TCS3772 datasheet(16/33 Pages) AMSCO

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TCS3772

COLOR LIGHT-TO-DIGITAL CONVERTER

with PROXIMITY SENSING

TAOS145B − SEPTEMBER 2012

The LUMENOLOGY

r Company

E 2012, TAOS Inc.

www.taosinc.com

Power Management

Power consumption can be managed with the Wait state, because the Wait state typically consumes only 65

μA

of IDD current. An example of the power management feature is given below. With the assumptions provided

in the example, average IDD is estimated to be 186 μA.

Table 1. Power Management

SYSTEM STATE MACHINE

STATE

PROGRAMMABLE

PARAMETER

PROGRAMMED VALUE

DURATION

TYPICAL

CURRENT

Prox Accum

PPULSE

0x04

0.056 ms

Prox Accum − LED On

0.025 ms (Note 1)

109 mA

Prox Accum − LED Off

0.031 ms (Note 2)

0.235 mA

Prox Wait

2.40 ms

0.235 mA

Prox ADC

PTIME

0xFF

2.40 ms

0.235 mA

Wait

WTIME

0xEE

43 1 ms

0 065 mA

Wait

WLONG

43.1 ms

0.065 mA

ALS Init

2.40 ms

0.235 mA

ALS ADC

ATIME

0xEE

43.1 ms

0.235 mA

NOTES: 1. Prox Accum − LED On time = 6.3

μs per pulse

× 4 pulses = 25.2μs = 0.025 ms

2. Prox Accum − LED Off time = 7.7

μs per pulse

× 4 pulses = 30.9μs = 0.031 ms

Average IDD Current = ((0.025

× 109) + (0.031 × 0.235) + (2.40 × 0.235) +

(43.1

× 0.065) + (43.1 × 0.263) + (2.40 × 0.235 × 2)) / 93 186 μA

Keeping with the same programmed values as the example, Table 2 shows how the average IDD current is

affected by the Wait state time, which is determined by WEN, WTIME, and WLONG. Note that the worst-case

current occurs when the Wait state is not enabled.

Table 2. Average IDD Current

WEN

WTIME

WLONG

WAIT STATE

AVERAGE IDD CURRENT

n/a

0 ms

289

μA

0xFF

2.40 ms

279

μA

0xEE

43.1 ms

186

μA

0x00

613 ms

μA

0x00

7.36 s

μA

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