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PDF ADP8870 Data sheet ( Hoja de datos )
| Número de pieza | ADP8870 | |
| Descripción | Parallel Backlight Driver | |
| Fabricantes | Analog Devices | |
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Data Sheet
Charge-Pump, Parallel Backlight Driver
with Image Content PWM Input
ADP8870
FEATURES
Charge pump with automatic gain selection of 1×, 1.5×, and
2× for maximum efficiency
Two high accuracy (±5%) phototransistor inputs for
automated ambient light sensing (ALS)
5 programmable ambient light-sensing zones for optimal
backlight power savings
Independent ALS control of D7, for automated response of
keypad lighting to ambient light levels
PWM input can be used for content adaptive brightness
control (CABC) of any, or all, of the LEDs
PWM input scales the LED output current
7 independent, programmable LED drivers
6 drivers capable of 30 mA (maximum)
1 driver capable of 60 mA (maximum)
Programmable maximum current limit (128 levels)
Standby mode for <1 µA current consumption
16 programmable fade-in and fade-out times (0.1 sec to 5.5 sec)
with choice of square or cubic rates
Fading override
I2C-compatible interface for all programming
Dedicated reset pin and built-in power-on reset (POR)
Short-circuit, overvoltage, and overtemperature protection
Internal soft start to limit inrush currents
Input-to-output isolation during faults or shutdown
Operates down to VIN = 2.5 V, with undervoltage lockout
(UVLO) at 2.0 V.
Available in a small, 2.15 mm × 2.36 mm × 0.6 mm wafer level
chip scale package (WLCSP) or a 4 mm × 4 mm × 0.75 mm
lead frame chip scale package (LFCSP)
APPLICATIONS
Mobile display backlighting
Mobile phone keypad backlighting
RGB LED lighting
LED indication
General backlighting of small format displays
TYPICAL OPERATING CIRCUIT
VOUT
VDD_ALS
OPTIONAL
PHOTOSENSOR
PHOTO-
SENSOR
0.1µF
D1 D2 D3 D4 D5 D6 D7 CMP_IN
0.1µF
VIN
1µF
VDDIO
VOUT
1µF
nRST
SDA
SCL
nINT
PWM
ADP8870
C1+
C1
C1– 1µF
C2+
C2
C2– 1µF
GND
Figure 1.
GENERAL DESCRIPTION
The ADP8870 combines a programmable backlight LED
charge-pump driver with automatic phototransistor control of
the brightness (LED current) and a PWM input to control the
scale of the output current. This combination allows significant
power savings because it automatically changes the current
intensity based on the sensed ambient lighting levels and the
display image content. It performs this function automatically,
eliminating the need for a processor to monitor the photo-
transistor. The light intensity thresholds are fully programmable
via the I2C interface.
The ADP8870 allows up to six LEDs to be independently driven up
to 30 mA (maximum). An additional seventh LED can be driven to
60 mA (maximum). All LEDs are individually programmable for
minimum/maximum current and fade-in/fade-out times through
an I2C interface. These LEDs can also be combined into groups
to reduce the processor instructions during fade-in and fade-out.
Driving these components is a two-capacitor charge pump
with gains of 1×, 1.5×, and 2×. This setup is capable of driving a
maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. A full
suite of safety features, including short-circuit, overvoltage, and
overtemperature protection, allows easy implementation of a
safe and robust design. Additionally, input inrush currents are
limited via an integrated soft start combined with controlled
input-to-output isolation.
Rev. B
Document Feedback
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 ©2012–2014 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
1 page  
Data Sheet
ADP8870
Parameter
Hold Time
Data
Start/Repeated Start
Bus-Free Time (Stop and Start
Conditions)
Rise Time (SCL and SDA)
Fall Time (SCL and SDA)
Pulse Width of Suppressed
Spike
Capacitive Load Per Bus Line
Symbol
tHD, DAT
tHD, STA
tBUF
tR
tF
tSP
CB
Test Conditions/Comments
Min Typ
0
0.6
1.3
20 + 0.1 CB
20 + 0.1 CB
0
Max
0.9
300
300
50
400
1 Matching is calculated by dividing the difference between the maximum and minimum current from the sum of the maximum and minimum.
2 VIL is a function of the VIN voltage. See Figure 19 in the Typical Performance Characteristics section for typical values over operating ranges.
3 VIH is a function of the VIN voltage. See Figure 19 in the Typical Performance Characteristics section for typical values over operating ranges.
Unit
μs
μs
μs
ns
ns
ns
pF
Timing Diagram
SDA
tLOW
tR tSU, DAT
tF tF
tHD, STA
SCL
S tHD, DAT
S = START CONDITION
Sr = REPEATED START CONDITION
P = STOP CONDITION
tHIGH
tSU, STA
Sr
Figure 2. I2C Interface Timing Diagram
tSP tR
tBUF
tSU, STO
P
S
Rev. B | Page 5 of 60
5 Page 
Data Sheet
T
CIN = 1µF, COUT = 1µF, C1 = 1µF, C2 = 1µF
VIN = 3.6V
IOUT = 120mA
VIN (AC-COUPLED) 50mV/DIV
1
VOUT (AC-COUPLED) 50mV/DIV
2
IIN (AC-COUPLED) 10mA/DIV
3
1µs/DIV
Figure 23. Typical Operating Waveforms, G = 1×
T
CIN = 1µF, COUT = 1µF, C1 = 1µF, C2 = 1µF
VIN = 3.0V
IOUT = 120mA
1
VIN (AC-COUPLED) 50mV/DIV
VOUT (AC-COUPLED) 50mV/DIV
2
IIN (AC-COUPLED) 10mA/DIV
3
1µs/DIV
Figure 24. Typical Operating Waveforms, G = 1.5×
ADP8870
T
CIN = 1µF, COUT = 1µF, C1 = 1µF, C2 = 1µF
VIN = 2.5V
IOUT = 120mA
1
VIN (AC-COUPLED) 50mV/DIV
VOUT (AC-COUPLED) 50mV/DIV
2
IIN (AC-COUPLED) 10mA/DIV
3
1µs/DIV
Figure 25. Typical Operating Waveforms, G = 2×
T
CIN = 10µF, COUT = 1µF, C1 = 1µF, C2 = 1µF
VIN = 3.6V
VOUT (1V/DIV)
2
IIN (10mA/DIV)
IOUT (10mA/DIV)
3
4
100µs/DIV
Figure 26. Typical Start-Up Waveforms
Rev. B | Page 11 of 60
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ADP8870.PDF ] | |
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