XE3005 ETC, XE3005 Datasheet - Page 10

• Manufacturer Part Number: XE3005
• Description: (XE3005 / XE3006) Low-Power Audio CODEC
• Manufacturer: ETC

2.1.10 Start-up and Initialization
The CODEC generates its own power on reset signal after a power supply is connected to the VDD pin. The
reset signal is made available for the user at the pin NRESET. The rising edge of the NRESET indicates that the
startup sequence of the CODEC has finished. In most applications the NRESET pin can be left open.
The NRESET signal generated by the CODEC is used to initialize the various blocks in the device and
guarantees a correct start-up of the circuit. The start-up sequence that is automatically carried out upon power-up
of the device is listed below and illustrated in Figure 10.
1) NRESET is low (0V) when the device is not powered and remains low for a short time when VDD (upper
2) As soon as the MCLK signal is present, a counter is activated that counts 2
The user can use the NRESET pin in 3 different ways and combinations:
10
curve in Figure 10) is applied. The low state sustains while VDD, VREG16, VREF are stabilizing.
moment the NRESET is in the high state (VDD).
1) Leave the NRESET pin not connected. In this case the CODEC will startup as described in figure 10.
2) Use the NRESET pin as an output to indicate, to e.g. a microcontroller, that the CODEC finished its
3) Use the NRESET pin to force a re-initialisation of the registers to their default values. In this case the
power up sequence and that the CODEC is ready to operate.
user has to force the NRESET to 0V for at least 32 periods of the MCLK. The circuit which forces the
NRESET to 0V should be able to sink at least 50 uA.
NRESET
MCLK
Figure 10: Startup sequence and NRESET signal after power-on.
977 ms (MCLK=2.048KHz)
main reset
. . .
VDD = 1.8..3.3V
VREG16 = 1.6V
VREF = 1.2V
21
periods of the MCLK. After this
Data Sheet
XE3005/XE3006
time
D0212-116