Semiconductor Group

8

HYB39S16160CT-6/-7

16MBit Synchronous DRAM

DQM Function

DQM has two functions for data I/O read write operations. During reads, when it turns to high

at a clock timing, data outputs are disabled and become high impedance after two clock delay (DQM

clocks).

Suspend Mode

During normal access mode, CKE is held high and CLK is enabled. When CKE is low, it freezes

the internal clock and extends data read and write operations. One clock delay is required for mode

Power Down

In order to reduce standby power consumption, a power down mode is available. Bringing CKE

low enters the power down mode and all of receiver circuits are gated. All banks must be

precharged before entering this mode. One clock delay is required for mode entry and exit. The

Power Down mode does not perform any refresh operation.

Auto Precharge

Two methods are available to precharge SDRAMs. In an automatic precharge mode, the CAS

timing accepts one extra address, CA10, to determine whether the chip restores or not after the

operation. If CA10 is high when a Read Command is issued, the Read with Auto-Precharge

function is initiated. The SDRAM automatically enters the precharge operation one clock before the

last data out for CAS latency 2 amd two clocks for CAS latency 3. If CAS10 is high when a Write

Command is issued, the Write with Auto-Precharge function is initiated. The SDRAM

automatically enters the precharge operation one clock delay form the last data-in for CAS latencies

Precharge Command

If CA10 is low, the chip needs another way to precharge. In this mode, a separate precharge

command is necessary. When RAS and WE are low and CAS is high at a clock timing, it triggers the

precharge operation. Two address bits, A10 and A11, are used to define banks as shown in the

following list. The precharge command may be applied coincident with the last of burst reads for

CAS Latency = 1 and with the second to the last read data for CAS Latencies = 2 & 3. Writes require

Bank Selection by Address Bits

A10

A11

Bank A Only

Low

Low

Bank B Only

Low

High

Both A and B

High

Don’t Care