ZL50115 ZARLINK [Zarlink Semiconductor Inc], ZL50115 Datasheet - Page 90

• Manufacturer Part Number: ZL50115
• Description: 32, 64 and 128 Channel CESoP Processors
• Manufacturer: ZARLINK [Zarlink Semiconductor Inc]

14.2
The CPU_TA output signal from the ZL5011x is a critical handshake signal to the CPU that ensures the correct
completion of a bus transaction between the two devices. As the signal is critical, it is recommend that the circuit
shown in Figure 47 is implemented in systems operating above 40 MHz bus frequency to ensure robust operation
under all conditions.
The following external logic is required to implement the circuit:
•
•
•
•
The function of the circuit is to extend the TA signal, to ensure the CPU correctly registers it. Resistor R2 must be
fitted to ensure correct operation of the TA input to the processor. It is recommended that the logic is fitted close to
the ZL5011x and that the clock to the 74LCX74 is derived from the same clock source as that input to the ZL5011x.
74LCX74 dual D-type flip-flop (one section of two)
74LCX08 quad AND gate (one section of four)
74LCX125 quad tri-state buffer (one section of four)
4K7 resistor x2
CPU TA Output
CPU_CLK
to ZL5011x
CPU_TA
from ZL5011x
+
3V3
ZL50115/16/17/18/19/20
Figure 47 - CPU_TA Board Circuit
4K7
R1
D
Zarlink Semiconductor Inc.
Q
90
CPU_CS
to ZL5011x
+3V3
4K7
R2
CPU_TA
to CPU
Data Sheet