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PDF ADP5501 Data sheet ( Hoja de datos )
| Número de pieza | ADP5501 | |
| Descripción | Programmable Current Backlight Driver | |
| Fabricantes | Analog Devices | |
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Programmable Current Backlight Driver
with Ambient Light Sensor Input
ADP5501
FEATURES
Efficient asynchronous boost converter for driving up to
6 white LEDs
2.7 V to 5.5 V input voltage range
128 programmable backlight LED current levels (30 mA
maximum)
Programmable backlight fade-in/fade-out times
Programmable backlight dim and off times
Ambient light sensing with autonomous backlight
adjustment
3 auxiliary LED current sinks
64 programmable auxiliary LED current levels (14 mA
maximum)
Programmable auxiliary LED fade-in/fade-out times
Programmable auxiliary LED on and off times (allows
blinking)
I2C-compatible serial interface
Interrupt line for signaling an external processor (INT)
Hard reset (RST)
Current limit protection
Thermal overload protection
Available in small 4.0 mm × 4.0 mm, 24-lead LFCSP package
APPLICATIONS
Display backlight driver with ambient light sensor input and
control and multiple LED indicator sinks
TYPICAL OPERATING CIRCUIT
2.7V TO 5.5V
1µF
I/O RAIL
1µF 4.7µH
2
1 PGND SW
21 VBAT
22
BST
23
BL_SNK
CAP_OUT 20
16 VDDIO
5 SCL
4 SDA
3 INT
15 RST
ADP5501
GND 19
GND 18
GND 24
CMP_IN 17
RGB
NC NC NC NC NC NC
6 7 8 9 10 11
LED1 LED2 LED0
12 13 14
1µF
100nF
VBAT
Figure 1.
3.3V
GENERAL DESCRIPTION
The ADP5501 is a versatile, single-chip, white LED backlight
driver with programmable ambient light sensor input and
programmable LED current. This device is designed for media-
enabled handset applications. The ADP5501 uses an I2C®-
compatible serial interface and a single line interrupt to
communicate with the host processor.
The ADP5501 can detect ambient light levels and adjust the
backlight brightness accordingly, resulting in extended battery life.
Once configured, the ADP5501 is capable of controlling the
display backlight intensity, on/off timing, dimming, and fading
without the intervention of the main processor, which translates
into valuable battery power savings. The three auxiliary LEDs
are also capable of fading and are timed on and off via register
programming.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2008 Analog Devices, Inc. All rights reserved.
1 page  
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ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Rating
VBAT to GND
VDDIO to GND
SW/BST to GND
LED0/LED1/LED2/CMP_IN/SCL/SDA/INT/
RST/CAP_OUT/BL_SNK to GND
–0.3 V to +6 V
–0.3 V to VBAT
–0.3 V to +30 V
–0.3 V to +6 V
PGND to GND
Operating Ambient Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
Soldering Conditions
–0.3 V to +0.3 V
−40°C to +85°C1
–40°C to +125°C
–65°C to +150°C
JEDEC J-STD-020
1 In applications where high power dissipation and poor thermal resistance
are present, the maximum ambient temperature may have to be derated.
Maximum ambient temperature (TA(MAX)) is dependent on the maximum
operating junction temperature (TJ(MAXOP) = 125°C), the maximum power
dissipation of the device (PD(MAX)), and the junction-to-ambient thermal
resistance of the part/package in the application (θJA), using the following
equation: TA(MAX) = TJ(MAXOP) – (θJA x PD(MAX)).
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ADP5501
Absolute maximum ratings apply individually only, not in
combination. Unless otherwise specified, all other voltages are
referenced to GND.
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3. Thermal Resistance
Package Type
24-Lead LFCSP_VQ
θJA
50
Unit
⁰C/W
ESD CAUTION
Rev. 0 | Page 5 of 28
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BACKLIGHT
CURRENT
MAX
DIM
ADP5501
program the off timer before turning on the backlight. If
BL_EN = 1, the backlight turns on to its maximum setting, and
the off timer starts counting. When the off timer expires, the
internal state machine clears the BL_EN bit, and the backlight
turns off.
BACKLIGHT
CURRENT
OFF TIMER
RUNNING
MAX
BL_EN = 1 DIM_EN = 1 DIM_EN = 0 BL_EN = 0
Figure 18. Backlight Turn-On/Turn-Off/Dim
The maximum and dim settings can be set between 0 mA and
30 mA; therefore, it is possible to program a dim setting that is
greater than a maximum setting. For normal expected opera-
tion, the user should program the dim setting to less than the
maximum setting.
AUTOMATIC DIM AND TURN-OFF TIMERS
The user can program the backlight to dim automatically by
using the BL_DIMT timer in Register 0x03. The dim timer has
15 settings ranging from 10 sec to 2 min. The user should
program the dim timer before turning on the backlight. If
BL_EN = 1, the backlight turns on to its maximum setting, and
the dim timer starts counting. When the dim timer expires, the
internal state machine sets DIM_EN = 1, and the backlight goes
to its dim setting.
BACKLIGHT
CURRENT
DIM TIMER
RUNNING
DIM TIMER
RUNNING
MAX
BL_EN = 1 BL_EN = 0
SET BY USER
SET BY INTERNAL STATE MACHINE
Figure 20. Off Time
Reasserting BL_EN at any point during the off timer count-
down causes the timer to reset and begin counting again. The
backlight can be turned off at any point during the off timer
countdown by clearing BL_EN.
The dim timer and off timer can be used together for sequential
maximum-to-dim-to-off functionality. With both the dim and
off timers programmed, if BL_EN is asserted, the backlight
turns on to its maximum setting. When the dim timer expires,
the backlight changes to its dim setting. When the off timer
expires, the backlight turns off.
BACKLIGHT
CURRENT
DIM TIMER
RUNNING
MAX
DIM OFF TIMER
RUNNING
DIM
BL_EN = 1 DIM_EN = 1 DIM_EN = 0 DIM_EN = 1
OR
SET BY USER
BL_EN = 1
SET BY INTERNAL STATEMACHINE
BL_EN = 0
Figure 19. Dim Timer
If the user clears the DIM_EN bit (or reasserts the BL_EN bit),
the backlight reverts to its maximum setting, and the dim timer
begins counting again. When the dim timer expires, the internal
state machine again sets DIM_EN = 1, and the backlight goes to
its dim setting. Reasserting BL_EN at any point during the dim
timer countdown causes the timer to reset and begin counting
again. The backlight can be turned off at any point during the
dim timer countdown by clearing BL_EN.
The user can also program the backlight to turn off automatic-
ally by using the BL_OFFT timer in Register 0x03. The off timer
has 15 settings ranging from 10 sec to 2 min. The user should
BL_EN = 1 DIM_EN = 1
SET BY USER
SET BY INTERNAL STATE MACHINE
BL_EN = 0
Figure 21. Dim and Off Timers Used Together
LINEAR BACKLIGHT FADE-IN AND FADE-OUT
To counteract the abrupt effect on the eyes of near instant turn-
on and turn-off of the backlight, the ADP5501 contains timers
to facilitate smooth fading among the off, on, and dim states. By
default (BL_LAW = 00 in Register 0x02), the ADP5501
implements a fading scheme using the linear backlight code
algorithm (see Equation 1).
Rev. 0 | Page 11 of 28
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet ADP5501.PDF ] | |
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