I

I

V

Symbol

Parameter

Limits

Units

Min

Max

1

Hold Time (repeated) START Condition

0.6

µs

2

Clock Low Time

1.3

µs

3

Clock High Time

600

ns

4

Setup Time for a Repeated START Condition

600

ns

5

Data Hold Time

300

900

ns

6

Data Setup Time

100

ns

7

Rise Time of SDA and SCL

20 + 0.1C

b

300

ns

8

Fall Time of SDA and SCL

15 + 0.1C

b

300

ns

9

Set-Up Time for STOP Condition

600

ns

10

Bus Free Time between a STOP and a START Condition

1.3

µs

C

b

Capacitive Load for Each Bus Line

10

200

pF

Note: Data guaranteed by design.

A/D Converter for Ambient Light Measurement

Electrical Characteristics

Symbol

Parameter

Conditions

Min

Typ

Max

Units

V

IN RANGE

Input Voltage

AD Output: 00h

1.23

V

AD Output: FFh

2.46

V

DNL

Differential Non-Linearity

–1.5

+1.5

LSB

GE

Gain Error

−5

+5

LSB

PSS

Power Supply Sensitivity

3.1V

≤ V

DD

≤ 4.2V

LSB

f(conv)

Conversion Rate

Without Averaging

217

Hz

With Averaging

(64 samples)

3.4

Hz

t

STARTUP

Startup Time

100

ms

I

AIN

Input Current

µA

I

AREF

Maximum Output Current

AREF Output Current Sink

200

µA

R

AREF

AREF Output Resistance

110

Ω

ADC output AIN[7:0] can be read from address 0CH after startup time. Overflow bit can be read from bit D7 in address 0BH. The

overflow bit indicates that input voltage exceeds the input voltage range of the ADC. The ADC output value in this case is FFH.

When averaging is on, the overflow is high, if any of the 64 conversion results in the averaging period overflows. Thus the

averaged result may be considerably below maximum and the overflow can still be high, if the input signal is noisy.

Examples for optical sensor are photodiode SHF2400 and phototransistor SFH3410 from Osram or BSC 3216 G1 optical sensor

from TDK.

ADC can be used for temperature measurement with a thermistor. It enables temperature compensated LED driving.

If ADC is not used, it should be disabled by writing en_ambadc bit low. AIN and AREF pins can be left unconnected

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