Samsung DVD-808K, Service Manual

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Circuit Descriptions
7-10
Samsung Electronics
7-3-3 Waveform description
The setup time is approx. 18 nsec. at falling edge of ALE(Address Latch Enable) signal, which has enough hold
time.
At power of 5V, the min. setup time of MIC4(TC74AC573) is 5 nsec, and min. hold time is 3 nsec. It can be known
that data input condition meets setup time and hold time. The eye part of input data in falling edge of ALE signal
corresponds to address on the bus where address and data are mixed.
• CH1 : ALE
(MIC4-11, Address Latch Enable Signal)
• CH2 : HAD0-9
(Input data of MIC4, Common bus data)
Fig. 7-14
The inclining and rising part indicate floating range of data bus.
That is, there is no operational problem because micom is time area not to access any devices sharing a common
bus. The waveform is shown to incline and rise by pull-up resistance and capacitance on PCB pattern.
When micom accesses each device sharing bus, it falls the chip select signal of corresponding chip to (CS1 : MIC2-
22, CS2:MIC3-22, /DPCS:MIC6-76, /DVD1CS:BIC1-175) 0 (Low) before trial. So to speak, the bus is used by time-
division as shown in Fig 7-16, 17. Two and more devices can't be accessed simultaneously.
• CH1 : ALE
(MIC4-11, Address Latch Enable Signal)
• CH2 : HAD0-7 (MIC4-2 to 9, Input data)
• CH3 : HA0-7 (MIC4-19 to 12, Output data)
Fig. 7-15
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