A8530EESTR-T - Allegro Microsystems

VBATT

CIN

1 μFD1

LED1

LED2

LED3

LED4

LED5

LED6

ENM

ENF

VOUT

GND

VIN

C2+

C2–

ISET

RSET

C1+

C1–

On/Off and

Dimming

Control

A8530

D1-D4 Main; D5-D6 Flash

(max)+0.2V, V

= LED forward drop

Approximate Scale 1:1

Figure 4. High efficiency current sink

Typical Applications

VBATT

2.7 to 5.5 V

CIN

4.7 µF

COUT

4.7 µF

1 µF

LED1

LED2

LED3

LED4

LED5

LED6

ENM

ENF

VOUT

GND

VIN

C2+

C2–

ISET

RSET

C1+

C1–

A8530

On/Off and

Dimming

Control

VBATT

2.7 to 5.5 V

CIN

4.7 µF

COUT

4.7 µF

1 µF

LED1

LED2

LED3

LED4

LED5

LED6

ENM

ENF

VOUT

GND

VIN

C2+

C2–

ISET

RSET

C1+

C1–

A8530

D1-D4 Backlight; D5-D6 Flash

On/Off and

Dimming

Control

Figure 2. 3 × 100 mA flash

Figure 3. 320 mA flash

Description

The A8530 high efficiency charge pump ICs offer a simple,

low-cost white LED driver solution for driving four display

backlight and two flash/torch/video mode white LEDs. Using

a proprietary control scheme (1×, 1.5×, and 2×), the A8530

can deliver well-matched LED current while maintaining the

highest efficiency and low EMI. The LED current is regulated

over the entire range of Li+ battery voltage to provide uniform

intensity.

LED brightness and on/off can be controlled for 4 display

backlight LEDs and 2 flash/torch LEDs through 2 single-wire

serial interface pins.

The A8530 is available in a very thin profile (0.75 mm nominal

height) 3 mm× 3 mm QFN/MLP 16 pin package. Applications

include:

▪ White LED backlights for cellular phones, PDAs

▪ Digital cameras, camcorders

▪ Other portable device white LED backlighting

▪ 320 mA WLED flash/torch

8530-DS, Rev. 1

Features and Benefits

▪ Proprietary adaptive control scheme (1×, 1.5×, 2×)

▪ 0.5% typical LED current matching

▪ 2 separate serial interfaces for dimming control

▪ Drives up to 6 white LEDs (4 display backlight, 2 flash/torch)

▪ 30 mA per LED channel for display backlight

▪ 100 mA per LED channel for flash/torch backlight

▪ 320 mA total output current capability

▪ Low EMI design and soft-start function

▪ Short circuit, overvoltage, thermal shutdown protection

▪ 0.75 mm very thin profile, 3 mm × 3 mm package

Ultracompact 6-Channel Backlight

and Flash/Torch White LED Driver

Package: 16 pin QFN/MLP (suffix ES)

A8530

VBATT

2.7 to 5.5 V

CIN

4.7 µF

COUT

4.7 µF

1 µF

LED1

LED2

LED3

LED4

LED5

LED6

ENM

ENF

VOUT

GND

VIN

C2+

C2–

ISET

RSET

C1+

C1–

On/Off and

Dimming

Control

A8530

D1-D4 Backlight; D5-D6 Flash

Figure 1. 4 × 30 mA backlight with 2 × 100 mA flash

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Functional Block Diagram

Ab so lute Max i mum Rat ings

Input or Output Voltage

VIN, VOUT, C1+, C1– , C2+, C2– to GND ..................... –0.3 to 6 V

All other pins ..................................................... –0.3 to VIN + 0.3 V

VOUT Short Circuit to GND ....................................................Continuous

Operating Ambient Temperature, TA ..................................... –40°C to 85°C

Junction Temperature, TJ(max) .............................................................. 150°C

Storage Temperature, TS

................................................... –55°C to 150°C

IREF

+–

–

+–+–+–+–+–

Fractional Charge Pump

(1×, 1.5×, and 2×)

VIN

RSET

LED1

LED2

LED3

LED4

LED5

LED6

ENM

ENF

VOUT

C1+ C1 –C2+ C2–

ISET

GND

4.7 µF

1 µF

4.7 µF

CIN COUT

Minimum Select

Current Mirror

Control, Clock,

and Reference

Use the following complete part number when ordering:

Part Number Packaging* Package Type

A8530EESTR-T 7-in. reel, 1500 pieces/reel ES, 3 × 3 mm MLP-16

*Contact Allegro for additional packing options.

Device package is lead (Pb) free, with 100% matte tin leadframe

plating.

Package Thermal Characteristics

RθJA = 47 °C/W, on a 4-layer board based on JEDEC spec

Additional information is available on the Allegro Web site.

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Terminal List Table

GND

LED1

EP LED2

LED3

C2+

VOUT

ISET

ENF

C1+

C2–

VIN

C1–

ENM

LED6

LED5

LED4

ES Package

(Top View)

Pin-out Diagram

Name Number Function

C1– 13 Negative terminal of capacitor C1. Connect capacitor C1 between C1+ and C1–.

C1+ 16 Positive terminal of capacitor C1.

C2– 15 Negative terminal of capacitor C2

C2+ 1 Positive terminal of capacitor C2. Connect capacitor C2 between C2+ and C2–.

ENF 4 Enable and dimming control input for flash/torch.

ENM 5 Enable and dimming control input for display backlight.

EP – Exposed metal pad on bottom side. Connect this to ground plane for better thermal performance.

GND 12 Ground.

ISET 3 Connect RSET resistor to ground to set desired constant current through backlight LEDs.

ILED(max) = 220 x 0.6 V / RSET

LED1, LED2,

LED3, and LED4

8, 9, 10,

and 11

Current sink for display backlight LEDs. If not used, connect to VOUT, but do not leave open. If left

open, the IC works in 2 × mode.

LED5 and LED6 6 and 7 Current sink for flash/torch LEDs. If not used, connect to VOUT, but do not leave open. If left open,

the IC works in 2 × mode.

VIN 14 Power supply voltage input.

VOUT 2 Charge pump output voltage source for display backlight and flash/torch LED anodes.

Connect a 4.7 F capacitor, COUT, between VOUT and GND (see figures 1 through 4).

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

ELECTRICAL CHARACTERISTICSa VIN = ENM = 3.6 V, ENF = GND, C1 = C2 = 1 F, CIN = COUT = 4.7 F, RSET = 6.49 k,

TA = –40°C to +85°C; typical values are at TA = 25°C; unless otherwise noted

Characteristics Symbol Test Conditions Min. Typ. Max. Units

Input Voltage Range VIN 2.7 – 5.5 V

Undervoltage Lockout Threshold VUVLO VIN falling 2.25 2.45 2.60 V

UVLO Hysteresis Window VUVLOHYS –60–mV

Quiescent Current IQ

Switching in 1.5 × or 2.0 × mode; TA = 25°C – 6 – mA

ENF = ENM = GND; TA = 25°C – 0.1 2 A

Soft-start Completion Time tss – 2.0 – ms

ISET Bias Voltage VISETBIAS – 0.6 – V

ISET Leakage in Shutdown VISETLKG – 0.01 1 A

ISET Current Range ISET 40 – 140 A

ISET to LEDx Current Ratio for LED1 through LED4 ILEDx/IISET 100% setting, ISET = 60 A – 220 – A/A

100% Output Current for LED5 and LED6 ILED56MAX Default 100% setting when ENF is enabled 92 100 108 mA

ILED Accuracy for LED1 through LED4bEILED14ERR ENF = GND, ENM = VIN – ±1.6 – %

LED Current Matching for LED1 through LED4cILED14 ENF = GND, ENM = VIN – ±0.5 – %

LED Current Matching for LED5 and LED6cILED56 ENF = VIN, ENM = GND, 100% – ±0.5 – %

Regulation Voltage at LEDx (1.5

× and 2

× modes) VREG ENF = ENM = VIN – 250 – mV

1x mode to 1.5x or 1.5x to 2x mode transition voltage at LEDx Vtrans VLEDx falling – 150 – mV

Transition–Dropout DeltadVdr Measured as Vtrans – Vdropout –40–mV

Open Loop Output ResistanceeROUT

1× mode (VIN – VOUT) / IOUT –1–

1.5× mode (1.5 × VIN – VOUT) / IOUT – 2.5 – 

2× mode (2 × VIN – VOUT) / IOUT –5–

LED Leakage in Shutdown VLEDLKG ENF = ENM = GND, VIN = 5.5 V – 0.01 1 A

Oscillator Frequency fosc – 1 – MHz

Output Overvoltage Protection (guaranteed by design) Vovp

Open circuit at any LED that is programmed

to be in the ON state – – 6.0 V

ENF and ENM Input High Threshold VIH Input high logic threshold 1.4 – – V

ENF and ENM Input Low Threshold VIL Input low logic threshold – – 0.4 V

Input High Current IIH VIH=VIN – – 1 A

Input Low Current IIL VIL= GND – – 1 A

ENM and ENF Pulse Low Time (figure 6) tLO 0.5 – 250 s

ENM and ENF Pulse High Time (figure 6) tHI 0.5 – – s

ENM and ENF Initial Pulse High Time (figure 6) tINIHI First ENM or ENF pulse after shutdown 50 – – s

Shutdown or Dimming Reset Delay tSHDN Falling edge of ENF and/or ENM – 0.5 – ms

Thermal Shutdown Threshold TTSD 20oC hysteresis – 165 – oC

aSpecifications for the range TA = –40°C to 85°C are guaranteed by design.

bILED accuracy is defined as ( ISET × 220 – ILEDAVG

) / (ISET × 220).

cLED current matching is defined as (ILEDx – ILEDAVG) / ILEDAVG

dDropout voltage Vdropout is defined as LEDx-to-GND voltage at which ILEDx drops 10% below the value of ILEDx when VLEDx = 300 mV.

eThe open loop output resistance, ROUT, for 1.5

× mode is measured when one of the LEDx pins is tied to ground or open (thus its voltage is always less

than 80 mV).

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Eff (%)

VIN

(V)

VIN

(V)

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

VIN

(V)

2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5

46810121416

SET

(kΩ)

ILED /Channel(mA)

RSET = 6.65 kΩ

RSET = 8.87 kΩ

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

ENx

(V)

= 3.1 V

= 10 mA

= 3.4 V

= 20 mA

= 3.2 V

= 50 mA

= 3.7 V

= 100 mA

Efficiency versus Supply Voltage

for LED1 through LED4, in parallel

Efficiency versus Supply Voltage

for LED5 and LED6, in parallel

Dimming on ENM

Enable Pulses versus Total Current, LED1 through LED4

RSET versus ILED

Performance Characteristics

Tests performed using application circuit shown in figure 1

TA = 25°C, VIN

= 3.6 V (unless otherwise noted)

Symbol Parameter Units/Division

C1 VENM 0.5 V

C2 ILED14 50 mA

t time 50 ms

ILED14

VENM

Logic Level

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

LED5-6 ON, 1.5× mode

VIN = 3.2 V, IOUT = 200 mA, VF = 3.1 V

Performance Characteristics

Tests performed using application circuit shown in figure 1

TA = 25°C, VIN

= 3.6 V (unless otherwise noted)

Symbol Parameter Units/Division

C3 VOUT Ripple 20 mV

C4 IIN Ripple 50 mA

t time 500 ns

IIN

VOUT

LED5-6 ON, 2× mode

VIN = 2.7 V, IOUT = 200 mA, VF = 3.1 V

Symbol Parameter Units/Division

C3 VOUT Ripple 20 mV

C4 IIN Ripple 50 mA

t time 500 ns

IIN

VOUT

LED1-4 ON, 1.5× mode

VIN = 3.6 V, IOUT = 80 mA, VF = 3.4 V

Symbol Parameter Units/Division

C3 VOUT Ripple 20 mV

C4 IIN Ripple 50 mA

t time 500 ns

IIN

VOUT

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Symbol Parameter Units/Division

C1 VENF and VENM 2.00 V

C2 VOUT 2.00 V

C3 IOUT 100 mA

t time 0.5 ms

Symbol Parameter Units/Division

C1 VENF and VENM 2.00 V

C2 VOUT 2.00 V

C3 IOUT 100 mA

t time 0.5 ms

Turn ON LED1-6 in 1X Mode

VIN = 4.0 V, IOUT = 280 mA

Turn ON LED1-6 in 2X mode

VIN = 2.7 V, IOUT = 280 mA

Performance Characteristics

Tests performed using application circuit shown in figure 1

TA = 25°C

Symbol Parameter Units/Division

C1 VENF and VENM 2.00 V

C2 VOUT 2.00 V

C3 IOUT 100 mA

t time 0.5 ms

VENF and VENM

VOUT

Turn ON LED1-6 in 1.5X Mode

VIN = 3.0 V, IOUT = 280 mA

IOUT

VOUT

IOUT

VOUT

IOUT

VENF and VENM

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

SHDN or

Dimming

Reset

tSHDN

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 5%

100% 90%

tHI

tLO

tSS

SHDN

tHI(Init)

IILED(1-4) or

IILED(5-6)

ENM (LED1-4) or

ENF (LED5-6)

12345 67891011

Application Information

Figure 6. Single-Wire Serial Dimming Control; at pins ENF and ENM.

Setting LED Current

Use the following formula to set the display backlight LED full

current (100%) using RSET on LED1 through LED4. The maxi-

mum current through one LED should not exceed 30 mA:

RSET = 0.6 V × 220 / ILEDx

where RSET is in Ω and ILEDx in amperes.

The default flash/torch current on LED5 and LED6 is set inter-

nally to 100 mA per channel. When both the display backlight

and the flash/torch LEDs are on, the maximum current output

from LED1 through LED4 is 30 mA per channel. The output cur-

rent of the flash/torch LEDs (LED5 and LED6) can be adjusted

by serial dimming at the ENF pin within 1 ms after ENF is pulled

high.

Transitions Between 1× and 1.5× or 2× Modes

The A8530 adaptively selects operating mode. When VIN is suf-

ficiently high to maintain VLEDx > 150 mV, the A8350 operates

in 1 × mode unless, as VIN drops, the LEDx nodes fall below

the 150 mV threshold. When VLEDx falls below 150 mV, the IC

enters 1.5× mode.

When the A8530 switches from 1× to 2× mode, it first switches

to 1.5× mode for a typical duration of 1 ms before entering

2× mode.

When operating in 1.5× mode, if VOUT < VIN, then the IC

switches back to 1× mode every 130 ms, and then reenters 1.5×

mode again if necessary.

Transitions Between 1.5× and 2× Modes

The transition from 1.5× to 2× mode depends upon dropout

conditions.

When operating in 2× mode, the IC switches back to 1.5× mode

every 130 ms, and then reenters 2× mode again if necessary.

Furthermore, when in 2× mode, whenever a channel disabling

is sensed (that is, whenever ENM is held low for > 0.5 ms with

ENF high, or vice versa), the IC automatically reverts to 1.5×

mode, and then reenters 2× mode again if necessary.

Dimming

Display Backlight LED1 through LED4 Dimming The display

backlight LEDs (LED1 through LED4) brightness and on/off can

be controlled using digital input at the ENM pin. The ENM pin

accepts one-wire serial pulse input to enable the A8350 and to set

up to 11 dimming levels, from 100% down to 5%.

When ENM is initially pulled up from shutdown, after a soft-

start, the current for the backlight LEDs is programmed to 100%

of the setting current, which is determined by the current through

the ISET pin. Each subsequent pulse reduces the LED current

by 10%, and the 10th pulse reduces the current by 5%. The next

pulse restores 100% (full) brightness. Figure 6 shows the timing

diagram for ENM control.

Eff (%)

VIN

(V)

2.73.13.53.94.34.75.15.5

Rising

Falling

= 3.4 V

= 20 mA

Figure 5. Mode change transitions

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Flash/Torch LED5 and LED6 Operation The flash/torch LEDs

(LED5 and LED6) brightness and on/off can be controlled using

digital input at ENF pin. ENF accepts one-wire serial pulse input

to enable the A8530 and to set up to 11 dimming levels, from

100 mA (the default 100% level) down to 5 mA.

When the ENF pin is initially pulled up from shutdown, after a

soft-start (if the IC is not yet soft-started using the ENM pin),

the current for LED5 and LED6 is, by default, programmed to

100 mA, corresponding to 100% of flash/torch brightness. Each

subsequent pulse reduces the LED current by 10 mA, and the

10th pulse reduces the current by 5 mA. The next pulse then

restores to 100 mA (full) output current per channel. Figure 6

shows the timing diagram for ENF.

Absolute Level Operation Some applications require dimming

to a specific level, regardless of the present level of dimming.

For example, if the IC should dim to 30%, this can be done with

7 steps, as shown in figure 6, irrespective of the dimming level

in effect. This can be achieved by pulling corresponding ENx

pin low for time greater than tSHDN and then applying pulses as

shown in figure 6 (7 for 30% dimming). If the pulses are applied

within 2 to 3 ms, the display flicker is not visible. The procedure

is shown in figure 7.

Shutdown

When the ENM pin is pulled low for 0.5 ms or longer, the display

backlight channels are shut off and dimming is reset to 100%

upon the next ENM going high edge. When the ENF pin is

pulled low for 0.5 ms or longer, the brightness of the flash/torch

channels is reset to 100 mA upon the next ENF going high edge.

When both ENM and ENF are pulled low for 0.5 ms or longer,

the A8530 enters the shutdown mode.

Short Circuit Protection

The A8530 is protected against short circuits on the output. When

VOUT is externally pulled below 1.2 V, the IC enters Short Circuit

mode. The A8530 resumes normal operation when the short

circuit is removed.

Figure 7. Absolute Dimming Level Setting. With ENM pulled low longer the tSHDN,

pulsing the corresponding ENx pin sets an absolute target level.

Symbol Parameter Units/Division

C1 VENM 2.00 V

C2 VOUT 2.00 V

C3 IOUT 50 mA

t time 0.5 ms

VENM

VOUT

IOUT

Rapid pulse pattern

ENx pulled low

ISET counter resets

t > tSHDN

100%

30%

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Overvoltage Protection

The A8530 is protected up to 4.9 V supply voltage, against

accidental overvoltage caused by an open LED. When any LED

opens, VOUT will increase till 6 V. Remaining LEDs will continue

to function normally. Normal operation will be resumed when the

fault is removed.

LED Disconnection

Every LEDx pin has a disable subcircuit, as shown in figure 8.

The A8530 compares the voltage on each LED pin, and if

the voltage on the pin is greater than either VOUT – 0.4 V or

VIN – 0.4 V, then the corresponding LED pin is disabled.

If any WLED is not used, connect the corresponding pin to

VOUT. Never leave open any unused WLED pin. LED pins will

sink 20 μA typical when connected to VOUT and the correspond-

ing LED group (main or sub) is enabled.

Note: In shutdown mode (ENM = ENS = 0 V for > 0.5 ms), the

total leakage current is < 1μA.

Thermal Shutdown

The IC is internally protected against overtemperature. The

overtemperature limit is set to 165°C nominal. The IC shuts down

when the junction temperature exceeds 165°C and automatically

turns on again when the IC cools.

Component Selection

Ceramic capacitors with X5R or X7R dielectric are recom-

mended for the input capacitor, CIN, the output capacitor, COUT,

and the charge pump capacitors, C1 and C2.

Figure 8. LED disable subcircuit. Subcircuit for one LEDx pin shown. A similar block is

connected to each LEDx pin.

–

VBATT

A8530

CIN COUT

LED1

VOUT

1×, 1.5×, 2×

Charge Pump

VIN

VIN – 0.4

VOUT – 0.4 Current

Sink

LED Disable Block

One of six blocks

Ultracompact 6-Channel Backlight

and Flash/Tor ch White LED Driver

A8530

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Package ES, 3 × 3 mm 16-Pin QFN/MLP

C0.08

17X

ATerminal #1 mark area

BExposed thermal pad (reference only, terminal #1

identifier appearance at supplier discretion)

For reference only

(reference JEDEC MO-220WEED)

Dimensions in millimeters

Exact case and lead configuration at supplier discretion within limits shown

CReference land pattern layout (reference IPC7351

QFN50P300X300X80-17W4M);

All pads a minimum of 0.20 mm from all adjacent pads; adjust as

necessary to meet application process requirements and PCB layout

tolerances; when mounting on a multilayer PCB, thermal vias at the

exposed thermal pad land can improve thermal dissipation (reference

EIA/JEDEC Standard JESD51-5)

PCB Layout Reference View

B1.70

1.70

0.30

16 0.50

0.90

3.10

SEATING

PLANE

0.25 +0.05

–0.07

0.40 +0.15

–0.10

0.50 0.75 ±0.05

3.00 ±0.15

DCoplanarity includes exposed thermal pad and terminals

The products described here are manufactured under one or more U.S. patents or U.S. patents pending.

Allegro MicroSystems, Inc. reserves the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be required to per-

mit improvements in the per for mance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the

information being relied upon is current.

Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the

failure of that life support device or system, or to affect the safety or effectiveness of that device or system.

The in for ma tion in clud ed herein is believed to be ac cu rate and reliable. How ev er, Allegro MicroSystems, Inc. assumes no re spon si bil i ty for its use;

nor for any in fringe ment of patents or other rights of third parties which may result from its use.

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