WM8960 データシートの表示（PDF） - Cirrus Logic

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WM8960

Stereo CODEC with 1W Stereo Class D Speaker Drivers and Headphone Drivers for Portable Audio Applications

Cirrus Logic 

WM8960

INTERNAL POWER ON RESET CIRCUIT

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Figure 5 Internal Power on Reset Circuit Schematic

The WM8960 includes an internal Power-On-Reset Circuit, as shown in Figure 5, which is used to

reset the digital logic into a default state after power up. The POR circuit is powered from AVDD and

monitors DCVDD. It asserts PORB low if AVDD or DCVDD is below a minimum threshold.

Figure 6 Typical Power up Sequence where AVDD is Powered before DCVDD

Figure 6 shows a typical power-up sequence where AVDD comes up first. When AVDD goes above

the minimum threshold, Vpora, there is enough voltage for the circuit to guarantee PORB is asserted

low and the chip is held in reset. In this condition, all writes to the control interface are ignored. Now

AVDD is at full supply level. Next DCVDD rises to Vpord_on and PORB is released high and all registers

are in their default state and writes to the control interface may take place.

On power down, where AVDD falls first, PORB is asserted low whenever AVDD drops below the

minimum threshold Vpora_off.

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PD, August 2013, Rev 4.2

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