PCF26100 datasheet(11/28 Pages) PHILIPS

11 / 28 page

2001 Jun 19

Philips Semiconductors

Preliminary speciﬁcation

Bluetooth Adapter IC

PCF26100

6.3.2

RESET

The PCF26100 is reset with a Power-on reset using the

VIO_POWER signal. This will reset all registers and put

the device into a known state. The POR_EXT reset signal

will also reset the device and put it in the same state as the

Power-on reset. However, POR_EXT is intended to be

used for a reset from a host.

Following the Power-on reset or a reset by POR_EXT, the

system oscillator is started and the SYS_CLK output is

activated (enabled). The SYS_CLK output can be

controlled by the SYS_CLK_REQ signal but only if the ‘rdy’

bit in the Control Register has been set to logic 1.

The function of SYS_CLK_REQ has 2 phases:

1. After reset, SYS_CLK_REQ is not taken into account

for the generation of SYS_CLK. After reset the 13 MHz

system clock is enabled on SYS_CLK.

2. Once the ‘rdy’ bit is set to logic 1, the 13 MHz clock on

the SYS_CLK is controlled with SYS_CLK_REQ.

The SYS_CLK_REQ signal will not control or disable the

oscillator.

The LPO_CLK output is only controlled by the POR_EXT

signal which also controls the POR output. The POR is

activated 4 SYS_CLK cycles after POR_EXT.

handbook, full pagewidth

MGT755

phase 1 Rdy = 0

phase 2 Rdy = 1

POR

VIO_POWER

LPO_CLK

SYS_CLK_REQ

SYS_CLK

OSC

POR_EXT

Fig.4 Reset timing.

PCF26100 Datasheet(PDF) 11 Page - NXP Semiconductors