IS31BL3212 Datasheet by ISSI, Integrated Silicon Solution Inc

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IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 1

Rev. C, 06/24/2014

FOUR CHANNEL CONSTANT CURRENT LED DRIVER

June 2014

GENERAL DESCRIPTION

The IS31BL3212 provides four regulated current

sources, delivers up to 23mA of load current to

accommodate four white LEDs. It requires no charge

pump, has no noise and significantly improved the

efficiency.

The serial digital input is used to enable, disable, and

set current for each LED with 16 settings down to

0.69mA. A low-current shutdown feature disconnects

the load from the input and reduces quiescent current

typically 1.0mA.

The IS31BL3212 is available in a Pb-free,

space-saving 2mm×2mm DFN-8 and SOT23-6

package.

FEATURES

 Ultra low headroom voltage

 Cost effective LED driver

 Four channel constant current output ideal for

driving LEDs

 Best noise and efficiency performance

 Ultra low quiescent supply current: 1.0mA (Typ.)

 Highly integrated design, minimal component

 Low shutdown current: 1.0μA (Typ.)

APPLICATIONS

 White LED display backlights

 White LED keypad backlights

 Cell Li-ion battery-operated equipment including

PDAs, hand-held PCs, cellular phone

TYPICAL APPLICATION CIRCUIT

Figure 1 Typical Application Circuit

Figure 2 Application Circuit for Less Than 4 LEDs

Note: If less than four LEDs connected, the left pin can be floating or connected to GND. Connecting to GND is recommended.

EN/SET

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 2

Rev. C, 06/24/2014

PIN CONFIGURATION

Package Pin Configuration (Top View)

DFN-8

SOT23-6

VCC

GND

EN/SET

PIN DESCRIPTION

No. Pin Description

DFN-8 SOT23-6

1 - D4 White LED channel.

2~4 6~4 D3~D1 White LED channel.

5 3 VCC Power supply input.

6 2 GND Ground.

7 1 EN/SET Serial digital input, control the output

current. Internal 500kΩ pull down resistor.

8 - NC No connection.

Thermal Pad Connect to GND.

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 3

Rev. C, 06/24/2014

ORDERING INFORMATION

Industrial Range: -40°C to +85°C

Order Part No. Package QTY/Reel

IS31BL3212-DLS2-TR

IS31BL3212-STLS2-TR

DFN-8, Lead-free

SOT23-6, Lead-free 3000

Copyright©2014IntegratedSiliconSolution,Inc.Allrightsreserved.ISSIreservestherighttomakechangestothisspecificationanditsproductsatany

timewithoutnotice.ISSIassumesnoliabilityarisingoutoftheapplicationoruseofanyinformation,productsorservicesdescribedherein.Customersare

advisedtoobtainthelatestversionofthisdevicespecificationbeforerelyingonanypublishedinformationandbeforeplacingordersforproducts.

IntegratedSiliconSolution,Inc.doesnotrecommendtheuseofanyofitsproductsinlifesupportapplicationswherethefailureormalfunctionofthe

productcanreasonablybeexpectedtocausefailureofthelifesupportsystemortosignificantlyaffectitssafetyoreffectiveness.Productsarenot

authorizedforuseinsuchapplicationsunlessIntegratedSiliconSolution,Inc.receiveswrittenassurancetoitssatisfaction,that:

a.)theriskofinjuryordamagehasbeenminimized;

b.)theuserassumeallsuchrisks;and

c.)potentialliabilityofIntegratedSiliconSolution,Incisadequatelyprotectedunderthecircumstances

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 4

Rev. C, 06/24/2014

ABSOLUTE MAXIMUM RATINGS

Supply voltage, VCC -0.3V ~ +6.0V

EN/SET voltage to GND, VEN/SET -0.3V ~ VCC+0.3V

Maximum junction temperature, TJMAX 150°C

Storage temperature range, TSTG -65°C ~ +150°C

Operating temperature range, TA −40°C ~ +85°C

ESD (HBM)

ESD (CDM)

3kV

1kV

Note:

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and

functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not

implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

TA = 25°C, unless otherwise noted. Typical values are TA = 25°C, VCC = 3.6V. (Note 1)

Symbol Parameter Condition Min. Typ. Max. Unit

Input Power Supply

VCC Operation range 2.7 5.5 V

IIN Operating current 3.0 ≤ VCC ≤ 5.5, active no load,

current data = 1 (Note 2) 1.0 mA

ISHDN Shutdown current VEN/SET = 0V 1.0 2.6 μA

VHR Minimum headroom voltage (DX) IDX = 15mA, VCC = 3.3V 49 mV

VHR Minimum headroom voltage (DX) IDX= 20mA, VCC = 3.3V 60 mV

IDX Output current regulation Data = 1 (Note 2) 23 mA

EN/SET

VEN/SET(L) Enable threshold low VCC = 2.7V 0.4 V

VEN/SET(H) Enable threshold high VCC = 5.5V 1.4 V

tEN/SET LO EN/SET low time 0.3 75 μs

tEN/SET_HI_MIN Minimum EN/SET high time (Note 3) 1.0 μs

tEN/SET_HI_MAX Maximum EN/SET high time (Note 3) 92 μs

tOFF EN/SET off timeout 500 μs

tLAT EN/SET latch timeout 500 μs

REN/SET DOWN EN/SET pull down resistor (Note 3) 500 kΩ

Note 1: The IS31BL3212 is production tested at room temperature but guaranteed to meet performance specifications over other temperature

range by design, characterization, and correlation with statistical process controls.

Note 2: See PCC wire Serial Interface section in application information for more.

Note 3: Guaranteed by design.

Integrate Rev. C,

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 5

Rev. C, 06/24/2014

FUNCTIONAL BLOCK DIAGRAM

BG Output D1~D4

Data

VCC

GND

IBias

EN/SET

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 6

Rev. C, 06/24/2014

APPLICATION INFORMATION

OUTPUT CURRENT CAPABILITY

In order for the output currents to be regulated properly,

sufficient headroom voltage (VHR) is required. The

headroom voltage refers to the minimum amount of

voltage that must be present across the current source

in order to ensure the desired current is realizable. To

ensure the desired current is obtained, apply the

following equations to find the minimum input voltage

required:

VCC - VLEDX ≥ VHR

Notice that if less than four LEDs connected, the left

pin can be floating or connected to GND.

FUNCTIONAL DESCRIPTION

The four constant current source outputs (D1 to D4)

can drive four individual LEDs with a maximum current

of 23mA each. The PCC wire serial interface enables

the IS31BL3212 and sets the current source

magnitudes.

CONSTANT CURRENT OUTPUT LEVEL SETTINGS

The constant current source levels for D1 to D4 are set

via the serial interface according to a logarithmic scale.

For the whole 16 codes, each code is approximately

1.5dB lower than the previous code. In this manner,

LED brightness appears linear with each increasing

code count. Because the outputs D1 to D4 are true

independent constant current sources, the voltage

observed on any single given output will be determined

by the actual forward voltage (VF) for the LED being

driven.

Since the output current sources of the IS31BL3212

are programmable, no PWM (pulse width modulation)

or additional control circuitry is needed to control LED

brightness. This feature greatly reduces the burden on

a microcontroller or system IC to manage LED or

display brightness, allowing the user to "set it and

forget it." With its high-speed serial interface (1MHz

data rate), the output current of the IS31BL3212 can

be changed successively to brighten or dim LEDs, in

smooth transitions (e.g., to fade-out) or in abrupt steps,

giving the user complete programmability and

real-time control of LED brightness.

PCC WIRE SERIAL INTERFACE

The current level magnitude is controlled by Pulse

Count Control (PCC wire) serial interface. The

interface records rising edges of the EN/SET pin and

decodes them into 16 different states. The 16 current

level settings available are indicated in Table 1.

Table 1: Current Level Setting

Data Output(mA/Ch) Data Output(mA/Ch)

1 23.0 9 5.8

2 19.6 10 4.8

3 16.1 11 4.1

4 13.8 12 3.5

5 11.8 13 2.8

6 9.9 14 2.1

7 8.1 15 1.4

8 6.9 16 0.7

The PCC wire serial interface has flexible timing.

After data is submitted, EN/SET is held high to latch

the data. Once EN/SET has been held in the logic high

state for time TLAT, the programmed current becomes

active and the internal data register is reset to zero.

For subsequent current level programming, the

number of rising edges corresponding to the desired

code must be entered on the EN/SET pin.

PCC WIRE SERIAL INTERFACE TIMING

When EN/SET is held low for an amount of time

greater than TOFF, the IS31BL3212 enters into

shutdown mode and draws 1.0µA typically from VCC.

The internal data register is reset to zero during

shutdown.

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IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 7

Rev. C, 06/24/2014

LED SELECTION

The IS31BL3212 has low headroom voltage and it is

designed to drive white-LEDs.

The drive current will automatically scale down to

reduce the LED current consumption.

INPUT CAPACITOR SELECTION

The IS31BL3212 is designed to run off of a fixed input

voltage. Depending on the stability and condition of

this voltage rail, it may be necessary to add a small

input capacitor to help filter out any noise that may be

present on the line. In the event that filtering is needed,

ceramic composition capacitors are highly recom-

mended over all other types of capacitors for use with

the IS31BL3212. Ceramic capacitors offer many

advantages over their tantalum and aluminum

electrolytic counterparts. A ceramic capacitor typically

has very low ESR, is lowest cost, has a smaller PCB

footprint, and is non-polarized. Low ESR ceramic

capacitors help to maximize charge pump transient

response. Since ceramic capacitors are non-polarized,

they are not prone to incorrect connection damage.

THERMAL PROTECTION

The IS31BL3212 has a thermal protection circuit that

will shut down the chip if the die temperature rises

above the thermal limit.

Although the IS31BL3212 is designed for driving white

LEDs, the device also can be used to drive most types

of LEDs with forward voltage specifications ranging

from 2.0V to 4.7V. LED applications may include main

and sub-LCD display backlighting, camera photo-flash

applications, color (RGB) LEDs, infrared (IR) diodes

for remotes, and other loads benefiting from a

controlled output current generated from a varying

input voltage. Since the D1 to D4 output current

sources are matched with negligible voltage

dependence, the LED brightness will be matched

regardless of the specific LED forward voltage (VF)

levels. In some instances (e.g., in high luminous output

applications such as photo flash), it may be necessary

to drive high-VF type LEDs. The low dropout current

sources in the IS31BL3212 make it capable of driving

LEDs with forward voltages as high as 4.7V at full

current from an input supply of 2.7V to 5.0V. Outputs

can be paralleled to drive high-current LEDs without

complication

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IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 8

Rev. C, 06/24/2014

CLASSIFICATION REFLOW PROFILES

Profile Feature Pb-Free Assembly

Preheat & Soak

Temperature min (Tsmin)

Temperature max (Tsmax)

Time (Tsmin to Tsmax) (ts)

150°C

200°C

60-120 seconds

Average ramp-up rate (Tsmax to Tp) 3°C/second max.

Liquidous temperature (TL)

Time at liquidous (tL)

217°C

60-150 seconds

Peak package body temperature (Tp)* Max 260°C

Time (tp)** within 5°C of the specified

classification temperature (Tc) Max 30 seconds

Average ramp-down rate (Tp to Tsmax) 6°C/second max.

Time 25°C to peak temperature 8 minutes max.

Figure 3 Classification Profile

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IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 9

Rev. C, 06/24/2014

PACKAGE INFORMATION

DFN-8

H Dimensions In Millimeters Dimensions In Inches SVMbOI Min Max Min Max A 1.050 1.250 0.041 0.049 A1 0000 0 100 0 000 0 004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 9 0950 E80) 0.037(BSC) e1 1800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 9 0" 8" 0" B“

IS31BL3212

Integrated Silicon Solution, Inc. – www.issi.com 10

Rev. C, 06/24/2014

SOT23-6

Note: All dimensions in millimeters unless otherwise stated.

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