Datasheet ADP5501 Datasheet (ANALOG DEVICES)

Programmable Current Backlight Driver

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)

2

I

C-compatible serial interface
Interrupt line for signaling an external processor (
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

INT

)

with Ambient Light Sensor Input

ADP5501

TYPICAL OPERATING CIRCUIT

2.7V TO 5.5V

I/O RAIL

10kΩ

1µF

1

21

16

10kΩ

2.2kΩ

2.2kΩ

5

4

3

15

1µF

4.7µH

2

SW22BST

PGND

VBAT

VDDIO

SCL

SDA

INT

RST

6NC7NC8NC9NC10NC11NC12

ADP5501

Figure 1.

LED1

BL_SNK

CAP_OUT

RGB

LED2

13

23

GND

GND

GND

CMP_IN

LED0

14

20

1µF

19

18

24

100nF

17

VBAT

3.3V

07780-001

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 media­enabled handset applications. The ADP5501 uses an I
compatible serial interface and a single line interrupt to
communicate with the host processor.

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.
Trademarks and registered trademarks are the property of their respective owners.

2

C®-

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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2008 Analog Devices, Inc. All rights reserved.

ADP5501

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1 

Typical Operating Circuit ................................................................ 1

General Description ......................................................................... 1

Revision History ............................................................................... 2

Specifications ..................................................................................... 3

Absolute Maximum Ratings ............................................................ 5

Thermal Resistance ...................................................................... 5

ESD Caution .................................................................................. 5

Pin Configuration and Function Descriptions ............................. 6

Typical Performance Characteristics ............................................. 7

Theory of Operation ........................................................................ 9

Backlight Drive Control .............................................................. 9

Backlight Operating Levels ....................................................... 10

Backlight Maximum and Dim Settings ................................... 10

Backlight Turn-On/Turn-Off/Dim .......................................... 10

Automatic Dim and Turn-Off Timers ..................................... 11

Linear Backlight Fade-In and Fade-Out .................................. 11

Fade Override ............................................................................. 13

Advanced Fading (Square) ........................................................ 13

Advanced Fading (Cubic 1 and Cubic 2) ................................ 13

Ambient Light Sensing .............................................................. 14

Automatic Backlight Adjustment ............................................. 14

LED Current Sinks ..................................................................... 15

Interrupt Output (

Reset Input (

Communicaton Interface .............................................................. 18

Register Map ................................................................................... 19

Detailed Register Descriptions ..................................................... 20

Applications Information .............................................................. 26

Converter Topology ................................................................... 26

PCB Layout ................................................................................. 27

Example Circuit .......................................................................... 27

Outline Dimensions ....................................................................... 28

Ordering Guide .......................................................................... 28

INT

) ............................................................. 17 

RST

) ....................................................................... 17

REVISION HISTORY

10/08—Revision 0: Initial Version

Rev. 0 | Page 2 of 28

ADP5501

SPECIFICATIONS

VBAT = 2.7 V to 5.5 V, TJ = −40C to +125C, unless otherwise noted.

Table 1.

Parameter Symbol Conditions1 Min Typ Max Unit

SUPPLY VOLTAGE

VBAT Input Voltage Range V
VDDIO Input Voltage Range VIO 1.8 3.3
Undervoltage Lockout Threshold UVLO
UVLO
UVLO
UVLO
SW Leakage SW

SUPPLY CURRENT

Shutdown Current3 I
Standby Current4 I

BACKLIGHT LED DRIVER (SW, BST)

Current Limit (Peak Inductor Current) 450 600 750 mA
On Resistance 200 200 400 mΩ
Overvoltage Threshold 24.5 27 29.5 V
Boost Startup Time 1 mS

BACKLIGHT LED CURRENT SINK (BL_SNK)

Full-Scale Current Sink

Backlight Current Ramp Rate Fade timers disabled 0.3 mA/ms

AMBIENT LIGHT SENSOR (CMP_IN)

Full-Scale Current BL

INPUT LOGIC LEVELS (SCL, SDA, RST)

Logic Low Input Voltage VIL 1.8 V ≤ VDDIO ≤ 3.3 V
Logic High Input Voltage VIH 1.8 V ≤ VDDIO ≤ 3.3 V

Input Leakage Current V
INPUT LOGIC DEBOUNCE (RST)
OPEN-DRAIN OUTPUT LOGIC LEVELS (INT, SDA)

Logic Low Output Voltage VOL I

Logic High Leakage Current V
AUX LED CURRENT SINKs (ILED, C3, R3)

Leakage LED

Full-Scale Current Sink LED
THERMAL SHUTDOWN

Thermal Shutdown Threshold TS TJ rising 150 °C

Thermal Shutdown Hysteresis TS
I2C TIMING SPECIFICATIONS

Delay from Reset Deassertion to I2C Access 60 s

SCL Clock Frequency f

SCL High Time t

SCL Low Time t

Data Setup Time t

Data Hold Time t

Setup Time for Repeated Start t

2.7 5.5 V

BAT

VBAT falling 1.7 2.1 V

VBAT

VBAT rising 2.4 2.7 V

VBAT

VDDIO falling 1.1 1.3 V

VDDIO

VDDIO rising 1.4 V

VDDIO

2.7 V ≤ VBAT ≤ 5.5 V 0.1 1 A

LEAKAGE

VDDIO = 0 V 0.1 1 A

SD

STNBY

1.8 V ≤ VDDIO ≤ 3.3 V
STNBY

= 0

Backlight code = 0x7F,

2

25 45 A

,

26 30 32 mA

2

V

bias = 0.65 V

0.7 1 1.2 mA

FULLSCALE

2

0.3 × VDDIO V

2

0.7 × VDDIO V

1.8 V ≤ VDDIO ≤ 3.3 V

I-LEAKAGE

2

0.1 1 µA

VIL-DBNC 50 75 100 s

= 1mA 0.4 V

OH-LEAKAGE

SINK

1.8 V ≤ VDDIO ≤ 3.3 V

2

0.1 1 µA

Sink disabled 0.1 1 µA

LEAKAGE

Applied pin voltage = 1 V 10.5 14 16.5 mA

FULLSCALE

T

HYS

400 kHz

SCL

0.6 s

HIGH

1.3 s

LOW

100 ns

SU, DAT

0 0.9 s

HD, DAT

0.6 s

SU, STA

falling 10 °C

J

Rev. 0 | Page 3 of 28

ADP5501

Parameter Symbol Conditions

Hold Time for Start/Repeated Start t
Bus Free Time for Stop and Start Condition t
Setup Time for Stop Condition t

0.6 s

HD, STA

1.3 s

BUF

0.6 s

SU, STO

1

Min Typ Max Unit

Rise Time for SCL and SDA tR 20 + 0.1 CB 300 ns
Fall Time for SCL and SDA tF 20 + 0.1 CB 300 ns
Pulse Width of Suppressed Spike tSP 0 50 s

5

Capacitive Load for Each Bus Line C

1

All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC). Typical values are at TA = 25°C, VBAT = 3.6 V.

2

3.3 V or VBAT, whichever is smaller.

3

Internal LDO powered down, digital blocks inactive, I2C inactive, boost inactive.

4

Internal LDO powered up, digital blocks active, I2C active, boost inactive.

5

C

is the total capacitance of one bus line in picofarads (pF).

B

B

400 pF

SDA

t

t

LOW

SCL

S

S = START CONDI TION
Sr = REPEATED START CONDITION
P = STOP CO NDITION

t

R

t

HD, DAT

t

SU, DAT

t

HIGH

t

F

t

SU, STA

t

F

t

HD, STA

Sr

t

SP

t

SU, STO

t

R

BUF

P S

07780-002

Figure 2. Interface Timing Diagram

Rev. 0 | Page 4 of 28

ADP5501

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

VBAT to GND –0.3 V to +6 V
VDDIO to GND –0.3 V to VBAT
SW/BST to GND –0.3 V to +30 V
LED0/LED1/LED2/CMP_IN/SCL/SDA/INT/

RST/CAP_OUT/BL_SNK to GND
PGND to GND –0.3 V to +0.3 V
Operating Ambient Temperature Range −40°C to +85°C
Operating Junction Temperature Range –40°C to +125°C
Storage Temperature Range –65°C to +150°C
Soldering Conditions 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)).

–0.3 V to +6 V

1

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.

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 θJA Unit

24-Lead LFCSP_VQ 50 ⁰C/W

ESD CAUTION

Rev. 0 | Page 5 of 28

ADP5501

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

VBAT

BST

BL_SNK

GND

CAP_OUT

GND

20

19

21

22

23

24

PIN 1
INDICATO R

1PGND
2SW
3
4SDA
5SCL
6NC

ADP5501

TOP VIEW

(Not to Scale)

9

7

8

C

C

C

N

N

N

INT

NOTES

1. NC = NO CONNECT .

2. EXPOSED P AD MUST BE CONNECT ED
TO GROUND.

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin No. Mnemonic Description

1 PGND Power Switch Output to Ground.
2 SW Power Switch Input.
3

Processor Interrupt, Active Low, Open Drain. INT should be pulled up to VDDIO.

INT
4 SDA I2C-Compatible Serial Data Line (Open Drain Requires External Pull-Up) to VDDIO.
5 SCL I2C-Compatible Serial Clock Line (Open Drain Requires External Pull-Up) to VDDIO.
6 NC No Connect.
7 NC No Connect.
8 NC No Connect.
9 NC No Connect.
10 NC No Connect.
11 NC No Connect.
12 LED1 LED 1 Current Sink. LED1 can be used with LED0 and LED2 as RGB.
13 LED2 LED 2 Current Sink. LED2 can be used with LED1 and LED0 as RGB.
14 LED0 LED 0 Current Sink. LED0 can be used with LED1 and LED2 as RGB.
15

Reset Input, Active Low. This input signal resets the device to the power-up default conditions. It must be driven

RST

low for a minimum of 75 s (typical) to be valid.

16 VDDIO

Supply Voltage for the I/O Pin. The output pin can be 1.8 V to 3.3 V or VBAT, whichever is smaller. If VDDIO = 0,

the device goes into full shutdown mode.
17 CMP_IN Input for Ambient Light Sensing.
18 GND Ground.
19 GND Ground.
20 CAP_OUT

Capacitor for Internal 2.7 V LDO. A 1 F capacitor must be connected between this pin and ground. Do not use

this pin to supply external loads.
21 VBAT Main Supply Voltage for the IC (2.7 V to 5.5 V).
22 BST Overvoltage Monitor Input for the Boost Converter.
23 BL_SNK Backlight Current Sink.
24 GND Ground.
EPAD The exposed pad must be connected to ground.

18 GND
17 CMP_IN
16 VDDI O
15

RST
14 LED0
13 LED2

11

12

10

1

C

C

N

N

LED

07780-003

Rev. 0 | Page 6 of 28

ADP5501

TYPICAL PERFORMANCE CHARACTERISTICS

VBAT = 3.6 V, TA = 25°C, unless otherwise noted. Inductor = LPS4012-472MLB. Schottky rectifier = MBR140SFT1G.

90

85

80

75

70

65

60

EFFICIE NCY (%)

55

50

45

40

024681012141618202224262830

BACKLIGHT CURRENT (mA)

6 LEDs, VBAT = 3. 0V
6 LEDs, VBAT = 3. 6V
6 LEDs, VBAT = 4. 2V
6 LEDs, VBAT = 5. 5V

Figure 4. Efficiency vs. Backlight Current (6 LEDs)

07780-004

48

40

TEMP = +25°C

32

24

16

8

STANDBY SUPPLY CURRENT (µA)

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

TEMP = –40°C

TEMP = +85°C

VBAT (V)

Figure 7. Standby Supply Current vs. VBAT

7780-007

90

85

80

75

70

65

60

EFFICIE NCY (%)

55

50

45

40

024681012141618202224262830

BACKLIGHT CURRENT (mA)

6 LEDs, VBAT = 3. 6V
5 LEDs, VBAT = 3. 6V
4 LEDs, VBAT = 3. 6V

Figure 5. Efficiency vs. Backlight Current (4, 5, and 6 LEDs)

90

85

80

75

70

65

60

EFFICIE NCY (%)

55

50

45

40

024681012141618202224262830

BACKLIGHT CURRENT (mA)

6 LEDs, VBAT = 4.2V
6 LEDs, VBAT = 4.2V,

AUTOLOAD-ENABLED

Figure 6. Efficiency vs. Backlight Current (Autoload On/Off)

16

14

12

10

8

6

4

2

AUX LED FULL -SCALE SINK CURRENT (mA)

0

0 0.5 1.0 1.5 2.0 2.5 3.0

07780-005

AUX LED PIN VO LTAGE (V )

07780-008

Figure 8. Typical Auxiliary LED Pin (LED0, LED1, LED2), Full-Scale

Sink Current vs. Applied Pin Voltage

07780-006

Rev. 0 | Page 7 of 28

ADP5501

SW

1

INDUCTOR CURRENT

2

BST

BL_SNK

3

4

CH1 20.0V

CH3 10.0V

CH2 500mA

CH4 1.0V

Figure 9. Boost Operation (Backlight = 30 mA)

SW

1

INDUCTOR CURRENT

2

BST

TIME (4µs/DIV)

SW

1

INDUCTOR CURRENT

2

BST

BL_SNK

3

0907780-0

4

CH1 20.0V

CH3 10.0V

CH2 500mA

CH4 1.0V

TIME (4µs/DIV)

07780-011

Figure 11. Boost Operation (Backlight = 2 mA)

SW

1

INDUCTOR CURRENT

2

BST

BL_SNK

3

4

CH1 20.0V

CH3 10.0V

CH2 500mA

CH4 1.0V

Figure 10. Boost Operation (Backlight = 15 mA)

TIME (4µs/DIV)

07780-010

3

4

BL_SNK

CH1 10.0V

CH3 10.0V

CH2 500mA

CH4 1.0V

TIME (1ms/DIV)

Figure 12. Boost Startup

07780-012

Rev. 0 | Page 8 of 28

ADP5501

2

V

THEORY OF OPERATION

.7V TO 5.5

1µF

4.7µH

1µF

PGND

VBAT

VDDIO

CAP_OUT

1µF

SCL

SDA

INT

RST

1

21

16

20

5

4

3

15

SW

2

EN

POR

BIAS/CLOCK

INTERFACE

GND19GND24GND

18

BOOST

CONTROL

IN

LDO

OUT

2.7V

6NC7NC8NC9NC10NC11

OVPI-LIMIT

ADP5501

Figure 13. Internal Block Diagram

The ADP5501 is an autonomous backlight white LED driver
with programmable current and ambient light sensor input. It is
ideal for cellular phone designs and other portable devices,
where programmable and automated light output is needed. Its
versatility makes it ideal for media-enabled mobile devices.
Programmable fade-in, fade-out, dim, and off timers provide
the backlight with excellent flexibility and control features.
Using an external photodiode, the ADP5501 can perform
ambient light sensing and adjust the backlight brightness
according to varying lighting conditions.

Programmable fading is also available for the three LED sinks.
Once programmed through its I
ADP5501 can run autonomously. An interrupt line (

2

C-compatible interface, the

INT

) is
available to alert an external microprocessor of the status of its
ambient light sensor comparator states, current limit, thermal
overload, and overvoltage conditions.

BACKLIGHT DRIVE CONTROL

White LEDs are common in backlighting the displays of
modern portable devices such as cell phones. White LEDs
require a high forward voltage, V
conduct current and emit light. Display panels, depending on
their size, can be backlit with single or multiple white LEDs. In
panels that require multiple LEDs, the LEDs are commonly
connected in a series string to achieve uniform brightness in
each LED by passing a common current through all of them.
The LED string, however, needs to be biased with a voltage
greater than the sum of each LED V

(typically, 3.5 V), before they

F

before it can conduct.

F

BST BL_SNK

22

27V

STATE MACHINE

REGISTER MAP

INTERRUPT/RESET

CONTROL

FB

NC

THERMAL

PROTECTION

0.65V

13

LED1

LED2

To achieve this high voltage, the ADP5501 contains a nonsyn­chronous boost device capable of driving an LED string with an
OVP limited to 24.5 V(minimum). For detailed information
about the boost device, see the Applications Information
section. With sufficient forward voltage created, the ADP5501
controls the current (and thus the brightness) of the LED string
via an adjustable internal current sink. An internal state
machine, in conjunction with programmable timers, dynamically
adjusts the current sink between 0 mA and 30 mA to achieve
impressive backlight control features.

DAYLIGHT_MAX

DAYLIGHT_DIM

OFFICE_MAX

OFFICE_DIM

DARK_MAX

DARK_DIM

BL_LVL

23

BACKLIGHT

CURRENT
CONTROL

LIGHT

SENSOR

LED
CURRENT
CONTRO L

14

12

LED0

MUX

17

BST

BL_OFFT

BL_DIMT

BL_FI

BL_FO

CMP_IN

Figure 14. Backlight Brightness Control

VBAT

100nF

BL_VALUE

COUNTERS

AND

CONTROL

LOGIC

07780-013

BL_SNK

BL_EN

DIM_EN

BL_LAW

CLOCK

GENERATOR

07780-014

Rev. 0 | Page 9 of 28

ADP5501

BACKLIGHT OPERATING LEVELS

Backlight brightness control can operate in three distinct levels:
daylight (L1), office (L2), and dark (L3). The BL_LVL bits in
Register 0x02 control the level at which the backlight operates.
The BL_LVL bits can be changed manually or, if in auto mode,
by the ambient light sensor (see the Ambient Light Sensing
section). By default, the backlight operates at daylight level
(BL_LVL = 00), where the maximum brightness is set using
Register 0x05 (DAYLIGHT_MAX). A daylight dim setting can
also be set using Register 0x06 (DAYLIGHT_DIM). When oper­ating at office level (BL_LVL = 01), the backlight maximum and
dim brightness settings are set by Register 0x07 (OFFICE_MAX)
and Register 0x08 (OFFICE_DIM). When operating at dark
level (BL_LVL = 10), the backlight maximum and dim
brightness settings are set by Register 0x09 (DARK_MAX) and
Register 0x0A (DARK_DIM).

DAYLIGHT (L1) OF FICE (L 2) DARK (L3)

30mA

DAYLIGHT_MAX

OFFICE_M AX

DARK_MAX

DAYLIGHT_DIM

BACKLIGHT CURRENT

0

BACKLIGHT O PERATING LEVELS

Figure 15. Backlight Operating Levels

BACKLIGHT MAXIMUM AND DIM SETTINGS

The backlight maximum and dim current settings are determined
by a 7-bit code programmed by the user into the registers listed
in the Backlight Operating Levels section. This 7-bit code allows
the user to set the backlight to one of 128 different levels between
0 mA and 30 mA. The ADP5501 can implement two distinct
algorithms to achieve a linear and a nonlinear relationship
between input code and backlight current. The BL_LAW bits, in
Register 0x02, are used to swap between algorithms.

By default, the ADP5501 uses a linear algorithm (BL_LAW = 00),
where the backlight current increases linearly for a corresponding
increase of input code. Backlight current, in milliamperes (mA),
is determined by the following equation:

Backlight Current = Code × (Fullscale_Current/127) (1)

where:

Code is the input code programmed by the user.
Fullscale_Current is the maximum sink current allowed

(typically, 30 mA).

OFFICE_DIM

DARK_DIM

The ADP5501 can also implement a nonlinear (square approx­imation) relationship between input code and backlight current
level. In this case (BL_LAW = 01), the backlight current, in milli­amperes (mA), is determined by the following equation:

2

⎞
⎟

(2)

⎟
⎠

Backlight Current =

⎛
⎜

Code

⎜
⎝

CurrentFullscale

×

_

127

Figure 16 shows the backlight current level vs. input code for
both the linear and square law algorithms.

30

25

20

15

10

BACKLIGHT CURRENT (mA)

5

0

0 32 64 96 128

LINEAR

SQUARE

SINK CODE

Figure 16. Backlight Current vs. Sink Code

07780-016

BACKLIGHT TURN-ON/TURN-OFF/DIM

07780-015

With the device in normal mode (set in Register 0x00 by
STNBY

= 1), the backlight can be turned on using the BL_EN
bit in Register 0x00. Before turning on the backlight, the user
should choose the level (daylight (L1), office (L2), or dark (L3))
to operate in and ensure that maximum and dim settings are
programmed for that level. The backlight turns on when
BL_EN = 1. The backlight turns off when BL_EN = 0.

BACKLIGHT

CURRENT

MAX

BL_EN = 1 BL _EN = 0

Figure 17. Backlight Turn-On/Turn-Off

7780-017

While the backlight is on (BL_EN = 1), the user can change it to
a dim setting by programming DIM_EN = 1 in Register 0x00. If
DIM_EN = 0, the backlight reverts to its maximum setting.

Rev. 0 | Page 10 of 28

ADP5501

BACKLIGHT

CURRENT

MAX

DIM

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

MAX

OFF TIMER

RUNNING

BL_EN = 1

DIM_EN = 1 DIM_EN = 0 BL_EN = 0

7780-018

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 opera­tion, 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

MAX

DIM TIME R

RUNNING

DIM TIMER

RUNNING

SET BY USER
SET BY INTERNAL STATE MACHINE

BL_EN = 1 BL_EN = 0

07780-020

Figure 20. Off Time

Reasserting BL_EN at any point during the off timer count­down 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

MAX

DIM TIMER

RUNNING

DIM

BL_EN = 1 BL_EN = 0DIM_EN = 1 DIM_EN = 0

SET BY USER
SET BY INTERNAL STATEMACHINE

BL_EN = 1

OR

DIM_EN = 1

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 automatic­ally 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

Rev. 0 | Page 11 of 28

OFF TIMER

RUNNING

DIM

7780-019

SET BY USER
SET BY INTERNAL STATE MACHINE

BL_EN = 1 BL_EN = 0DIM_EN = 1

07780-021

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 turn­on 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).

ADP5501

The BL_FI timer in Register 0x04 can be used for smooth fade­in transitions from low to high backlight settings such as off to
dim, off to maximum, and dim to maximum. The BL_FI timer
can be programmed to one of 15 settings ranging from 0.3 sec
to 5.5 sec. The BL_FI timer should be programmed before
asserting BL_EN.

30.0

27.5

25.0

22.5

20.0

17.5

15.0

12.5

10.0

7.5

BACKLIGHT CURRENT (mA)

5.0

2.5

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-IN TIME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-022

Figure 22. Linear Fade-In Times

The time programmed in BL_FI represents the time it takes the
backlight current to go from 0 mA to 30 mA. Fading between
intermediate settings is shorter.

The BL_FO timer in Register 0x04 can be used for smooth fade­out transitions from high to low backlight settings such as
maximum to dim and dim to off. The BL_FO timer can be
programmed to one of 15 settings ranging from 0.3 sec to 5.5 sec.
The BL_FO timer should be programmed before asserting BL_EN.

30.0

27.5

25.0

22.5

20.0

17.5

15.0

12.5

10.0

7.5

BACKLIGHT CURRENT (mA)

5.0

2.5

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-OUT TIME (Sec)

Figure 23. Linear Fade-Out Times

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-023

The time programmed in BL_FO represents the time it takes
the backlight current to go from 30 mA to 0 mA. Fading
between intermediate settings is shorter.

BACKLIGHT

CURRENT

FADE-IN

OFF-TO-MAX

MAX

DIM

BL_EN = 1 BL_EN = 0 BL_EN = 0 BL_EN = 0

MAX-TO-DIM

DIM_EN = 1

FADE-OUT

FADE-OUT

DIM-TO-OFF

FADE-OUT FADE-IN

FADE-OUTFADE-IN

BL_EN = 1 BL_EN = 1

Figure 24. Backlight Turn-On/Turn-Off/Dim with Fade Timers

Figure 24 shows the fade timers in use. With BL_FI and BL_FO
programmed, if BL_EN is asserted, the backlight fades in to its
maximum setting. If DIM_EN is asserted, the backlight fades
out to its dim setting. If BL_EN is cleared, the backlight fades
out to off.

During any point in a fade-out, if BL_EN is asserted, the
backlight stops at its current fade-out position and begins
fading in.

The fade-in and fade-out timers can be used independently of
each other; that is, fade-in can be enabled while fade-out is dis­abled. The fade timers can also be used with the off and dim timers.

Figure 25 shows the fade timers used with the dim and off timers.

BACKLIGHT

CURRENT

MAX

DIM

BL_EN = 1 BL_EN = 0

SET BY USER
SET BY INTERNAL STATE MACHINE

DIM TIMER

RUNNING

FADE -IN

FADE-OUT

DIM_EN = 1

OFF TIMER

RUNNING

DIM_EN = 0

Figure 25. Fade/Dim/Off Timers Used Together

FADE-OUT

07780-024

07780-025

Rev. 0 | Page 12 of 28

ADP5501

FADE OVERRIDE

A fade override feature allows the BL_FI and BL_FO timers to
be overridden when the BL_EN bit is reasserted (by the user
setting the FOVR bit in Register 0x02) during a fade-in or fade­out period and to set the backlight to its maximum setting.

BACKLIGHT

CURRENT

MAX

BL_EN = 1 BL_EN = 0 BL_EN = 0

FADE-IN

OVERRIDDEN

BL_EN = 1

(REASSERTED BY USER )

Figure 26. Fade Override

FADE-OUT

OVERRIDDEN

BL_EN = 1

(REASSERTED BY USER)

ADVANCED FADING (SQUARE)

Although the default linear fade algorithm gives a smooth
increase and decrease in backlight current, the resulting
increase and decrease in brightness still appear visually abrupt.
For example, for a given fade-in time, the eye notices an initial
increase in brightness as backlight current is increased but
cannot perceive much more increase in brightness as backlight
current is increased to maximum.

The reason for this is that the eye perceives changes in light
when the brightness of the light source is changed logarithmically
(Weber-Fechner law). To provide a more natural fading exper­ience to the user, the fade timers can be used in conjunction with
the square law approximation backlight codes (see Equation 2)
by setting BL_LAW = 01 in Register 0x02.

30.0

27.5

25.0

22.5

20.0

17.5

15.0

12.5

10.0

7.5

BACKLIGHT CURRENT (mA)

5.0

2.5

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-IN TI ME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

Figure 27. Square Law Fade-In Times

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-027

30.0

27.5

25.0

22.5

20.0

17.5

15.0

12.5

10.0

7.5

BACKLIGHT CURRENT (mA)

5.0

2.5

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-OUT TIME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-028

Figure 28. Square Law Fade-Out Times

ADVANCED FADING (CUBIC 1 AND CUBIC 2)

Two additional advanced settings in Register 0x02 are available

7780-026

for fading the backlight brightness levels, Cubic 1 (BL_LAW = 10)
and Cubic 2 (BL_LAW = 11). As shown in the backlight bright­ness control block diagram in Figure 14, linear fading and
square fading are implemented by ramping the 128 linear/square
algorithm codes at a fixed frequency over the duration of a
given fade-in/fade-out time.

Cubic fading is implemented by re-using the square algorithm
codes but ramping them with a clock source whose frequency
output increases as the sink current code increases (see Figure 29).
Cubic 1 and Cubic 2 have different frequency vs. code charac­teristics.

DAYLIGHT_MAX

DAYLIGHT_DIM

OFFICE_MAX

OFFICE_DIM

DARK_MAX

DARK_DIM

BL_LVL

BST

BL_VALUE

MUX

COUNTERS

BL_OFFT

BL_DIMT

BL_FI

BL_FO

AND

CONTROL

LOGIC

Figure 29. Backlight Brightness Control (Cubic)

BL_SNK

BL_EN

DIM_EN

BL_LAW

CLOCK

GENERATOR

07780-029

Rev. 0 | Page 13 of

28

ADP5501

Figure 30 shows a comparison of fading techniques. Cubic fades
complete faster than linear or square fades for a given fade time
setting. Cubic 1 completes approximately 30% faster, and Cubic 2
completes approximately 10% faster, than an equivalent linear
or square fade time.

With four fade laws and 15 fade time settings, the user can
easily find the right fade experience for an application.

30

25

20

CUBIC 1

L3_CMPR is used to detect when the photosensor output drops
below the programmable L3_TRIP point. If this event occurs,
the L3_OUT status signal is set. L3_CMPR contains program­mable hysteresis, meaning that the photosensor output must
rise above L3_TRIP + L3_HYS before L3_OUT is cleared.
L3_CMPR is enabled in Register 0x0C via the L3_EN bit. The
L3_TRIP and L3_HYS values of L3_CMPR can be set between
0 μA and 127 μA in steps of 0.5 μA (typical).

L2_TRIP

L2_HYS

15

10

BACKLIGHT CURRENT (mA)

5

0

0 0.2 0.4 0.6 0.8 1.0

Figure 30. Fade Law Comparison over a Unit Fade Time

LINEAR

UNIT FADE TIME

CUBIC 2

SQUARE

07780-030

AMBIENT LIGHT SENSING

The ADP5501 can be used in conjunction with an external
photosensor to detect when ambient light conditions drop
below programmable set points. An ADC samples the output of
the external photosensor. The ADC result is fed into two pro­grammable trip comparators. The ADC has an input range of
0 μA to 1000 μA (typical).

L2_EN

L2_TRIP

L2_HYS

FILTER

PHOTO
SENSOR
OUTPUT

ADC

Figure 31. Ambient Light Sensing and Trip Comparators

SETTINGS

L3_TRIP

L3_HYS

_

2

L

_

3

L

L3_EN

R

P

M

C

R

P

M

C

The Level 2 (office) light sensor comparator, L2_CMPR, is used
to detect when the photosensor output drops below the pro­grammable L2_TRIP point. If this event occurs, the L2_OUT
status signal is set. L2_CMPR contains programmable hysteresis,
meaning that the photosensor output must rise above L2_TRIP
+ L2_HYS before L2_OUT is cleared. L2_CMPR is enabled in
Register 0x0C via the L2_EN bit. The L2_TRIP and L2_HYS
values of L2_CMPR can be set between 0 μA and 1000 μA in steps
of 4 μA (typical).

L2_OUT

L3_OUT

L3_TRIP

L3_HYS

1 10 100 1000

ADC RANGE (µA)

Figure 32. Comparator Ranges

07780-032

The L2_CMPR and L3_CMPR comparators can be enabled
independently of each other. The ADC and comparators run
continuously when L2_EN and/or L3_EN is set during auto­matic backlight adjustment mode. A single conversion takes
80 ms (typical). Filter times of between 80 ms and 10 sec can be
programmed for the comparators before they change state.

It is also possible to use the light sensor comparators in a single­shot mode. After the single-shot measurement is completed, the
internal state machine clears the FORCE_RD bit in Register 0x0C.

The interrupt flag CMPR_INT is set in Register 0x00 if either of
the L2_OUT or L3_OUT status bits changes state, meaning that
interrupts can be generated if ambient light conditions transition
between any of the programmed trip points. CMPR_INT can
cause the

INT

pin to be asserted if the CMPR_IEN bit is set in
Register 0x01. The CMPR_INT flag can be cleared only by
writing a 1 to it.

AUTOMATIC BACKLIGHT ADJUSTMENT

The ambient light sensor comparators can be used to automat­ically transition the backlight among its three operating levels. To
enable this mode, the BL_AUTO_ADJ bit is set in Register 0x02.

07780-031

Once enabled, the internal state machine takes control of the
BL_LVL bits in Register 0x02 and changes them based on the
L2_OUT and L3_OUT status bits in Register 0x0C. The L2_OUT
status bit indicates that ambient light conditions have dropped
below the L2_TRIP point and the backlight should be moved to
its office (L2) level. The L3_OUT status bit indicates that ambient
light conditions have dropped below the L3_TRIP point and the
backlight should be moved to its dark (L3) level. Table 5 shows
the relationship between backlight operation and the ambient
light sensor comparator outputs.

Rev. 0 | Page 14 of 28

ADP5501

V

V

V

Table 5. Comparator Output Truth Table

BL_AUTO_ADJ L3_OUT L2_OUT Backlight Operation

0 X1 X

1

BL_LVL can be manually
set by the user.

1 0 0

BL_LVL = 00; backlight
operates at L1 (daylight).

1 0 1

BL_LVL = 01; backlight
operates at L2 (office).

1 1 0

BL_LVL = 10; backlight
operates at L3 (dark).

1 1 1

BL_LVL = 10; backlight
operates at L3 (dark).

1

X = don’t care.

The L3_OUT status bit has greater priority; therefore, the back­light operates at L3 (dark) even if L2_OUT is set.

LED CURRENT SINKS

The ADP5501 has three additional current sinks that can be
used as RGBs or auxiliary LED current sinks. Each current sink
is programmable up to 14 mA (typical) and can be independ­ently turned on and off.

The LED0 pin is the current sink for LED0. Its sink current can
be set using LED0_CURRENT in Register 0x14. LED0 sink can
be enabled with LED0_EN in Register 0x11.

The LED1 pin is the current sink for LED1. Its sink current can
be set using LED1_CURRENT in Register 0x15. LED1 sink can
be enabled with LED1_EN in Register 0x11.

The LED2 pin is the current sink for LED2. Its sink current can
be set using LED2_CURRENT in Register 0x16. LED2 sink can
be enabled with LED2_EN in Register 0x11.

These LEDx_CURRENT registers are six bits wide, allowing the
user to set the LED sink current to one of 64 different levels
between 0 mA and 14 mA. The ADP5501 can implement two
distinct algorithms to achieve a linear and a nonlinear relation­ship between input code and sink current.

BAT

By default, the ADP5501 uses a linear algorithm (LED_LAW = 0
in Register 0x11), where the LED sink current increases linearly
for a corresponding increase of input code. The LED sink current,
in milliamperes (mA), is determined by the following equation:

LED Sink Current = Code × (Fullscale_Current/63) (3)

where:

Code is the input code programmed by the user.
Fullscale_Current is the maximum sink current allowed

(typically, 14 mA).

The ADP5501 can also implement a nonlinear (square approx­imation) relationship between input code and LED sink current
level. In this case (LED_LAW = 1 in Register 0x11), the LED
sink current, in milliamperes (mA), is determined by the
following equation:

2

LED Sink Current =

⎛
⎜

Code

⎜
⎝

_

×

CurrentFullscale

63

⎞
⎟

(4)

⎟
⎠

Figure 33 shows the backlight current level vs. the input code
for both the linear and square law algorithms.

14

12

10

8

6

4

LED SINK CURRENT ( mA)

2

0

016324864

BAT

LINEAR

SQUARE

CODE

Figure 33. LED Sink Current vs. Code

BAT

07780-034

LED0_EN

LED0_CURRENT

LED0_OFFT

LED_ONT

LED_FI

LED_FO

LED_LAW

LED0

LED 1

DIGITAL

COUNTERS

AND

CONTROL

LED1_EN

LED1_CURRENT

LED1_OFFT

LED1

LED 2

DIGITAL

COUNTERS

AND

CONTROL

LED2_EN

LED2_CURRENT

LED2_OFF T

LED2

LED 3

DIGITAL

COUNTERS

AND

CONTRO L

07780-033

Figure 34. Status LED Current Sink

Rev. 0 | Page 15 of 28

ADP5501

Similar to the backlight current sink, the ADP5501 contains
timers to facilitate the smooth fading between off and on states
of the LED current sinks. All three LED sinks share a common
fade-in (LED_FI) timer as well as a common fade-out (LED_FO)
timer. The fade-in and fade-out timers are located in Register 0x13
and can be programmed to one of 15 settings ranging from 0.3 sec
to 5.5 sec. Fade-in times represent the time it takes to fade from
0 mA to 14 mA. Fade-out times represent the time it takes to fade
from 14 mA to 0 mA. Fading between intermediate settings is
shorter. The fade timers should be programmed before asserting
LEDx_EN in Register 0x11.

By default (LED_LAW = 0 in Register 0x11), the ADP5501
implements a fading scheme using the linear algorithm (see
Equation 3).

15

12

0.3 SEC

0.6 SEC

9

6

LED SINK CURRENT (mA)

3

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-IN TI ME (Sec)

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-035

Figure 35. Linear Fade-In Times

15

12

9

6

LED SINK CURRENT (mA)

3

0

0 0.51.01.52.02.53.03.54.04.55.05.5

FADE-OUT T IME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-036

Figure 36. Linear Fade-Out Times

To provide a more natural fading experience for the user, the
fade timers can be used in conjunction with the square law
approximation codes (see Equation 4) by setting LED_LAW = 1.

15

12

9

6

LED SINK CURRENT (mA)

3

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-IN TI ME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-037

Figure 37. Square Law Fade-In Times

15

12

9

6

LED SINK CURRENT (mA)

3

0

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

FADE-OUT T IME (Sec)

0.3 SEC

0.6 SEC

0.9 SEC

1.2 SEC

1.5 SEC

1.8 SEC

2.1 SEC

2.4 SEC

2.7 SEC

3.0 SEC

3.5 SEC

4.0 SEC

4.5 SEC

5.0 SEC

5.5 SEC

07780-038

Figure 38. Square Law Fade-Out Times

The LED current sinks have additional timers to facilitate blinking
functions. A shared on timer (LED_ONT in Register 0x12) used
in conjunction with three off timers (LED0_OFFT, LED1_OFFT,
and LED2_OFFT) allows the LED current sinks to be configured
in various blinking modes. The on timer can be set to four
different settings: 0.2 sec, 0.6 sec, 0.8 sec, and 1.2 sec. The off
timers also have four different settings: disabled, 0.6 sec, 0.8 sec,
and 1.2 sec. Blink mode is activated by setting the off timers to
any setting other than disabled.

All fade-on and fade-off timers should be programmed before
enabling any of the LED current sinks. If LEDx is on during a
blink cycle and LEDx_EN is cleared, LEDx goes off (or fades to
off if fade-out is enabled). If LEDx is off during a blink cycle and
LEDx_EN is cleared, LEDx stays off.

Rev. 0 | Page 16 of

28

ADP5501

V

LEDx

CURRENT

ON TIME ON TIME

FADE-IN FADE-OUT FADE-IN FADE-O UT

MAX

LEDx_EN = 1

OFF

TIME

Figure 39. LEDx Blink Mode with Fading

OFF

TIME

INTERRUPT OUTPUT (INT)

The ADP5501 can generate interrupts to an external processor via

INT

its interrupt output,
should be pulled up to VDDIO.
several internal blocks, as shown in . Figure 40

INT

.

is an active low, open-drain pin that

INT

can be asserted by one of

DDIO

ALS COMPARATO R INTERRUPTS

INT

07780-040

OVERVOLTAGE INTERRUPT

Figure 40.

INT

Pin Drive

OR

RESET INPUT (RST)

The ADP5501 can be restored to a power-on reset state if the
RST

pin is held low.

the pin must be held low for greater than 75 μs (typical) before a

07780-039

reset occurs.

RST

contains a debounce circuit; therefore,

Rev. 0 | Page 17 of 28

ADP5501

COMMUNICATON INTERFACE

Communication with the ADP5501 is done via its I2C­compatible serial interface. Figure 41 shows a typical write
sequence for programming an internal register.

1.

The cycle begins with a start condition, followed by the

chip write address (0x64).

2.

The ADP5501 acknowledges the chip write address byte by

pulling the data line low.

3.

The address of the register to which data is to be written is

sent next.

4.

The ADP5501 acknowledges the register address byte by

pulling the data line low.

5.

The data byte to be written to is sent next.

6.

The ADP5501 acknowledges the data byte by pulling the

data line low.

7.

A stop condition completes the sequence.

0 = WRITE

ST SP

10101000 000

Figure 42 shows a typical read sequence for reading back an
internal register.

The cycle begins with a start condition, followed by the

1.

chip write address (0x64).

2.

The ADP5501 acknowledges the chip write address byte by

pulling the data line low.

3.

The address of the register from which data is to be read is

sent next.

4.

The ADP5501 acknowledges the register address byte by

pulling the data line low.

5.

The cycle continues with a repeat start, followed by the

chip read address (0x65).

6.

The ADP5501 acknowledges the chip read address byte by

pulling the data line low.

7.

The ADP5501 places the contents of the previously

addressed register on the bus for readback.

8.

There is a no acknowledge following the readback data

byte, and the cycle is completed with a stop condition.

CHIP ADDRESS

REGISTE R ADDRESS ADP5501 RECEIVES DAT A

DP5501 ACK

Figure 41. I

2

C Write Sequence

DP5501 ACK

DP5501 ACK

07780-041

0 = WRITE

ST ST

10101000 1 010100000

CHIP ADDRESS REGIST ER ADDRESS CHIP ADDRESS ADP5501 SENDS DATA

DP5501 ACK

Figure 42. I

DP5501 ACK

2

C Read Sequence

1 = READ

DP5501 ACK

SP

1

NO ACK

07780-042

Rev. 0 | Page 18 of 28

ADP5501

REGISTER MAP

All registers are 0 on reset. Unused bits are read as 0.

Table 6.

Register
Address

0x00 MODE_STATUS Sets the device operating mode; contains enables for backlight on/dim and top level interrupt status bits.
0x01 INTERRUPT_ENABLE

0x02 BL_CONTROL Sets parameters relating to backlight control.
0x03 BL_TIME Contains backlight off and dim timers.
0x04 BL_FADE Contains backlight fade-in and fade-out timers.
0x05 DAYLIGHT_MAX Sets the daylight (L1) maximum current.
0x06 DAYLIGHT_DIM Sets the daylight (L1) dim current.
0x07 OFFICE_MAX Sets the office (L2) maximum current.
0x08 OFFICE_DIM Sets the office (L2) dim current.
0x09 DARK_MAX Sets the dark (L3) maximum current.
0x0A DARK_DIM Sets the dark (L3) dim current.
0x0B BL_VALUE Read-only register of what the backlight is presently set to.
0x0C ALS_CMPR_CFG Sets enables and filters for ambient light sensor comparators; contains comparator output status bits.
0x0D L2_TRIP Sets the light sensor comparator (L2_CMPR) threshold point.
0x0E L2_HYS Sets the light sensor comparator (L2_CMPR) hysteresis.
0x0F L3_TRIP Sets the light sensor comparator (L3_CMPR) threshold point.
0x10 L3_HYS Sets the light sensor comparator (L3_CMPR) hysteresis.
0x11 LED_SINK_CONTROL Contains enables and configuration for the LED current sinks.
0x12 LED_TIME Contains the on and off timers for the status LED current sinks.
0x13 LED_FADE Contains the fade-in and fade-out timers for the status LED current sinks.
0x14 LED0_CURRENT Sets the LED0 sink current.
0x15 LED1_CURRENT Sets the LED1 sink current.
0x16 LED2_CURRENT Sets the LED2 sink current.

Register Name Register Description

Contains enables for allowing interrupts to assert INT

.

Rev. 0 | Page 19 of 28

ADP5501

DETAILED REGISTER DESCRIPTIONS

Table 7. Register 0x00, Device Mode and Status (MODE_STATUS)

Bit Name R/W Description

7

STNBY

6 BL_EN R/W 0 = the backlight driver is disabled.

5 DIM_EN R/W 0 = dim mode is disabled.

1

4

1

3

OVP_INT R/W 0 = no overvoltage protection (OVP) condition.

CMPR_INT R/W 0 = no ambient light sensor comparators have triggered.

2 to 0 Not used

1

If one of the interrupt bits is cleared and there is a pending interrupt,

R/W 0 = the device is in standby mode. (If 1.8V ≤ VDDIO ≤ 2.7V, then I2C.)

1 = the device is in operating mode. Additional functions such as backlight driver, LED sinks, and
ambient light sensor functions can be enabled.

1 = the backlight driver is enabled.

1 = dim mode is enabled.
Dim mode can be enabled in two ways. One is by manually setting this bit, in which case, the

backlight stays at a dim level until this bit is manually cleared. The second method is by setting the
DIMT timer, in which case, an internal state machine sets this bit and clears it when the timer expires.

1 = OVP condition detected.
Once set, this bit can be cleared by writing a 1 to it.

1 = one of the ambient light sensor comparators has triggered.
Once set, this bit can be cleared by writing a 1 to it.

INT

deasserts for 50 s and reasserts, but the status of the pending interrupt stays set.

Table 8. Register 0x01, Interrupt Enable (INTERRUPT_ENABLE)

Bit Name R/W Description

7 to 5 Not used
4 AUTO_LD_EN R/W 0 = autoload is disabled.

1 = autoload is enabled. A 1 mA dummy load turns on when the backlight code is less than 8 (linear
law) or less than Code 32 (square law).

3 CMPR_IEN R/W 0 = ambient light sensor comparator(s) interrupt is disabled.

1 = ambient light sensor comparator(s) interrupt is enabled.

2 OVP_IEN R/W 0 = OVP interrupt is disabled.

1 = OVP interrupt is enabled.

1 to 0 Not used

Table 9. Register 0x02, Backlight Control (BL_CONTROL)

Bit Name R/W Description

7 to 6 BL_LVL R/W Brightness level control for the backlight.

00 = daylight (L1).
01 = office (L2).
10 = dark (L3).
See the description for the BL_AUTO_ADJ bit.

5 to 4 BL_LAW R/W Backlight fade-on/fade-off transfer characteristic.

00 = linear.
01 = square.
10 = Cubic 1.
11 = Cubic 2.

Rev. 0 | Page 20 of 28

ADP5501

Bit Name R/W Description

3

2 OVP_EN R/W 0 = soft OVP protection disabled.

1 FOVR R/W 0 = backlight fade override is disabled.

0 Not used

BL_AUTO_AD
J

Table 10. Register 0x03, Backlight Off and Dim Timers (BL_TIME)

Bit Name R/W Description

7 to 4 BL_OFFT R/W Backlight off timer; the timer should be set before BL_EN is set.

3 to 0 BL_DIMT R/W Backlight dim timer; the timer should be set before BL_EN is set.

R/W

0 = ambient light sensor comparators have no effect on the backlight operating level. The user can
manually adjust the backlight operating level using the BL_LVL bits.

1 = ambient light sensor comparators automatically adjust the backlight operating level. The internal
state machine takes control of the BL_LVL bits.

1 = soft OVP protection enabled.

1 = backlight fade override is enabled.

0000 = the timer is disabled.
0001 = 10 sec.
0010 = 15 sec.
0011 = 20 sec.
0100 = 25 sec.
0101 = 30 sec.
0110 = 35 sec.
0111 = 40 sec.
1000 = 50 sec.
1001 = 60 sec.
1010 = 70 sec.
1011 = 80 sec.
1100 = 90 sec.
1101 = 100 sec.
1110 = 110 sec.
1111 = 120 sec.

0000 = the timer is disabled.
0001 = 10 sec.
0010 = 15 sec.
0011 = 20 sec.
0100 = 25 sec.
0101 = 30 sec.
0110 = 35 sec.
0111 = 40 sec.
1000 = 50 sec.
1001 = 60 sec.
1010 = 70 sec.
1011 = 80 sec.
1100 = 90 sec.
1101 = 100 sec.
1110 = 110 sec.
1111 = 120 sec.

Rev. 0 | Page 21 of 28

ADP5501

Table 11. Register 0x04, Backlight Fade-In and Fade-Out Timers (BL_FADE)

Bit Name R/W Description

7 to 4 BL_FO R/W Backlight fade-out timer; the timer should be set before BL_EN is set.

0000 = the timer is disabled.
0001 = 0.3 sec.
0010 = 0.6 sec.
0011 = 0.9 sec.
0100 = 1.2 sec.
0101 = 1.5 sec.
0110 = 1.8 sec.
0111 = 2.1 sec.
1000 = 2.4 sec.
1001 = 2.7 sec.
1010 = 3.0 sec.
1011 = 3.5 sec.
1100 = 4.0 sec.
1101 = 4.5 sec.
1110 = 5.0 sec.
1111 = 5.5 sec.

3 to 0 BL_FI R/W Backlight fade-in timer; the timer should be set before BL_EN is set.

0000 = the timer is disabled.
0001 = 0.3 sec.
0010 = 0.6 sec.
0011 = 0.9 sec.
0100 = 1.2 sec.
0101 = 1.5 sec.
0110 = 1.8 sec.
0111 = 2.1 sec.
1000 = 2.4 sec.
1001 = 2.7 sec.
1010 = 3.0 sec.
1011 = 3.5 sec.
1100 = 4.0 sec.
1101 = 4.5 sec.
1110 = 5.0 sec.
1111 = 5.5 sec.

Table 12. Register 0x05, Level 1 (Daylight) Maximum Current (DAYLIGHT_MAX)

Bit Name R/W Description

7 Not used
6 to 0 DAYLIGHT_MAX R/W Maximum current setting for the backlight when BL_LVL is at Level 1 (daylight).

See Figure 16 for the backlight current vs. sink code relationship.

Table 13. Register 0x06, Level 1 (Daylight) Dim Current (DAYLIGHT_DIM)

Bit R/W Description

7 Not used
6 to 0 DAYLIGHT_DIM R/W Dim current setting for the backlight when BL_LVL is at Level 1 (daylight).

See Figure 16 for the backlight current vs. sink code relationship.

Table 14. Register 0x07, Level 2 (Office) Maximum Current (OFFICE_MAX)

Bit Name R/W Description

7 Not used
6 to 0 OFFICE_MAX R/W Maximum current setting for the backlight when BL_LVL is at Level 2 (office).

See Figure 16 for the backlight current vs. sink code relationship.

Rev. 0 | Page 22 of 28

ADP5501

Table 15. Register 0x08, Level 2 (Office) Dim Current (OFFICE_DIM)

Bit Name R/W Description

7 Not used
6 to 0 OFFICE_DIM R/W Dim current setting for the backlight when BL_LVL is at Level 2 (office).

See Figure 16 for the backlight current vs. sink code relationship.

Table 16. Register 0x09, Level 3 (Dark) Maximum Current (DARK_MAX)

Bit Name R/W Description

7 Not used
6 to 0 DARK_MAX R/W Maximum current setting for the backlight when BL_LVL is at Level 3 (dark).

See Figure 16 for the backlight current vs. sink code relationship.

Table 17. Register 0x0A, Level 3 (Dark) Dim Current (DARK_DIM)

Bit Name R/W Description

7 Not used
6 to 0 DARK_DIM R/W Dim current setting for the backlight when BL_LVL is at Level 3 (dark).

See Figure 16 for the backlight current vs. sink code relationship.

Table 18. Register 0x0B, Backlight Current Value (BL_VALUE)

Bit Name R/W Description

7 Not used
6 to 0 BL_VALUE R Read-only register that contains the present value to which the backlight is programmed.

Table 19. Register 0x0C, Light Sensor Comparator Configuration (ALS_CMPR_CFG)

Bit Name R/W Description

7 to 5 FILT R/W Light sensor filter time.

000 = 0.08 sec.
001 = 0.16 sec.
010 = 0.32 sec.
011 = 0.64 sec.
100 = 1.28 sec.
101 = 2.56 sec.
110 = 5.12 sec.
111 = 10.24 sec.

4 FORCE_RD R/W Forces the light sensor comparator to perform a single conversion.

This bit is cleared by the internal state machine once the conversion is complete.

3 L3_OUT R 0 = ambient light is greater than Level 3 (dark).

1 = the light sensor comparator has detected a change in ambient light from Level 2 (office) to Level
3 (dark).

2 L2_OUT R 0 = ambient light is greater than Level 2 (office).

1 = the light sensor comparator has detected a change in ambient light from Level 1 (daylight) to
Level 2 (office).

1 L3_EN R/W 0 = disable Comparator L3_CMPR .

1 = enable Comparator L3_CMPR. If automatic backlight adjustment is required, BL_AUTO_ADJ
must be set also.

0 L2_EN R/W 0 = disable Comparator L2_CMPR.

1 = enable Comparator L2_CMPR. If automatic backlight adjustment is required, BL_AUTO_ADJ
must be set also.

Table 20. Register 0x0D, Level 2 (Office) Comparator Trip Point (L2_TRIP)

Bit Name R/W Description

6 to 0 L2_TRIP R/W

Sets the trip value for Comparator L2_CMPR. If ambient light levels fall below this trip point, L2_OUT
is set. Each code is equal to 4 µA (typical). Full scale is 1000 µA (typical).

Rev. 0 | Page 23 of 28

ADP5501

Table 21. Register 0x0E, Level 2 (Office) Comparator Hysteresis (L2_HYS)

Bit Name R/W Description

6 to 0 L2_HYS R/W

Table 22. Register 0x0F, Level 3 (Dark) Comparator Trip Point (L3_TRIP)

Bit Name R/W Description

6 to 0 L3_TRIP R/W

Table 23. Register 0x10, Level 3 (Dark) Comparator Hysteresis (L3_HYS)

Bit Name R/W Description

6 to 0 L3_HYS R/W

Table 24. Register 0x11, LED Control (LED_SINK_CONTROL)

Bit Name R/W Description

7 to 4 Not used
3 LED_LAW R/W LED current sink fade-on/fade-off transfer characteristic.

2 LED2_EN R/W 0 = LED2 sink is disabled.

1 LED1_EN R/W 0 = LED1 sink is disabled.

0 LED0_EN R/W 0 = LED0 sink is disabled.

Sets the hysteresis value for Comparator L2_CMPR. If ambient light levels increase above L2_TRIP + L2_HYS,
L2_OUT is cleared. Each code is equal to 4 µA (typical). Full scale is 1000 µA (typical).

Sets the trip value for Comparator L3_CMPR. If ambient light levels fall below this trip point, L3_OUT is
set. Each code is equal to 0.5 µA (typical). Full scale is 127 µA (typical).

Sets the hysteresis value for Comparator L3_CMPR. If ambient light levels increase above L3_TRIP + L3_HYS,
L3_OUT is cleared. Each code is equal to 0.5 µA (typical). Full scale is 127 µA (typical).

0 = linear.
1 = square.

1 = LED2 sink is enabled.

1 = LED1 sink is enabled.

1 = LED0 sink is enabled.

Table 25. Register 0x12, LED On and Off Timers (LED_TIME)

Bit Name R/W Description

7 to 6 LED_ONT R/W

5 to 4 LED2_OFFT R/W

3 to 2 LED1_OFFT R/W

1 to 0 LED0_OFFT R/W

Sets the LED on time when used in conjunction with the LEDx_OFFT timer to perform LED blinking. All
three LED sinks share this common timer.

00 = 0.2 sec.
01 = 0.6 sec.
10 = 0.8 sec.
11 = 1.2 sec.

Sets the LED2 off time when used in conjunction with the LED_ONT timer to perform LED blinking. LED2
stays on continuously if the timer is disabled.

00 = LED2 timer is disabled.
01 = 0.6 sec.
10 = 0.8 sec.
11 = 1.2 sec.

Sets the LED1 off time when used in conjunction with the LED_ONT timer to perform LED blinking. LED1
stays on continuously if the timer is disabled.

00 = LED1 timer is disabled.
01 = 0.6 sec.
10 = 0.8 sec.
11 = 1.2 sec.

Sets the LED0 off time when used in conjunction with the LED _ONT timer to perform LED blinking.
LED0 stays on continuously if the timer is disabled.
00 = LED0 timer is disabled.
01 = 0.6 sec.

10 = 0.8 sec.
11 = 1.2 sec.

Rev. 0 | Page 24 of 28

ADP5501

Table 26. Register 0x13, LED Fade-In and Fade-Out Timers (LED_FADE)

Bit Name R/W Description

7 to 4 LED_FO R/W LED fade-out timer; the timer should be set before LEDx_EN is enabled.

0000 = the timer is disabled.
0001 = 0.3 sec.
0010 = 0.6 sec.
0011 = 0.9 sec.
0100 = 1.2 sec.
0101 = 1.5 sec.
0110 = 1.8 sec.
0111 = 2.1 sec.
1000 = 2.4 sec.
1001 = 2.7 sec.
1010 = 3.0 sec.
1011 = 3.5 sec.
1100 = 4.0 sec.
1101 = 4.5 sec.
1110 = 5.0 sec.
1111 = 5.5 sec.

3 to 0 LED _FI R/W LED fade-in timer; the timer should be set before LEDx_EN is enabled.

0000 = the timer is disabled.
0001 = 0.3 sec.
0010 = 0.6 sec.
0011 = 0.9 sec.
0100 = 1.2 sec.
0101 = 1.5 sec.
0110 = 1.8 sec.
0111 = 2.1 sec.
1000 = 2.4 sec.
1001 = 2.7 sec.
1010 = 3.0 sec.
1011 = 3.5 sec.
1100 = 4.0 sec.
1101 = 4.5 sec.
1110 = 5.0 sec.
1111 = 5.5 sec.

Table 27. Register 0x14, LED0 Sink Current (LED0_CURRENT)

Bit Name R/W Description

7 to 6 Not used
5 to 0 LED0_CURRENT R/W Sink current setting for LED0.

See Figure 33 for LED sink current vs. code relationship.

Table 28. Register 0x15, LED1 Sink Current (LED1_CURRENT)

Bit Name R/W Description

7 to 6 Not used
5 to 0 LED1_CURRENT R/W Sink current setting for LED1.

See Figure 33 for LED sink current vs. code relationship.

Table 29. Register 0x16, LED2 Sink Current (LED2_CURRENT)

Bit Name R/W Description

7 to 6 Not used
5 to 0 LED2_CURRENT R/W Sink current setting for LED2.

See Figure 33 for the LED sink current vs. code relationship.

Rev. 0 | Page 25 of 28

ADP5501

VINV

APPLICATIONS INFORMATION

CONVERTER TOPOLOGY

The ADP5501 backlight driver uses a dc-to-dc step-up (boost)
converter to achieve the high voltage levels required to drive up
to six white LEDs in series. Figure 43 shows the basic asynchronous
boost converter topology.

OUT

07780-043

Figure 43. Basic Asynchronous Boost Converter Topology

Assuming an initial steady state condition where the switch has
been open for a long time, the output voltage (VOUT) is equal to
the input voltage (VIN), minus a diode drop.

If the switch is closed, the output voltage maintains its value as
the diode blocks its path to ground. The inductor, however, has
a voltage differential across its terminals. Current in an inductor
cannot change instantaneously, so it increases linearly at a rate of

di/dt = VIN/L

where L is the inductance value in henrys.

If the switch is kept closed, the current increases until the inductor
reaches its saturation limit, at which point the inductor becomes
a dc path to ground. Therefore, the switch should be kept closed
only long enough to build some transient energy in the inductor
but not so long that the inductor becomes saturated.

When the switch is opened, the current that has built up in the
inductor continues to flow (because the current in an inductor
cannot change instantaneously), so the voltage at the top of the
switch increases and forward biases the diode, allowing the
inductor current to charge the capacitor and, therefore, increase
the overall output voltage level. If the switch is opened and
closed continuously, the output voltage continues to increase.

Figure 44 shows the boost configuration used in the ADP5501.
A Schottky diode is used due to its fast turn-on time and low
forward voltage drop. An input capacitor is added to reduce ripple
voltage that is generated on the input supply due to charging/
discharging of the inductor. An integrated power switch is used
to control current levels in the inductor. A control loop consisting
of a feedback signal, some safety limiting features, and a switch
drive signal complete the boost converter topology.

27V

I-LIMIT

BOOST

CONTROL

1µF

22

OVP

THERMAL S/D

BST

AUTO
LOAD

BL_SNK

FB

BACKLIGHT

CURRENT
CONTROL

23

0.65V

VBAT

1µF

PGND

VBAT

4.7µH

1

21

SW

2

Figure 44. Boost Configuration

The ADP5501 uses a current-limiting, pulse frequency modu­lation (PFM) control scheme. For medium to large output
currents, the converter operates in pseudo continuous conduc­tion mode (CCM). It generates bursts of peak current limited
pulses (600 mA typical) in the inductor, as shown in Figure 9.

For light output currents, the converter operates in pseudo
discontinuous conduction mode (DCM). It generates bursts of
small (200 mA, typical) and medium (400 mA, typical) current
pulses in the inductor, as shown in Figure 11.

To maintain reasonable burst frequencies during very light load
conditions, an automatic dummy load feature is available. When
enabled, the 1 mA dummy load is activated if the backlight sink
current code drops below 8 while in linear law mode or if the
backlight sink current code drops below 32 while in square law
mode.

Safety Features

The ADP5501 uses an overvoltage protection (OVP) circuit that
monitors the boosted voltage on the output capacitor. If the
LED string becomes open (due to a broken LED), the control
circuit continually commands the boost voltage to increase.
If the boost level exceeds the maximum process rating for the
ADP5501, damage to the device can occur. The ADP5501 boost
converter has an OVP limit of 27 V (typical).

The ADP5501 also has a feature that ramps down the backlight
code when an OVP condition is detected. This may be useful in
conditions where LEDs with marginally high forward voltages
are used in low ambient conditions. The feature can be enabled
by setting the OVP_EN bit in Register 0x02.

The ADP5501 also features a thermal shutdown circuit. When
the die junction temperature reaches 150°C (typical), the boost
converter shuts down. It remains shut down until the die
temperature falls by 10°C (typical).

07780-044

Rev. 0 | Page 26 of 28

ADP5501

G

Component Selection

The ADP5501 boost converter is designed for use with a 4.7 μH
inductor. Choose an inductor with a sufficient current rating to
prevent it from going into saturation. The peak current limit of
the ADP5501 is 750 mA (maximum), so choose an inductor
with a greater saturation rating. To maximize efficiency, choose
an inductor with a low series resistance (DCR).

The ADP5501 is an asynchronous boost and, as such, requires
an external Schottky diode to conduct the inductor current to
the output capacitor and LED string when the power switch is
off. Ensure that the Schottky diode peak current rating is greater
than the maximum inductor current. Choose a Schottky diode
with an average current rating that is significantly larger than
the maximum LED current. To prevent thermal runaway, derate
the Schottky diode to ensure reliable operation at high junction
temperatures. To maximize efficiency, select a Schottky diode
with a low forward voltage. When the power switch is on, the
Schottky diode blocks the dc path from the output capacitor to
ground. Therefore, choose a Schottky diode with a reverse
breakdown greater than the maximum boost voltage. A 40 V,
1 A Schottky diode is recommended.

The input capacitor carries the input ripple current, allowing
the input power source to supply only the dc current. Use an
input capacitor with sufficient ripple current rating to handle
the inductor ripple. A 1 μF X5R/X7R ceramic capacitor rated
for 16 V dc bias is recommended for the input capacitance.

The output capacitor maintains the output voltage when the
Schottky diode is not conducting. Due to the high levels of
boost voltage required, a 1 μF X5R/X7R ceramic capacitor rated
for 50 V dc bias is recommended for output capacitance.

Note that dc bias characterization data is available from
capacitor manufacturers and should be taken into account
when selecting input and output capacitors.

GND

PCB LAYOUT

Good PCB layout is important to maximize efficiency and to
minimize noise and electromagnetic interference (EMI). To
minimize large current loops, place the input capacitor, inductor,
Schottky diode, and output capacitor as close as possible to each
other and to the ADP5501 using wide tracks (use shapes where
possible).

For thermal relief, the exposed pad of the LFCSP package
should be connected to ground (GND). PGND and GND
should be connected to each other at the bottom of the output
capacitor.

Figure 46 shows an example PCB layout with the main power
components required for backlight driving

EXAMPLE CIRCUIT

2.7V TO 5. 5V

3.3V

10kΩ

10kΩ

1µF

1

21

16

2.2kΩ

2.2kΩ

5

4

3

15

Figure 45. Typical Configuration Circuit

1µF

4.7µH

2

SW22BST

PGND

VBAT

VDDIO

SCL

SDA

INT

RST

6NC7NC8NC9NC10NC11NC12

ADP5501

LED1

BL_SNK

CAP_OUT

RGB

LED2

13

23

GND

GND

GND

CMP_IN

LED0

14

20

1µF

19

18

24

100nF

17

3.3V

3.3V

07780-046

VBAT

SOLUTION SIZE
APPROXIMATELY 47mm

GNDGND

BL_SNK

ADP

CONNE
EXPO

PAD TO

NCNCNC

BST

PGND

SW

INT

2

SDA

SCL

NC

5501

CT

SED

GND

VBAT

CMP_IN

CAP_OUT

NCNCLED1

GND

VDDIO

RST

LED0
LED2

TOP OF LED STRING

BOTTOM OF LED STRIN

07780-045

Figure 46. Example PCB Layout

Rev. 0 | Page 27 of 28

ADP5501

OUTLINE DIMENSIONS

INDICATOR

1.00

0.85

0.80

PIN 1

12° MAX

SEATING
PLANE

4.00

BSC SQ

TOP

VIEW

0.80 MAX

0.65 TYP

*

COMPLIANT TO JEDEC STANDARDS MO-220-VGG D- 2
EXCEPT FOR EXPOSED PAD DIMENSION

0.30

0.23

0.18

3.75

BSC SQ

0.20 REF

0.60 MAX

0.05 MAX

0.02 NOM
COPLANARITY

BSC

0.08

0.50

0.50

0.40

0.30

0.60 MAX

1

24

19

18

EXPOSED

PA D

(BOTTOMVIEW)

13

12

2.50 REF

6

7

FOR PROPER CONNE CT I O N O F
THE EXPOSED PAD, REFER TO
THE PIN CONF IGURATIO N AND
FUNCTION DES CRIPTIONS
SECTION O F THIS DATA SHEET.

Figure 47. 24-Lead Lead Frame Chip Scale Package [LFCSP_VQ]

4 mm × 4 mm Body, Very Thin Quad

(CP-24-2)

Dimensions shown in millilmeters

PIN 1
INDICATOR

*

2.45

2.30 SQ

2.15

0.23 MIN

080808-A

ORDERING GUIDE

Model Temperature Range Package Description Package Option

ADP5501ACPZ-RL

1

Z = RoHS Compliant Part.

1

−40°C to +85°C 24-Lead Lead Frame Chip Scale Package [LFCSP_VQ] CP-24-2

©2008 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07780-0-10/08(0)

Rev. 0 | Page 28 of 28