DP8522AV-25 National Semiconductor, DP8522AV-25 Datasheet - Page 47

• Manufacturer Part Number: DP8522AV-25
• Description: IC CTRLR 4M VRAM 25MHZ 68PLCC
• Manufacturer: National Semiconductor

Specifications of DP8522AV-25

• Controller Type: Video RAM Controller, Drivers
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 68-LCC (J-Lead)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Supply: -
• Voltage - Supply: -
• Interface: -
• Other names: *DP8522AV-25

12 0 Dual Accessing Functions (DP8522A)
12 3 2 LOCK Input
When the LOCK input is asserted the currently granted port
can ‘‘lock out’’ the other port through the insertion of wait
states to that port’s access cycle LOCK does not disable
refreshes it only keeps GRANTB in the same state even if
the other port requests an access as shown in Figure 59
LOCK can be used by either port The user must guarantee
that LOCK is not asserted with Port B granted when
AVSRLRQ is asserted to request a VRAM transfer cycle
FIGURE 58b Wait States during a Port B Access
FIGURE 59 LOCK Function
47
12 4 DUAL PORTING AND VRAM TRANSFER CYCLES
The input AVSRLRQ disables any further internally or exter-
nally requested refreshes or Port B access requests from
being executed The AVSRLRQ input does this by making
the VRAM controller arbitration logic think that a Port A ac-
cess is in progress from the point where the AVSRLRQ in-
put goes low until the VRAM shift register load operation is
completed
(Continued)
TL F 9338 – B3
TL F 9338 – B4