NOA1302DCRG - ON Semiconductor

August, 2009 − Rev. 1

1Publication Order Number:

NOA1302/D

NOA1302

Ambient Light Sensor with

I2C Interface

Description

The NOA1302 integrates a wide dynamic range ambient light

sensor (ALS) with a 16−bit ADC and a 2−wire I2C digital interface.

The NOA1302 ambient light sensor provides a linear response over

the range of close to 0 lux to well over 100,000 lux with programmable

integration times to optimize noise performance. The sensor employs

proprietary CMOS image sensing technology from ON Semiconductor

which provides low noise and high dynamic range output signals and

light response similar to the response of the human eye.

The NOA1302 operates as an I2C slave device and supports

commands to set options in the device and read out the ambient light

intensity count.

Features

•Senses Ambient Light and Provides an Output Count Proportional to

the Ambient Light Intensity

•Human Eye Type of Spectral Response

•Provides Comfortable Levels of Display Depending on the Viewing

Environment

•Linear Response Over the Full Operating Range

•Senses Intensity of Ambient Light from ~0 Lux to over 100,000 Lux

•Programmable Integration Times of 400 ms, 200 ms and 100 ms

•No External Components Required

•Low Power Consumption

•Built−in 16−bit ADC

•I2C Serial Communication Port − Standard Mode – 100 kHz

− Fast Mode – 400 kHz

•This Device is Pb−Free, Halogen Free/BFR Free, and RoHS

Compliant

Applications

•Saves Display Power in Applications such as:

− Laptops, Notebooks, Digital Signage

− LCD TVs and Monitors, Digital Picture Frames

− LED Indoor/Outdoor Residential and Street Lights

SDA

SCL

VDD

VSS

1k R2

Vin = 3.3 V

C1 C2

IC1

NOA1302

MCU

SDA

SCL

hvhv

Figure 1. Typical Application Circuit

10m0.1m

CL not to exceed 250 pF

including all parasitic

capacitances

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1302= Specific Device Code

A = Assembly Location

Y = Year

W = Work Week

G= Pb−Free Package

1302

ÉÉ

CTSSOP−8

DC SUFFIX

CASE 949AA

ÉÉ

PIN ASSIGNMENT

VDD

SDA

VSS

SCL

(Top View)

See detailed ordering and shipping information in the package

dimensions section on page 2 of this data sheet.

ORDERING INFORMATION

MARKING DIAGRAM

AYWG

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Table 1. ORDERING INFORMATION

Part Number Package Shipping Configuration†Temperature Range

NOA1302DCRG CTSSOP−8

(Pb−Free)

2500 / Tape & Reel 0°C to 70°C

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specification Brochure, BRD8011/D.

SDA

SCL

hn16−bits

ADC

Figure 2. Simplified Block Diagram

I2C Serial

Interface

Control

Table 2. PIN FUNCTION DESCRIPTION

Pin Pin Name Description

1, 2, 7, 8 N/C Not connected, leave this pin unconnected.

3 VSS Ground pin.

4 SCL External I2C clock supplied by the I2C master.

5 SDA Bi−directional data signal for communications between this device and the I2C master.

6 VDD Power pin.

Table 3. ABSOLUTE MAXIMUM RATINGS

Rating Symbol Value Unit

Input power supply VDD 5.5 V

Input voltage range Vin −0.3 to VDD + 0.2 V

Output voltage range Vout −0.3 to VDD + 0.2 V

Maximum Junction Temperature TJ(max) 85 °C

Storage Temperature TSTG −40 to 85 °C

ESD Capability, Human Body Model (Note 1)

ESD Capability, Charged Device Model (Note 1)

ESD Capability, Machine Model (Note 1)

ESDHBM

ESDCDM

ESDMM

2.5

750

250

Moisture Sensitivity Level MSL 3 −

Lead Temperature Soldering (Note 2) TSLD 260 °C

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

1. This device incorporates ESD protection and is tested by the following methods:

ESD Human Body Model tested per EIA/JESD22−A114

ESD Charged Device Model tested per ESD−STM5.3.1−1999

ESD Machine Model tested per EIA/JESD22−A115

Latchup Current Maximum Rating: ≤ 100 mA per JEDEC standard: JESD78

2. For information, please refer to our Soldering and Mounting Techniques Reference Manual, SOLDERRM/D

NOA1302

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Table 4. OPERATING RANGES

Rating Symbol

Standard Mode Fast Mode

Unit

Min Max Min Max

Power supply voltage VDD 3.0 3.6 3.0 3.6 V

Power supply current (VDD = 3.3 V) IDD 325 950 325 950 mA

Low level input voltage (VDD related input levels) VIL −0.3 0.3 VDD −0.3 0.3 VDD V

High level input voltage (VDD related input levels) VIH 0.7 VDD VDD + 0.2 0.7 VDD VDD + 0.2 V

Hysteresis of Schmitt trigger inputs (VDD > 2 V) Vhys N/A N/A 0.05 VDD −V

Low level output voltage (open drain) at 3 mA sink

current (VDD > 2 V)

VOL 0 0.4 0 0.4 V

High level output voltage (with 1 kW pullup resist-

ance) at and output current of −20 mA (VDD > 2 V)

VOH VDD − 0.1 N/A VDD − 0.1 N/A V

Input current of IO pin with an input voltage

between 0.1 VDD and 0.9 VDD

II−10 10 −10 10 mA

Output low current IOL −45 −45 mA

Capacitance on IO pin CI−10 −10 pF

Operating free−air temperature range TA0 70 0 70 °C

Table 5. ELECTRICAL CHARACTERISTICS

(Unless otherwise specified, these specifications apply over VDD = 3.3 V, 0°C < TA < 70°C) (Note 3)

Parameter Symbol

Standard Mode Fast Mode

Unit

Min Max Min Max

SCL clock frequency fSCL 10 100 100 400 kHz

Hold time for START condition. After this period, the first clock

pulse is generated.

tHD;STA 4.0 −0.6 −mS

Low period of SCL clock tLOW 4.7 1.3 mS

High period of SCL clock tHIGH 4.0 0.6 mS

Data hold time for I2C−bus devices tHD;DAT_d 0 3.45 0 0.9 mS

Data set−up time tSU;DAT 250 −100 −nS

Rise time of both SDA and SCL (input signals) (Note 4) tr_INPUT 5 300 5 300 nS

Fall time of both SDA and SCL (input signals) (Note 4) tf_INPUT 5 300 5 300 nS

Rise time of SDA output signal (Note 4) tr_OUT −1000 −1000 nS

Fall time of SDA output signal (Note 4) tf_OUT −1000 −1000 nS

Output fall time from VIHmin to VILmax with a bus capacitance

from 10 pF to 250 pF. (Note 5)

tof 2 250 2 250 nS

Set−up time for STOP condition tSU;STO 4.0 −0.6 −mS

Bus free time between STOP and START condition tBUF 4.7 −1.3 −mS

Capacitive load for each bus line

(including all parasitic capacitance)

CL−250 −250 pF

Noise margin at the low level for each connected device

(including hysteresis)

VnL 0.1 VDD −0.1 VDD −V

Noise margin at the high level for each connected device

(including hysteresis)

VnH 0.2 VDD −0.2 VDD −V

3. Refer to Figure 3 for more information on AC characteristics

4. The rise time and fall time are measured with a pull−up resistor Rp = 1 kW and Cb of 250 pF (including all parasitic capacitances).

5. Cb = capacitance of one bus line, maximum value of which including all parasitic capacitances should be less than 250 pF.

NOA1302

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Table 6. OPTICAL CHARACTERISTICS (Unless otherwise specified, these specifications are for VDD = 3.3 V, TA = 25°C)

Parameter Test Conditions Symbol Min Typ Max Unit

Irradiance responsivity lp (see Figure 5) Re545 nM

Illuminance responsivity Incandescent light source:

Ev = 100 lux (see Figure 6)

Rv150 Counts

Incandescent light source:

Ev = 1000 lux (see Figure 6)

1480

Illuminance responsivity Fluorescent light source:

Ev = 100 lux (see Figure 7)

Rv130 Counts

Fluorescent light source:

Ev = 1000 lux (see Figure 7)

1290

Dark current Ev = 0 lux (see Figure 9) 2 Counts

Figure 3. AC Characteristics

SDA

SCL

tLOW tr

tHD;STA

tHD;DAT tHIGH

tSU;DAT tf

tSU;STO SP

trtBUF

tSP

NOA1302

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TYPICAL CHARACTERISTICS

Figure 4. Photo Diode Spectral Response (Without Filter) Figure 5. Human Eye vs. NOA1302 Spectral

Response

Figure 6. Incandescent Light Response

(200 ms Integration)

Figure 7. Fluorescent Light Response

(200 ms Integration)

Figure 8. Light Response vs. VDD Figure 9. Dark Counts vs. Temperature

(200 ms Integration)

NOA1302

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TYPICAL CHARACTERISTICS

Figure 10. Dark Counts vs. Vdd Figure 11. Idd vs. Temperature

Figure 12. Idd vs.Vdd Figure 13. Idd vs Ev

Figure 14. Maximum Value of RP (in kW)

as a function of Bus Capacitance (in pF)

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DESCRIPTION OF OPERATION

Ambient Light Sensor Architecture

The NOA1302 employs a sensitive photo diode fabricated

in ON Semiconductor’s standard CMOS process

technology. The major components of this sensor are as

shown in Figure 2. The photons which are to be detected pass

through an ON Semiconductor proprietary color filter

limiting extraneous photons and thus performing as a band

pass filter on the incident wave front. The filter only

transmits photons in the visible spectrum which are

primarily detected by the human eye. The photo response of

this sensor is as shown in Figure 5.

The ambient light signal detected by the photo diode is

converted to digital signal using a variable slope integrating

ADC with a resolution of 16−bits, unsigned. The ADC value

is provided to the control block connected to the I2C

interface block.

Equation 1 shows the relationship of output counts Cnt as

a function of integration constant Ik, integration time Tint (in

seconds) and the intensity of the ambient light, IL(in lux), at

room temperature (25°C).

IL+

Cnt

(Ik@Tint)(eq. 1)

Where:

Ik = 6.67 (for fluorescent light)

Ik = 7.5 (for incandescent light)

Hence the intensity of the ambient fluorescent light (in lux):

IL+

Cnt

(6.67 @Tint)(eq. 2)

and the intensity of the ambient incandescent light (in lux):

IL+

Cnt

(7.5 @Tint)(eq. 3)

For example let:

Cnt = 1200

Tint = 200 mS

Intensity of ambient incandescent light, IL(in lux):

IL+1200

(7.5 @200 mS) (eq. 4)

IL = 800 lux

I2C Interface

The NOA1302 operates on the I2C bus as a slave device.

The I2C address is fixed at 0x39 (hexadecimal 39). Registers

can be programmed by sending commands over an I2C bus.

Ambient light intensity count value can be obtained by

reading registers. The ambient light intensity count is 16

bits, hence two I2C read operations are needed. This device

supports both standard (100 Kbit/s) and fast mode

(400 Kbit/s) of operation on the I2C bus.

Figure 15 shows an I2C write operation. To write to an

internal register of the NOA1302 a write command must be

sent by an I2C master. The write command begins with a start

condition. After the start condition, seven bits of address are

sent MSB first. RD/WR_ command bit follows the address

bits. Upon receiving a valid address the device responds by

driving SDA low for an ACK. After receiving an ACK, the

I2C master sends eight bits of data with MSB first. Upon

receiving eight bits of data the NOA1302 generates an ACK.

The I2C master terminates this write command with a stop

condition.

Figure 15. I2C Write Command

SDA

SCL

Start

Condition Stop

Condition

A[6:0] WR ACK ACK

D[7:0]

Figure 16 shows an I2C read command sent by the master

to the slave device. The I2C read command begins with a

start condition. After the start condition, seven bits of

address are sent by the master MSB first, followed by the

RD/WR_ command bit. For a read command the RD/WR_

bit is high. Upon receiving the address bits and RD/WR_

command bits the device responds with an ACK. After

sending an ACK, the device sends eight bits of data MSB

first. After receiving the data, the master terminates this

transaction by issuing a NACK command to indicate that the

master only wanted to read one byte from the device. The

master generates a stop condition to end this transaction.

Repeated START condition is not supported. Each I2C

transaction must be terminated with a STOP condition after

all required bits have been transmitted and received.

Figure 16. I2C Read Command

SDA

SCL

Start

Condition Stop

Condition

A[6:0] RD ACK NACK

D[7:0]

Programmer’s Model

Ambient light intensity count is obtained from the the

NOA1302 by issuing a fixed sequence of I2C commands.

Integration time is programmable by writing different

values to the integration time register. The following

sections describe what a programmer needs to know about

issuing commands to the chip and register access.

Integration Time Register

Table 7 describes integration time register which controls

the exposure time. This register has three bits, EC[2:0]

which control the duration of the integration time.

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Table 7. INTEGRATION TIME REGISTER

EC[2,1,0] Operation Integration Time

000 Normal mode of operation 400 ms

001 Normal mode of operation 200 ms (Default)

010 Normal mode of operation 100 ms

011 Test mode 16.7 ms

100 Simulation test mode use

only

1.0 ms

101 Reserved for future use

110 Reserved for future use

111 Reserved for future use

Programming Sequence and Command Summary

This section describes supported commands and

programming sequence. The NOA1302 only supports single

byte write and a single byte read I2C commands. Ambient

light intensity count is 16 bits wide, thus two I2C read

commands are needed.

Table 8 describes supported commands. All of these

commands have to be sent to the fixed address (0x39).

Table 8. DEVICE COMMANDS

Command Function

0x00h Start reading ADC data

0x03h Complete reading ADC data

0x1Dh Change EC[0] to 0

0x18h Reset EC[2:0] to default value (001)

0x43h Prepare ADC LS byte for reading

0x83h Prepare ADC MS byte for reading

0x88h Change EC[1] to 1

0x90h Change EC[2] to 1

Programming Sequence

To read 16 bits wide ambient light intensity count, the

following commands must be issued in sequence:

1. Send write command 0x00h to start the ADC

conversion cycle.

2. Send write command 0x03h to complete the ADC

cycle.

3. Send write command 0x43h to prepare the LS byte

for reading.

4. Send read byte command, returns LS byte of

count.

5. Send write command 0x83h to prepare the MS

byte for reading.

6. Send read byte command, returns MS byte of

count.

To change the integration time, for example to 100 ms, the

following commands must be used in sequence:

1. Send write command 0x1Dh to set EC[0] = 0.

2. Send write command 0x88h to set EC[1] = 1, now

EC[2:0] = 010.

Rise and Fall Time of SDA (Output)

Proper operation of the I2C bus depends on keeping the

bus capacitance low and selecting suitable pull−up resistor

values. Figure 17 and Figure 18 show the rise and fall time

on SDA in output mode under maximum load conditions.

The measurement set−up is shown in Figure 19. Figure 14

shows the maximum value of the pull−up resistor (RP) as a

function of the I2C data bus capacitance.

RP = 1 kW

CL = 250 pF (including all parasitic caps)

tr = 530 ns

Figure 17. SDA Rise Time (tr)

RP = 1 kW

CL = 250 pF (including all parasitic caps)

tf = 21 ns

Figure 18. SDA Fall Time (tf)

hn16−bits

NOA1302

LED

Pulse

Generator

SDA

SCL

ADC

Control

Figure 19. Measurement Set−up

I2C Serial

Interface

NOA1302

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PACKAGE DIMENSIONS

CTSSOP8 3x3

CASE 949AA−01

ISSUE O

A-B

0.15 DC

NOTES:

1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994.

2. CONTROLLING DIMENSION: MILLIMETER.

3. DIMENSION b DOES NOT INCLUDE DAMBAR PROTRUSION AND IS

DETERMINED BETWEEN 0.08 AND 0.15 MM FROM THE LEAD TIP.

4. DIMENSIONS D AND E1 DOES NOT INCLUDE MOLD

PROTRUSIONS, TIE BAR BURRS, GATE BURRS OR FLASH. END

FLASH SHALL NOT EXCEED 0.25 PER SIDE. DIMENSIONS D AND

E1 DO INCLUDE ANY MOLD CAVITY MISMATCH AND ARE

DETERMINED AT THE GAUGE PLANE.

5. DATUMS A AND B TO BE DETERMINED AT THE GAUGE PLANE.

6. DETAILS OF THE PIN 1 IDENTIFIER ARE OPTIONAL, BUT MUST BE

LOCATED WITHIN THIS ZONE.

PIN 1

0.20

SEATING

PLANE

A1 c

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

SOLDERING FOOTPRINT*

DIM

MIN MAX

MILLIMETERS

−−− 1.10

A1 0.00 0.14

A2 0.73 0.93

b0.24 0.39

c0.13 0.24

D2 0.66 1.37

D3.00 BSC

E2 0.41 1.37

0.39 0.67

E1 3.00 BSC

e0.65 BSC

E4.90 BSC

M°°

DIMENSIONS: MILLIMETERS

1.05

0.48 8X

0.72

0.65

PITCH

INDICATOR

NOTE 5

NOTE 6

NOTE 3

TOP VIEW

NOTE 5

e/2

AUXILIARY

TOP VIEW

END VIEW

SIDE VIEW

A2 C

0.15 C

DETAIL A

GAUGE

PLANE

0.25

DETAIL A

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Phone: 81−3−5773−3850

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