PCM186X datasheet(39/115 Pages) TI1

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REF_LEVEL

(1) DIFF_LEVEL > 0

Time

An interrupt is generated

(2) DIFF_LEVEL < 0

PCM1860, PCM1862, PCM1864, PCM1864-Q1

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SLASE55A – NOVEMBER 2014 – REVISED DECEMBER 2014

ADCs (continued)

An example of the code required is shown in Table 16.

10.13.3 Secondary ADC DC Level Change Detection

This function is used for external analog controls, such as potentiometers to set volume, tone control, or a

sensor.

There are two parameters for the DC level change detection. Reference level (REF_LEVEL) and Difference level

(DIFF_LEVEL). Each input pin (input 1 through 8) has a different reference and difference level.

Users set a reference point, and a difference point. If the voltage at the control point crosses the difference point

then an interrupt is driven from the device. This is useful for filtering out noise, as well as reducing the load on

the host processor for controls that tend to be "set and forget" (such as volume).

The data from the secondary ADC can also be streamed out of the device in TDM form and directly from the I2C

detector.

Figure 32. DC Detection function

10.14 Energysense

Energysense functionality has been added to the PCM186x to aid with auto-sleep and auto-wakeup for audio

systems that are expected to be sold within the European Union. The latest EcoDesign legislation in Europe has

demanded that products consume less than 500 mW in standby. Most off-the-shelf external power adaptors can

consume 300mW when idling, leaving the system with only 200 mW available. In many systems that requires

that almost everything be powered down in sleep mode, to be powered back up when signal enterers the system

again.

Energysense is split into two functions: Signal Loss Flag and Signal Resume Flag. Both are available on the

PCM186x software controlled devices. The PCM1860 only supports signal resume. Usage is shown below. By

default, the Signal Resume Threshold is set at –57 dBFS.

Table 15. Energysense States

MODE

PURPOSE

CONDITIONS

POSITIVE OUTCOME

WORST CASE

SLEEP

Detect Input Signal and Wake up

BCK and LRCK stopped (not locked) or

Host Wakes and services interrupt (reads

Host Doesn't respond or start clocks.

(Signal Detect

from SLEEP

Mode)

Trigger Interrupt when input crosses

Host Starts BCK/LRCK. (Moving system to

PCM186x keeps triggering interrupts until

above (threshold)

ACTIVE mode) or writes to register.

host responds.

Trigger for 1ms every X seconds until

clocks start (x=1 by default)

ACTIVE

Detect content below (threshold)

BCK and LRCK are currently running

System can choose to go to sleep or not. If

If system does not sleep, remain in Mode

(Signal Loss

over time

not, reset interrupt

2, and prompt every Y.

Mode)

Assist system to sleep after

If no content above -(threshold) dB for Y

If System decides to sleep, stop BCK/LRCK.

MCU will need to mask that interrupt.

audio inactivity (for example,

minutes, drive interrupt.

This will move PCM186x to SLEEP mode.

Source is off, but speaker still

on)

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Product Folder Links: PCM1860 PCM1862 PCM1864 PCM1864-Q1

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