ANALOG DEVICES ADP8863 Service Manual

Charge Pump, 7-Channel

FEATURES

Automated blinking and funlight timing for each LED driver
16 programmable fade in and fade out times

0.1 sec to 5.5 sec
Selectable linear, square, or cubic fade rates

7 independent and programmable LED drivers

7 drivers capable of 30 mA (maximum)

1 driver also capable of 60 mA (maximum)
Programmable maximum current limit (128 levels)
Separate and independent controls for backlight LEDs
Backlight fade override
Up to two built-in comparator inputs with programmable

modes for ambient light sensing
Charge pump with automatic gain selection of 1×, 1.5×, and

2× for maximum efficiency
Standby mode for <1 μA current consumption

2

I

C-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
Operation down to V

(UVLO) at V

IN

Available in a small 20-ball, 2.15 mm × 2.36 mm × 0.6 mm

WLCSP or a 20-lead, 4 mm × 4 mm × 0.75 mm LFCSP

= 2.5 V with undervoltage lockout

IN

= 2.0 V

VIN

nRST

nINT

SDA

SCL

Fun Lighting LED Driver

TYPICAL OPERATING CIRCUIT

D1 D2 D3 D4 D5 D6 D7

C

IN

1µF

VDDIO

GND1 GND2

ADP8863

Figure 1.

ADP8863

V

ALS

PHOTO

CMP_IN

SENSOR

VOUT

C1+

C1–
C2+

C2–

0.1µF

C

OUT

1µF

C1
1µF

C2
1µF

08392-001

APPLICATIONS

LED indication
Funlight indicator lighting
Keypad backlighting
RGB LED color generation and mixing
General backlighting of small format displays

GENERAL DESCRIPTION

The ADP8863 combines a powerful charge pump driver with
advanced autonomous LED lighting features. It allows as
many as seven LEDs to be independently driven up to 30 mA
(maximum). The seventh LED can also be driven to 60 mA
(maximum). All LEDs are programmable for maximum current
and fade in/fade out times via the I

Additionally, automated blinking routines can be independently
programmed and enabled for all seven LED channels. These
LEDs can also be combined into groups to reduce the processor
instructions.

Rev. A

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 interface.

This entire configuration is driven by a two-capacitor charge pump
with gains of 1×, 1.5×, and 2×. The charge pump is capable of
driving a maximum I

of 240 mA from a supply of 2.5 V to

OUT

5.5 V. The device includes a variety of safety features including
short-circuit, overvoltage, and overtemperature protection.
These features allow 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.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2010 Analog Devices, Inc. All rights reserved.

ADP8863

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications ....................................................................................... 1

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

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

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

Specifications ..................................................................................... 3

I2C Timing Diagram .................................................................... 4

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

Maximum Temperature Ranges ................................................. 5

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

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

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

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

Theory of Operation ...................................................................... 11

Power Stage.................................................................................. 12

Operating Modes ........................................................................ 13

LED Groupings ........................................................................... 14

LED Current Settings ................................................................. 14

Automated Fade In and Fade Out ............................................ 14

Independent Sink Control ......................................................... 15

RGB Color Generation .............................................................. 15

Automated RGB Color Fades ................................................... 15

Backlight Operating Levels ....................................................... 16

Backlight Turn On/Turn Off/Dim ........................................... 16

Automatic Dim and Turn Off Timers ..................................... 16

Fade Override ............................................................................. 17

Ambient Light Sensing .............................................................. 17

Automatic Backlight Adjustment ............................................. 18

Using the ADP8863 to Drive Additional LEDs ...................... 19

Operating LEDs from Alternative Supplies ............................ 20

Short-Circuit Protection Mode ................................................ 21

Overvoltage Protection .............................................................. 21

Thermal Shutdown/Overtemperature Protection ................. 21

Interrupts ..................................................................................... 21

Applications Information .............................................................. 23

Layout Guidelines....................................................................... 23

I2C Programming and Digital Control ........................................ 24

Backlight Register Descriptions ............................................... 29

Independent Sink Register Descriptions ................................. 36

Comparator Register Descriptions .......................................... 44

Outline Dimensions ....................................................................... 48

Ordering Guide .......................................................................... 49

REVISION HISTORY

6/10—Rev. 0 to Rev. A

Changes to Features Section and General Description Section . 1

Changes to Thermal Resistance Section and Table 3 ................... 5

Added Figure 4; Renumbered Sequentially .................................. 6

Changes to Table 4 ............................................................................ 6

Updated Outline Dimensions ....................................................... 48

Changes to Ordering Guide .......................................................... 49

4/10—Revision 0: Initial Version

Rev. A | Page 2 of 52

ADP8863

SPECIFICATIONS

VIN = 3.6 V, SCL = 2.7 V, SDA = 2.7 V, nINT = open, nRST = 2.7 V, CMP_IN = 0 V, V

= 1 F, typical values are at TA = 25°C and are not guaranteed, minimum and maximum limits are guaranteed from TA = −40°C to

C

OUT

+85°C, unless otherwise noted.

Table 1.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

SUPPLY

Input Voltage

Operating Range VIN 2.5 5.5 V
Start-Up Level V
Low Level V

V

Hysteresis V

IN(START)

UVLO Noise Filter t

VIN increasing 2.05 2.30 V

IN(START)

VIN decreasing 1.75 1.97 V

IN(STOP)

After startup 80 mV

IN(HYS)

10 s

UVLO

Quiescent Current IQ

Prior to V
During Standby I
After Startup and Switching I

I

IN(START)

Q(START)

VIN = 3.6 V, Bit nSTBY = 0, SCL = SDA = 0 V 0.3 1.0 A

Q(STBY)

Q(ACTIVE)

VIN = V

= 3.6 V, Bit nSTBY = 1, I

V

IN

− 100 mV 10 A

IN(START)

OUT

gain = 2×

OSCILLATOR

Switching Frequency fSW 0.8 1 1.32 MHz
Duty Cycle D 50 %

OUTPUT CURRENT CONTROL

Maximum Drive Current I

D1:D7(MAX)

V

D1:D7

= 0.4 V

D1 to D7 Bit SCR = 0 in the ISC7 register

TJ = 25°C 26.2 30 34.1 mA
TJ = −40°C to +85°C 24.4 34.1 mA

D7 Only (60 mA Setting) I

VD7 = 0.4 V, Bit SCR = 1 in the ISC7 register

D7(60 mA)

TJ = 25°C 52.5 60 67 mA
TJ = −40°C to +85°C 48.8 67 mA

LED Current Source Matching1 I

All Current Sinks I

D2 to D7 Current Sinks I
Leakage Current on LED Pins I
Equivalent Output Resistance R

Gain = 1× VIN = 3.6 V, I

Gain = 1.5× VIN = 3.1 V, I

Gain = 2× VIN = 2.5 V, I
Regulated Output Voltage V

MATCH

V

MATCH7

V

MATCH6

VIN = 5.5 V, V

D1:D7(LKG)

OUT

VIN = 3 V, gain = 2×, I

OUT(REG)

= 0.4 V 2.0 %

D1:D7

= 0.4 V 1.5 %

D2:D7

= 2.5 V, Bit nSTBY = 1 0.5 A

D1:D7

= 100 mA 0.5 Ω

OUT

= 100 mA 3.0 Ω

OUT

= 100 mA 3.8 Ω

OUT

= 10 mA 4.3 4.9 5.5 V

OUT

AUTOMATIC GAIN SELECTION

Minimum Voltage

Gain Increases V
Minimum Current Sink Headroom

Decrease V

HR(UP)

IDX = I

V

HR(MIN)

until the gain switches up 162 200 276 mV

D1:D7

× 95% 180 mV

DX(MAX )

Voltage
Gain Delay t

GAIN

The delay after gain has changed and
before gain is allowed to change again

AMBIENT LIGHT SENSING

COMPARATORS
Ambient Light Sensor Current I

CMP_IN = VD6 = 2.8 V, Bit CMP2_SEL = 1 0.70 1.08 1.33 mA

ALS

DAC Bit Step

Threshold L2 Level I

Threshold L3 Level I

I

L2BIT

I

L3BIT

L2BIT

L3BIT

= I

/250 4.3 A

ALS

= I

/2000 0.54 A

ALS

= 0.4 V, Capacitor C1 = 1 F, Capacitor C2 = 1 F,

D1:D7

= 0 mA,

4.5 7.2 mA

100 s

Rev. A | Page 3 of 52

ADP8863

SDA

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

FAULT PROTECTION

Start-Up Charging Current Source ISS V
Output Voltage Threshold V

Exit Soft Start V
Short-Circuit Protection V

Output Overvoltage Protection V

OUT

OUT(START)

V

OUT(SC)

OVP

Activation Level 5.8 V
OVP Recovery Hysteresis V

OVP(HYS)

Thermal Shutdown

Threshold TSD 150 °C
Hysteresis TSD

Isolation from Input to Output

(HYS)

VIN = 5.5 V, V

I

OUTLKG

During Fault

Time to Validate a Fault t

2 s

FAULT

I2C INTERFACE

Operating V

Volt age V

DDIO

5.5 V

DDIO

Logic Low Input2 VIL V
Logic High Input3 VIH V

I2C TIMING SPECIFICATIONS Guaranteed by design

20 s

Delay from Reset Deassertion to

2

C Access

I
SCL Frequency f
SCL High Time t
SCL Low Time t

t

RESET

400 kHz

SCL

0.6 s

HIGH

1.3 s

LOW

Setup Time

Data t

Repeated Start t

Stop Condition t

100 ns

SU, DAT

0.6 s

SU, STA

0.6 s

SU, STO

Hold Time

Data t

Start/Repeated Start t
Bus Free Time (Stop and Start

0 0.9 s

HD, DAT

0.6 s

HD, STA

t

1.3 s

BUF

Conditions)
Rise Time (SCL and SDA) tR 20 + 0.1 CB 300 ns
Fall Time (SCL and SDA) tF 20 + 0.1 CB 300 ns
Pulse Width of Suppressed Spike tSP 0 50 ns

Figure 16

B

Capacitive Load per Bus Line C

1

Current source 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 input voltage. See in the section for typical values over operating ranges. Figure 16

3

VIH is a function of the input voltage. See in the section for typical values over operating ranges.

= 3.6 V, V

IN

V

rising 0.92 × VIN V

OUT

falling 0.55 × VIN V

OUT

= 0.8 × VIN 2.5 3.75 5.5 mA

OUT

500 mV

20 °C

= 0 V, Bit nSTBY = 0 1.5 A

OUT

= 3.6 V 0.6 V

IN

= 3.6 V 1.30 V

IN

400 pF

Typical Performance Characteristics

Typical Performance Characteristics

I2C TIMING DIAGRAM

SCL

S

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

t

LOW

t

R

t

HD, DAT

t

SU, DAT

t

HIGH

Figure 2. I

t

F

t

F

t

SU, STA

2

C Interface Timing Diagram

Sr

Rev. A | Page 4 of 52

t

HD, STA

t

SP

t

SU, STO

t

R

t

BUF

P S

08392-002

ADP8863

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

VIN, VOUT −0.3 V to +6 V

D1, D2, D3, D4, D5, D6, and D7 −0.3 V to +6 V

CMP_IN −0.3 V to +6 V

nINT, nRST, SCL, and SDA −0.3 V to +6 V

Output Short-Circuit Duration Indefinite

Operating Ambient Temperature Range –40°C to +85°C1

Operating Junction Temperature Range –40°C to +125°C

Storage Temperature Range –65°C to +150°C

Soldering Conditions JEDEC J-STD-020

ESD (Electrostatic Discharge)

Human Body Model (HBM) ±3 kV
Charged Device Model (CDM) ±1.5 kV

1

The maximum operating junction temperature (T

over the maximum operating ambient temperature (T
Maximum Temperature Ranges section for more information.

) takes precedence

J(MAX)

). See the

A(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.

Absolute maximum ratings apply individually only, not in

combination. Unless otherwise specified, all voltages are

referenced to ground.

MAXIMUM TEMPERATURE RANGES

The maximum operating junction temperature (T
precedence over the maximum operating ambient temperature
(T

). Therefore, in situations where the ADP8863 is

A(MAX)

exposed to poor thermal resistance and high power dissipation
(P

), the maximum ambient temperature may need to be

D

derated. In these cases, the maximum ambient temperature can
be calculated with the following equation:

T

A(MAX)

= T

J(MAX)

− (θJA × P

D(MAX)

)

J(MAX)

) takes

THERMAL RESISTANCE

θJA (junction to air) is specified for the worst-case conditions,
that is, a device soldered in a circuit board for surface-mount
packages. The θ

, θJB (junction to board), and θJC (junction to case)

JA

are determined according to JESD51-9 on a 4-layer printed
circuit board (PCB) with natural convection cooling. For the
LFCSP package, the exposed pad must be soldered to GND.

Table 3. Thermal Resistance

Package Type θJA θ

θ

JB

Unit

JC

WLCSP 48 9 N/A1 °C/W
LFCSP 49.5 N/A1 5.3 °C/W

1

N/A stands for not applicable.

ESD CAUTION

Rev. A | Page 5 of 52

ADP8863

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

1

_IN

D5

D4

CMP

D6

19

20

1

D3

2

D2

3

D1

4

SCL

5

nRST

NOTES

1. CONNECT THE EXPOSED PADDLE
TO GND1 AND/OR GND2.

TOP VIEW

(Not to Scale)

6

7

SDA

nINT

D7
16

18

17

9

8

10

C1–

C2–

GND2

Figure 3. LFCSP Pin Configuration

15 GND1
14

VIN

13

VOUT

12

C2+

11

C1+

08392-003

A

B

C

GND2

D

nRST

E

Figure 4. WLCSP Pin Configuration

Table 4. Pin Function Descriptions

Pin No.

LFCSP WLCSP

Mnemonic Description

14 A3 VIN Input Voltage, 2.5 V to 5.5 V.
3 D3 D1 LED Sink 1.
2 E3 D2 LED Sink 2.
1 E4 D3 LED Sink 3.
20 D4 D4 LED Sink 4.
19 C4 D5 LED Sink 5.
17 B4 D6 LED Sink 6. This pin can also be selected as a comparator input for the second phototransistor.
16 B3 D7 LED Sink 7.
18 C3 CMP_IN

Comparator Input for Phototransistor. When using this function, a capacitor (0.1 µF recommended)

must be connected from this pin to ground.
13 A2 VOUT Charge Pump Output.
11 A1 C1+ Charge Pump C1+.
9 C1 C1−

Charge Pump C1−.
12 B1 C2+ Charge Pump C2+.
10 B2 C2− Charge Pump C2−.
15 A4 GND1 Ground. Connect the exposed pad to GND1 and/or GND2.
8 D1 GND2 Ground. Connect the exposed pad to GND1 and/or GND2.
6 D2 nINT

Processor Interrupt (Active Low). Requires an external pull-up resistor. If this pin is not used, it

can be left floating.
5 E1 nRST

Hardware Reset (Active Low). This pin resets the device to the default conditions. If not used,

this pin must be tied above V

IH(MIN)

.
7 C2 SDA I2C Serial Data. Requires an external pull-up resistor.
4 E2 SCL I2C Clock. Requires an external pull-up resistor.
21 NA EPAD Exposed Paddle. Connect the exposed paddle to GND1 and/or GND2.

234

C1+

VOUT

C2+

C2–

C1–

SDA

nINT

SCL

TOP VIEW

(BALL SIDE DOWN)

Not to Scale

VIN

D7 D6

CMP_IN

D1

D2

GND1

D5

D4

D3

08392-052

Rev. A | Page 6 of 52

ADP8863

TYPICAL PERFORMANCE CHARACTERISTICS

VIN = 3.6 V, SCL = 2.7 V, SDA = 2.7 V, nRST = 2.7 V, V
T

= 25°C, unless otherwise noted.

A

2.0
I

= NO LOAD

OUT

1.8

1.6

1.4

1.2

1.0

(mA)

Q

I

0.8

0.6

0.4

0.2

0

1.52.02.53.03.54.04.55.05.5
VIN (V)

Figure 5. Typical Quiescent Current, G = 1×

5.0

4.5

4.0

3.5

3.0

2.5

(mA)

Q

I

2.0

1.5

1.0

0.5

0

1.52.02.53.03.54.04.55.05.5
VIN (V)

Figure 6. Typical Quiescent Current, G = 2×, I

10

1

–40°C
+25°C
+85°C
+105°C

I

= NO LOAD

OUT

–40°C
+25°C
+85°C
+105°C

Q(ACTIVE)

SCL = SDA = 0V
nRST = 2. 7V

= 0.4 V, CIN = 1 F, Capacitor C1 = 1 F, Capacitor C2 = 1 F, C

D1:D7

35

VIN = 3.6V

= 30mA

I

D1:D7

30

25

20

(mA)

OUT

I

15

10

5

0

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

08392-004

VHR (V)

Figure 8. Typical Diode Current vs. Current Sink Headroom Voltage (VHR)

35

V

= 0.4V

D1:D7

34

33

32

31

(mA)

30

OUT

I

29

28

27

26

25

2.0 5.52.5 3.0 3.5 4.0 4.5 5.0

08392-005

VIN (V)

Figure 9. Typical Diode Matching vs. V

6

–40°C
+25°C
+85°C

5

+105°C

4

OUT

IN

VIN = 3.6V

= 30mA

I

D1:D7

= 1 F,

D1
D2
D3
D4
D5
D6
D7

08392-007

D1
D2
D3
D4
D5
D6
D7

08392-008

(µA)

Q

I

0.1

0.01

0.001

–40°C
+25°C
+85°C
+105°C

10 23456

VIN (V)

08392-006

Figure 7. Typical Standby IQ vs. VIN

Rev. A | Page 7 of 52

3

MISMATCH (%)

2

1

0

0.2 2.01.81.61.41.21.00.80.60.4
VHR (V)

08392-009

Figure 10. Typical Diode Matching vs. Current Sink Headroom Voltage (VHR)

ADP8863

35

VIN = 3.6V

= 30mA

I

D1:D7

30

25

20

(mA)

OUT

15

I

10

5

0

00.2 2.01.81.61.41.21.00.80.60.4
VHR (V)

–40°C
+25°C
+85°C
+105°C

Figure 11. Typical Diode Current vs. Current Sink Headroom Voltage (VHR)

1

VIN = 3.6V
V

= 0.40V

D1:D7

0

–1

–2

–3

DEVIATIO N ( %)

OUT

I

–4

–5

–6

–40 –10 20 50 80 110

JUNCTION TEM P ERAT URE (°C)

Figure 12. Typical Change In Diode Current vs. Temperature

7

I

= 100mA

OUT

6

5

4

(Ω)

OUT

3

R

2

G = 2× @ V

G = 1.5× @ V

= 2.5V

IN

IN

= 3V

08392-010

08392-011

1.0

0.9

0.8

0.7

0.6

(Ω)

0.5

OUT

R

0.4

0.3

0.2

0.1

0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

Figure 14. Typical R

VIN (V)

(G = 1×) vs. V

OUT

I

OUT

IN

10

V

= 80% OF V

OUT

9

8

7

6

(mA)

5

OUT

I

4

3

2

1

0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

IN

VIN (V)

Figure 15. Typical Output Soft Start Current, I

1.4

1.2

1.0

0.8

0.6

THRESHOLD (V)

0.4

VIH @ +25°C
VIH @ +85°C
VIH @ –40°C

= 100mA

–40°C
+25°C
+85°C
+105°C

08392-013

–40°C
+25°C
+85°C
+105°C

08392-014

SS

VIL @ +25°C
VIL @ +85°C
VIL @ –40°C

1

0

–40 –20 0 20 40 60 80 100

G = 1× @ VIN = 3.6V

TEMPERATURE (°C)

Figure 13. R

vs. Temperature

OUT

08392-012

Rev. A | Page 8 of 52

0.2

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)

Figure 16. Typical I2C Thresholds, VIH and VIL

08392-015

ADP8863

1.4

1.3

1.2

1.1

(mA)

ALS

1.0

I

0.9

0.8

0.7

3.02.5 3.5 4.0 4.5 5.0 5.5
VIN (V)

Figure 17. Typical ALS Current, I

5.5
VIN = 3V
GAIN = 2×

5.4
I

= 10mA

OUT

5.3

5.2

5.1

(V)

5.0

OUT

V

4.9

4.8

4.7

4.6

4.5

–10–40 20 50 80 110

JUNCTION TE MPERATURE (° C)

Figure 18. Typical Regulated Output Voltage (V

6.0

5.8

(V)

5.6

OUT

V

OVP THRESHOLD

ALS

–40°C
+25°C
+85°C
+105°C

OUT(REG)

08392-035

08392-016

)

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

2.5 5.55.04.54.03.53.0

100

90

80

70

60

50

40

EFFICIENCY (%)

30

20

10

0

2.5 5.55.04.54.03.53.0

1

2

I

= 140mA, Vf = 3.1V

OUT

I

= 210mA, Vf = 3.2V

OUT

VIN (V)

Figure 20. Typical Efficiency (Low Vf Diode)

I

= 140mA, Vf = 3.85V

OUT

I

= 210mA, Vf = 4.25V

OUT

VIN (V)

Figure 21. Typical Efficiency (High Vf Diode)

T

VIN (AC-COUPLED) 50 mV /DIV

V

(AC-COUPLED) 50mV/ DI V

OUT

450

400

350

300

250

(mA)

IN

200

I

150

100

50

0

450

400

350

300

250

(mA)

IN

200

I

150

100

50

0

08392-018

08392-019

5.4

OVP RECOVE RY

5.2

–10–40 20 50 80 110

JUNCTION TE MPERATURE (° C)

Figure 19. Typical Overvoltage Protection (OVP) Threshold

08392-017

Rev. A | Page 9 of 52

3

CIN = 1µF, C
V
I

IN

OUT

= 3.6V

= 120mA

IIN (AC-COUPLED) 10mA/DIV

= 1µF, C1 = 1µF, C2 = 1µF

OUT

Figure 22. Typical Operating Waveforms, G = 1×

500ns/DIV

08392-020

ADP8863

T

VIN (AC-COUPLED) 50mV /DIV

1

V

(AC-COUPLED) 50 mV /DIV

OUT

2

CIN = 10pF, C
C1 = 1µF, C2 = 1µF

= 3.7V

V

IN

= 30mA

I

OUT

(ONE DIODE AT
MAX CURRENT)

2

OUT

= 1µF

V

(1V/DIV)

OUT

3

CIN = 1µF, C
V
I

IN

OUT

= 3.0V

= 120mA

IIN (AC-COUPLED) 10mA/DIV

= 1µF, C1 = 1µF, C2 = 1µF

OUT

Figure 23. Typical Operating Waveforms, G = 1.5×

T

VIN (AC-COUPLED) 50mV /DIV

1

V

(AC-COUPLED) 50 mV /DIV

OUT

2

3

CIN = 1µF, C
V
I

IN

OUT

= 2.5V

= 120mA

IIN (AC-COUPLED) 10mA/DIV

= 1µF, C1 = 1µF, C2 = 1µF

OUT

Figure 24. Typical Operating Waveforms, G = 2×

500ns/DIV

500ns/DIV

IIN (10mA/DIV)

4

08392-021

I

OUT

(10mA/DIV)

100µs/DIV

08392-023

Figure 25. Typical Start-Up Waveform

08392-022

Rev. A | Page 10 of 52

ADP8863

THEORY OF OPERATION

The ADP8863 combines a powerful LED charge pump driver
with independent control of up to seven LEDs. These LED
drivers can sink up to 30 mA (typical) on six channels. The
seventh LED can also be driven to 60 mA (typical). All LEDs
can be individually programmed or combined into a group to

operate backlight LEDs. A full set of safety features, including
short-circuit, overvoltage, and overtemperature protection with
input-to-output isolation, allows for a robust and safe design.
The integrated soft start limits inrush currents at startup, restart
attempts, and gain transitions.

V

ALS

OPTIONAL

PHOTOSENSOR

D4 D5

ID4 ID5

EN

SENSOR

VIN

LIGHT

LOGIC

D6 D7 CMP_IN

GAIN

SELECT

GND2

LOGIC

CHARGE

PUMP

LOGIC

ID6

V

REFS

I

REFS

ID7

CLK

GND1

PHOTOSENSOR

CONVERSION

SOFT ST ART

CHARGE

PUMP

(1×, 1.5×, 2×)

V

IN

I

SS

VOUT

C

OUT

C1+

C1

1µF
C1–
C2+

C2

1µF
C2–

08392-024

VBAT

VDDIO

nRST

SCL

SDA

nINT

VIN

C

IN

D1

ID1

ID2

VIN

STNDBY

NOISE FILTER

50µs

RESET

2

I

C

LOGIC

D2 D3

ID3

UVLO

STANDBY

SWITCH CONTROL
CURRENT SINK CONTROL

Figure 26. Detailed Block Diagram

Rev. A | Page 11 of 52

ADP8863

V

POWER STAGE

Because typical white LEDs require up to 4 V to drive them,
some form of boosting is required over the typical variation in
battery voltage. The ADP8863 accomplishes this with a high
efficiency charge pump capable of producing a maximum I
of 240 mA over the entire input voltage range (2.5 V to 5.5 V).
Charge pumps use the basic principle that a capacitor stores
charge based on the voltage applied to it, as shown in the
following equation:

Q = C × V (1)

By charging the capacitors in different configurations, the
charge, and therefore the gain, can be optimized to deliver the
voltage required to power the LEDs. Because a fixed charging
and discharging combination must be used, only certain
multiples of gain are available. The ADP8863 is capable of
automatically optimizing the gain (G) from 1×, 1.5×, and 2×.
These gains are accomplished with two capacitors (labeled C1
and C2 in Figure 26) and an internal switching network.

In G = 1× mode, the switches are configured to pass VIN
directly to VOUT. In this mode, several switches are connected
in parallel to minimize the resistive drop from input to output.
In G = 1.5× and 2× modes, the switches alternatively charge
from the battery and discharge into the output. For G = 1.5×,
the capacitors are charged from V
V

in parallel. For G = 2×, the capacitors are charged from VIN

OUT

in series and are discharged to

IN

OUT

in parallel and are discharged to V
modes, the switches are opened and the output is physically
isolated from the input.

Automatic Gain Selection

Each LED that is driven requires a current source. The voltage
on this current source must be greater than a minimum head­room voltage (200 mV typical) to maintain accurate current
regulation. The gain is automatically selected based on the
minimum voltage (V

) at all of the current sources. At startup,

DX

the device is placed into G = 1× mode and the output charges
to V

. If any VDX level is less than the required headroom

IN

(200 mV), the gain is increased to the next step (G = 1.5×).
A 100 s delay is allowed for the output to stabilize prior to
the next gain switching decision. If there remains insufficient
current sink headroom, then the gain is increased again to 2×.
Conversely, to optimize efficiency, it is not desirable for the
output voltage to be too high. Therefore, the gain reduces when
the headroom voltage is great enough. This point (labeled
V

in Figure 27) is internally calculated to ensure that the

DMAX

lower gain still results in ample headroom for all the current
sinks. The entire cycle is illustrated in Figure 27.

Note that the gain selection criteria apply only to active current
sources. If current sources have been deactivated through an

2

I

C command (for example, only five LEDs are used), then the

voltages on the deactivated current sources are ignored.

in parallel. In certain fault

OUT

STANDBY

EXIT

STARTUP

G = 1

G = 1.5

G = 2

NOTES

1.

IS THE CALCULATED GAIN DOWN TRANSITION PO INT.

DMAX

EXIT ST ANDBY

1

100µs (TYP)

1

WAIT

100µs (TYP)

100µs (TYP)

Figure 27. State Diagram for Automatic Gain Selection

STARTUP:

CHARGE

V

IN

0

VOUT > V

WAIT

WAIT

TO V

OUT

OUT(START)

0

MIN (V

1

1

1

D1:D7

MIN (V

MIN (V

) < V

D1:D7

D1:D7

HR(UP)

) < V

0

) < V

HR(UP)

DMAX

0

MIN (V

0

D1:D7

) > V

DMAX

08392-025

Rev. A | Page 12 of 52

ADP8863

Soft Start Feature

At startup (either from UVLO activation or fault/standby
recovery), the output is first charged by I
until it reaches about 92% of V

. This soft start feature reduces

IN

(3.75 mA typical)

SS

the inrush current that is otherwise present when the output
capacitance is initially charged to V

. When this point is

IN

reached, the controller enters G = 1× mode. If the output
voltage is not sufficient, then the automatic gain selection
determines the optimal point as defined in the Automatic Gain
Selection section.

OPERATING MODES

There are four different operating modes: active, standby,
shutdown, and reset.

Active Mode

In active mode, all circuits are powered up and in a fully
operational state. This mode is entered when Bit nSTBY (in
Register MDCR) is set to 1.

Standby Mode

Standby mode disables all circuitry except for the I2C receivers.
Current consumption is reduced to less than 1 A. This mode is
entered when the nSTBY bit is set to 0 or when the nRST pin is
held low for more than 100 s (maximum). When standby is
exited, a soft start sequence is performed.

Shutdown Mode

Shutdown mode disables all circuitry, including the I2C receivers.
Shutdown occurs when V
When V

rises above V

IN

is below the undervoltage thresholds.

IN

(2.05 V typical), all registers are

IN(START)

reset and the part is placed into standby mode.

Reset Mode

In reset mode, all registers are set to their default values and
the part is placed into standby. There are two ways to reset the
part: by power-on reset (POR) or using the nRST pin. POR is
activated any time that the part exits shutdown mode. After a
POR sequence is complete, the part automatically enters
standby mode.

After startup, the part can be reset by pulling the nRST pin low.
As long as the nRST pin is low, the part is held in a standby
state, but no I

2

C commands are acknowledged (all registers are
kept at their default values). After releasing the nRST pin, all
registers remain at their default values, and the part remains in
standby; however, the part does accept I

2

C commands.

The nRST pin has a 50 s (typical) noise filter to prevent inad­vertent activation of the reset function. The nRST pin must be
held low for this entire time to activate reset.

The operating modes function according to the timing diagram
in Figure 28.

SHUTDOWN

V

STANDBY

nRST

V

OUT

IN

VINCROSSES ~2.05V AND TRIGGERS POWER-ON RESET

BIT nSTBY IN REGISTER
MDCR GOES LOW

~100µs DELAY BETWEEN POWER-UP AND

2

C COMMANDS CAN BE RECEIVED

WHEN I

25µs TO 100µs NOISE FILTER

~3.75mA CHARGES
V

V

IN

TO VINLEVEL

OUT

1×

10µs 100µs

1.5×

2×

nRST MUST BE HIGH FOR 20µs (MAX)
BEFORE SENDING I

nRST IS LOW, WHICH FORCESSTANDBY
LOW AND RESETS ALL I

GAIN CHANGES OCCUR ONLY W HE N NECESSARY,
BUT HAVE A MIN TIME BEFORE CHANGING

2

CCOMMANDS

2

CREGISTERS

SOFT STARTSOFT START

08392-026

Figure 28. Typical Timing Diagram

Rev. A | Page 13 of 52

ADP8863

LED GROUPINGS

Each LED can respond individually or be grouped together
into the backlight controls. By default, all LEDs are set to be
part of the backlight. This is changed by setting Bits[6:0] in
Register 0x05. LEDs that are set up as independent sinks can
be enabled individually in Register 0x10. They can also all be
enabled simultaneously via the SIS_EN bit in Register 0x01.
Any LEDs configured for the backlight can only be enabled
via the BL_EN bit in Register 0x01.

LED CURRENT SETTINGS

Any of the LED outputs (Pin D1 to Pin D7) can be used to
drive any color of LED at 0 mA to 30 mA, provided that the
LED’s Vf is less than 4.1 V. Additionally, the D7 sink can regu­late up to 60 mA. The current settings are determined by a
7-bit code programmed by the user into Register 0x14 through
Register 0x1A (for the independent sinks) and Register 0x09 to
Register 0x0E (for the backlight sinks). The 7-bit resolution
allows the user to set the LED to one of 128 different levels.

The ADP8863 can implement two distinct algorithms to
achieve a linear or a nonlinear relationship between input
code and diode output current. The law and SC_LAW bits
in Register 0x04 and Register 0x0F, respectively, are used to
change between these algorithms.

By default, the ADP8863 uses a linear algorithm (law and
SC_LAW = 00), where the LED current increases linearly for
a corresponding increase in input code. LED current (in
milliamperes) is determined by the following equation:

LED Current (mA) = Code × (Full-Scale Current/127) (2)

where:

Code is the input code programmed by the user.
Full-Scale Current is the maximum sink current allowed per

LED (typically 30 mA).

The ADP8863 can also implement a nonlinear (square
approximation) relationship between input code and LED
current. In this case (law and SC_LAW = 01, 10, or 11), the LED
current (in milliamperes) is determined by the following
equation:

2

⎛
⎜

)mA(

×=

CodeCurrentLED

⎜
⎝

−

CurrentScaleFull

127

Figure 29 shows the LED current level vs. input code for both
the linear and square law algorithms.

⎞
⎟

(3)

⎟
⎠

30

25

20

15

10

LED CURRENT (mA)

5

0

0 32 64 96 128

LINEAR

SQUARE

CODE

Figure 29. LED Current vs. Input Code

08392-027

AUTOMATED FADE IN AND FADE OUT

The LED drivers are easily configured for automated fade in
and fade out. Sixteen fade in and fade out rates can be selected
via the I

0.0 sec to 5.5 sec (per full-scale current, either 30 mA or 60 mA).
The backlight LEDs have separate fade in and fade out time
controls from the independent sink LEDs.

Table 5. Available Fade In and Fade Out Rates

Code Fade Rate (in sec per Full-Scale Current)

0000 0.0 (disabled)
0001 0.3
0010 0.6
0011 0.9
0100 1.2
0101 1.5
0110 1.8
0111 2.1
1000 2.4
1001 2.7
1010 3.0
1011 3.5
1100 4.0
1101 4.5
1110 5.0
1111 5.5

The fade profile is based on the transfer law selected (linear,
square, Cubic 10, or Cubic 11) and the delta between the actual
current and the target current. Smaller changes in current
reduce the fade time. For linear and square law fades, the fade
time is given by

where the Fade Rate is shown in Tabl e 5.

2

C interface. Fade in and fade out rates range from

Fade Time = Fade Rate × (Code/127) (4)

Rev. A | Page 14 of 52

ADP8863

The Cubic 10 and Cubic 11 laws also use the square law LED
currents derived from Equation 3; however, the time between
each step is varied to produce a steeper slope at higher currents
and a shallower slope at lower currents (see Figure 30).

30

25

LINEAR

20

15

CURRENT (mA)

10

5

0

00.750.500.25

Figure 30. Comparison of the Dimming Transfers Laws

SQUARE

UNIT FADE TIME

CUBIC 11

CUBIC 10

1.00

08392-028

Each LED can be enabled independently and has its own
current level, but all LEDs share the same fade in rates, fade out
rates, and fade law.

INDEPENDENT SINK CONTROL

Each of the seven LEDs can be configured (in Register 0x05) to
operate as either part of the backlight or to operate as an indepen­dent sink current (ISC). Each ISC can be enabled independently
and has its own current level. All ISCs share the same fade in
rates, fade out rates, and fade law.

The ISCs have additional timers to facilitate blinking functions.
A shared on timer (SCON) in conjunction with the off timer of
each ISC (SC1OFF, SC2OFF, SC3OFF, SC4OFF, SC5OFF, SC6OFF,
and SC7OFF) allows the LED current sinks to be configured in
various blinking modes. The on timer can be set to one of four
different settings: 0.2 sec, 0.6 sec, 0.8 sec, or 1.2 sec. The off
timers have four different settings: disabled, 0.6 sec, 1.2 sec, and

1.8 sec. Blink mode is activated by setting the off timers to any
setting other than disabled.

Program all fade, on, and off timers before enabling any of the
LED current sinks. If ISCx is on during a blink cycle and
SCx_EN is cleared, the LED turns off (or fades to off if fade out
is enabled). If ISCx is off during a blink cycle and SCx_EN is
cleared, it stays off.

Rev. A | Page 15 of 52

ISCx

ON TIME ON TIME

FADE-IN FADE-OUT FADE-IN FADE-OUT

MAX

OFF

TIME

SCx_EN

SET BY USER

Figure 31. Independent Sink Blink Mode with Fading

OFF

TIME

RGB COLOR GENERATION

The ADP8863 is easily programmed to generate any color with
an RGB LED. To configure this feature, connect each LED in a
standard RGB diode to a separate driver on the ADP8863.
Because each channel can be programmed for a different
current level, setting the currents for all three LEDs generates
the desired color. To set the current levels, use a simple RGB
color selector (see Figure 32).

08392-036

Figure 32. Standard RGB Color Generator

The example in Figure 32 shows a color of green, which is gener­ated with a red content of 18 (out of 255), a green content of
190, and a blue content of 96. All numbers are out of a maximum
of 255. Thus, the percentage of red is 7.1%, the percentage of
green is 74.5%, and the percentage of blue is 37.6%. To generate
the color with the ADP8863, scale this value to each of the current
drivers.

AUTOMATED RGB COLOR FADES

The ADP8863 is easily programmed to cycle through RGB
generated colors. This can be either a repeating or a random
pattern of one color fading into the other. To execute this cycle
autonomously, set up the RGB LEDs as described in the RGB
Color Generation section and program the on, off, fading times,
and current intensities. Adjusting the fading time in particular
can create any pattern from a fast, striking effect to a soothing
slow color change.

08392-029

ADP8863

A

Y

BACKLIGHT OPERATING LEVELS

Backlight brightness control operates at three distinct levels:
daylight (L1), office (L2), and dark (L3). The BLV bits in
Register 0x04 control the specific level at which the backlight
operates. These bits can be changed manually or, if in automatic
mode (CMP_AUTOEN is set high in Register 0x01), by the
ambient light sensor (see the Ambient Light Sensing section).

By default, the backlight operates at daylight level (BLV = 00),
where the maximum brightness is set using Register 0x09
(BLMX1). A daylight dim setting can also be set using Register
0x0A (BLDM1). When operating at office level (BLV = 01), the
backlight maximum and dim brightness settings are set using
Register 0x0B (BLMX2) and Register 0x0C (BLDM2). When
operating at the dark level (BLV = 10), the backlight maximum
and dim brightness settings are set using Register 0x0D (BLMX3)
and Register 0x0E (BLDM3).

D

30mA

BACKLIGHT CURRENT

0

LIGHT (L 1) OFFI CE (L 2) DARK (L 3)

DAYLIGHT_MAX

OFFICE_MAX

DARK_MAX

DAYLIGHT_DIM

OFFICE_DIM

DARK_DIM

BACKLIGHT OPERATING LEVELS

Figure 33. Backlight Operating Levels

BACKLIGHT TURN ON/TURN OFF/DIM

With the device in active mode (nSTBY = 1), the backlight can
be turned on using the BL_EN bit in Register 0x01. Before
turning on the backlight, select 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 34. Backlight Turn On/Turn Off

While the backlight is on (BL_EN = 1), the user can change to
the dim setting by programming DIM_EN = 1 in Register 0x01.
If DIM_EN = 0, the backlight reverts to its maximum setting.

8392-038

BACKLIGHT

CURRENT

MAX

DIM

BL_EN = 1

DIM_EN = 1 DIM_EN = 0 BL_ EN = 0

8392-039

Figure 35. Backlight Turn On/Dim/Turn Off

The maximum and dim settings can be set from 0 mA to 30 mA;
therefore, it is possible to program a dim setting that is greater
than a maximum setting. For normal expected operation,
ensure that the dim setting is programmed to be less than the
maximum setting.

AUTOMATIC DIM AND TURN OFF TIMERS

The user can program the backlight to dim automatically by
using the DIMT bits in Register 0x07. The dim timer has 127
settings ranging from 1 sec to 127 sec. Program the dim timer
(DIMT) 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 enters its dim

08392-037

setting.

BACKLIGHT

CURRENT

MAX

DIM

DIM TIMER

RUNNING

BL_EN = 1 BL_EN = 0DIM_EN = 1 DIM_EN = 0 DIM_E N = 1

SET BY USER
SET BY INTERNAL STATEMACHINE

DIM TIMER

RUNNING

Figure 36. Dim Timer

If the user clears the DIM_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 enters its dim setting. 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 OFFT bits in Register 0x06. The off timer has
127 settings ranging from 1 sec to 127 sec. Program the off
timer (OFFT) before turning on the backlight. If BL_EN = 1,
the backlight turns on to its maximum setting and the off timer

8392-040

Rev. A | Page 16 of 52