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May 18, 1998

Hitachi Releases 64-Mbit Synchronous DRAMs that Support CAS Latency of 2 Clock Cycles in 100-MHz Memory Bus Systems and 64-MB and 128-MB Synchronous DRAM Modules Using Those Chips

- A random access time of 36 ns achieved to support high-speed data processing in personal computers and other information-processing equipment -

At the same time, Hitachi also announced the release of four memory modules based on these SDRAMs. Sample shipments of the HB52E88EM-A6D (with a 64-bit organization) and the HB52E89EM-A6D (with a 72-bit organization) 64-MB SDRAM modules and the HB52E168EN-A6D (with a 64-bit organization) and the HB52E169EN-A6D (with a 72-bit organization) 128-MB SDRAM modules, will also begin in June 1998 in Japan.

There are microprocessors used in PCs with clock speeds of over 350 MHz, and memory bus speed of DRAMs used in these PCs is 100-MHz. Hitachi already mass produces 64- Mbit SDRAMs that support a 3-clock cycle CAS latency in 100-MHz systems and is now releasing SDRAMs that support a 2-clock cycle CAS latency.

The HM5264165DTT-A60, the HM5216805DTT-A60, and the HM 5216405DTT-A60 64-Mbit SDRAMs achieve increased speed and reduced current drain by using a 0.25-micrometer CMOS fabrication process and by adopting an internal voltage step-down circuit.

These new products achieve the access time of 6 ns from the clock with a CAS latency of 2 clock cycles. This improves the random access time to 36ns compared to the 46 ns of Hitachi earlier 3-clock cycle CAS latency products.

Furthermore, the burst current (Icc4) of 110 mA in the earlier 8-bit organization products has been reduced by about 36% to 70 mA in the current 8-bit organization products. This can provide reduced current drains in end products. The HM5264165DTT-A60 has a 1-Mword x 16-bit x 4-bank organization, the HM5264805DTT-A60, has a 2-Mword x 8- bit x 4-bank organization, and the HM5264405DTT-A60 has a 4-Mword x 4-bit x 4-bank organization, and thus conform to JEDEC (Joint Electron Device Engineering Council) standards. These products are provided in a 54-pin 400-mil TSOP-II package.

The memory modules also being released use these SDRAMs and 168-pin DIMMs (dual inline memory modules) that support 2-clock cycle CAS latencies in 100-MHz memory bus systems. The products of this release are the HB52E 88 EM-A6D and the HB52E89EM-A6D 64-MB SDRAM modules and the HB52E168EN-A6D and the HB52E169EN-A6D 128-MB SDRAM modules. All of these products conform to the JEDEC standards.

The HB52E88EM-A6D has an 8-Mword x 64-bit x 1-bank organization, whereas the HB52E89EM-A6D has an 8-Mword x 72-bit x 1-bank organization to support ECC^*2. These modules use eight (HB52E88EM-A6D) or nine (HB52E 89EM-A6D) of the HM5264805DTT-A60 8-bit organization SDRAM chips on the printed circuit board. The HB52E168 EN-A6D has an 8-Mword x 64-bit x 2-bank organization, whereas the HB52E169EN-A6D has an 8-Mword x 72-bit x 2- bank organization to support ECC. These modules use 16 (HB52E168EN) or 18 (HB52E169EN) of the HM 5264805DTT-A608-bit organization SDRAM chips on the printed circuit board.

Additionally, the clock interconnect lengths (the distance between the module connections and the individual SDRAM chips) are equalized within the module printed circuit board to minimize clock skew within the module. Also, resistors are inserted in the clock input and data signal lines to suppress signal reflections and allow operation at the high speed of 100 MHz. Note that a 6-layer design was adopted in the printed circuit board used in these modules to allow adequate ground and power planes to be provided. This holds the power supply impedance to a minimum and reduces noise due to high-speed operation.

Note	*1.	CAS latency: Indicates the number of clock cycles from the input of a read command to data output. These products support CAS latencies of 2 and 3 clock cycles.
	*2.	ECC (error checking and correction): Functions that both check for errors that occur in memory data and that correct those errors.

Application Product Examples

Main memory in personal computers, workstations, and other computer systems

Pricing in Japan

- 64-Mbit Synchronous DRAM

Catalog No.	Organization	Sample price (Yen)
HM5264165DTT-A60	1M x 16 bits x 4 banks	2,500
HM5264805DTT-A60	2M x 8 bits x 4 banks	2,500
HM5264405DTT-A60	4M x 4 bits x 4 banks	2,500

- Synchronous DRAM Modules

Catalog No.	Organization	Sample price (Yen)
HB52E88EM-A6D	8M x 64bit	22,000
HB52E89EM-A6D	8M x 72bit	24,500
HB52E168EN-A6D	16M x 64bit	44,000
HB52E169EN-A6D	16M x 72bit	49,000

Features

1. Support for a CAS latency of 2 clock cycles in 100-MHz memory bus systems This allows the construction of even faster systems. These products support 100-MHz memory bus systems.
2. Low power These products can contribute to reductions in the total system power consumption and to longer battery life in portable systems.

1. 64-Mbit Synchronous DRAM

Item		HM5264165DTT-A60	HM5264805DTT-A60	HM5264405DTT-A60
Memory organization		1 Mword x 16 bits x 4 banks	2 Mwords x 8 bits x 4 banks	4 Mwords x 4 bits x 4 banks
External power-supply voltage		3.3 V +/- 0.3 V
High-speed modes		Burst data transfers with burst lengths of 1, 2, 4, 8, or full.
Clock frequency		100 MHz
Access time (tAC)	CL=2	6ns
	CL=3	6ns
Setup and hold times		2ns / 1ns
Current drain (Icc4)	CL=2	80mA	70mA	60mA
	CL=3	100mA	85mA	80mA
Functions		Burst stop Burst read Single write Auto precharge Clock suspend DQM control Self/auto-refresh
Process		0.25-micrometer CMOS process
Package		54-pin 400-mil TSOP-II

2. Synchronous DRAM Modules

Item		HB52E88EM-A6D	HB52E89EM-A6D	HB52E168EN-A6D	HB52E169EN-A6D
Memory organization		8 Mwords x 64 bits	8 Mwords x 72 bits	16 Mwords x 64 bits	16 Mwords x 72 bits
External power-supply voltage		3.3V +/- 0.3V
High-speed modes		Burst data transfers with burst lengths of 1, 2, 4, 8, or full.
Clock frequency		100MHz
Access time (tAC)	CL=2	6ns
	CL=3	6ns
Setup and hold times		2ns / 1ns
Functions		Burst stop Burst read, single write Auto precharge Clock suspend DQM control Self/auto precharge
Package		168-pin DIMM (dual inline memory module) 133.37 x 34.93 x 4.0 mm

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