capacitive charge pump type LED
driver.
The EN pin controls the on/off state of the
device. A high level state turns on the
device and a low level turns off the device,
results in the low off state current. This pin
needs to be terminated since a floating
level of the EN pin will cause the instability
of the device.
The sink current has a constant value of
20mA. The brightness of the LED can be
adjusted by controlling the duty cycle of the
BL8580/1’s LEDn output. This can be
accomplished by applying a PWM signal to
the EN pin. In BL8580/1, the internal power
on sequence presents a delay time of 6us
from CE pin to LEDn pin. Hence, In order to
normally modulate the output of LEDn in
every cycle, the width of dimming signal
applied CE pin have to be no less than 6us.
For example, when a dimming signal of
20KHz is applied, the minimum range of
dimming is about 12%, that is, the average
output current on each channel is 2.4 mA.
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Total 7 Pages
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