SAA2502 查看數據表（PDF） - Philips Electronics

零件编号

产品描述 (功能)

生产厂家

SAA2502

ISO/MPEG Audio Source Decoder

Philips Electronics 

Philips Semiconductors

ISO/MPEG Audio Source Decoder

Preliminary specification

SAA2502

7.2.3.1 XOR mode

PHDIF is the XOR function of SIG and REF. The frequency

is twice the frequency of SIG and REF. The PHDIF output

carries a signal, switching between GND and VDD, with an

average value Vavg which is a function of the phase

difference between SIG and REF (see left part of Fig.6).

The locking range in this mode of operation is maximum

for even values of N3 (180 degrees phase difference) but

less for odd values of N3. It is minimum for N3 = 3

(120 degrees phase difference).

7.2.3.2 Edge triggered mode

PHDIF is only influenced by the rising edges of SIG and

REF. Consequently its frequency is equal to the SIG and

REF frequency.

The electrical behaviour of the PHDIF output pin in this

mode is special:

PHDIF is HIGH from the rising edge of REF to the rising

edge of SIG and 3-stated elsewhere if REF is leading and

PHDIF is low from rising edge of SIG to rising edge of REF

and 3-stated elsewhere if REF is trailing. Therefore PHDIF

is NOT 3-stated during a portion tup of each cycle when it

acts as a pull-up device or during a portion tdown of each

cycle when it acts as a pull-down device (see right part of

Fig.6).

As a result the locking range is always 360 degrees phase

difference. The output behaviour as function of phase

difference is non-symmetrical with reference to the vertical

axis, but a reversed mode is also available (by setting the

control flag PHSRVS).

handbook, full pagewidth

T

t1

1

5/6

t2

XOR mode

PHDIF

T

3-stated

100%

tup

t

edge triggered mode

Vavg

VDD

max

1/6

0

0o

min

180o

360o

REF to SIG phase difference

0%

tdown

100%

−180o

0o

+180o

REF to SIG phase difference

MGE473

1997 Nov 17

Fig.6 PHDIF output behaviour.

10

Share Link: