Download Small Outline J-lead

Interfacing External Memory
Rajiv Nandivada
Types of Memory
•
•
•
•
•
DRAM
SRAM
EPROM
EEPROM
FLASH MEMORY
High Level Schematic
Clock cycle of 10-20 ns (Depending on its use).
3.3 V CMOS SRAM (128 x 8 bit).
Uses multiplexed address and data bus to reduce the number of port pins.
The lower address bits are held in latch while the data is transferred.
Functional Block Diagram of SRAM
Single 3.3 V supply.
Lower power consumption via chip deselect.
Available in 32 pin Plastic SOJ, and 32 pin Type II TSOP packages.
Pin Configuration
SOJ and TSOP Top View
SOJ: Small Outline J Leads
TSOP: Thin Small Outline Package
Characteristics
Symbol
VDD
Rating
Supply voltage
relative to GND
Value
Unit
-0.5 to +4.6
V
VIN,VOUT
Terminal voltage
relative to GND
-0.5 to VDD +0.5
V
TA
Commercial
Operating Temp
0 to +70
0C
Industrial
Operating Temp
-40 to +85
0C
TBIAS
Temperature under
bias
-55 to +125
0C
TSTG
Storage
Temperature
-55 to +125
0C
PT
Power Dissipation
1.25
W
IOUT
DC Output Current
50
mA
Truth Table
Timing Diagrams
Read cycle:
Write cycle:
Major Manufacturers of SRAM
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Alliance,
Brilliance
Crosslink
Cypress Semiconductor
Dense-PAC Micro
Etron Technology
Eureka
Hitachi
IBM
IDT (Integrated Device Technologies)
Mitsubishi
NEC
Samsung
Seiko Epson
Sharp
Sony
Toshiba
Electrically Erasable Programmable Read-only Memory (EEPROM)
Erasable Programmable Read-only Memory (EPROM)
Flash Memory
I2C(Inter IC) Bus
SDA: Serial Data Line
SCL: Serial Clock Line
Packaging





SOJ or Small Outline J-lead
TSOP or Thin Standard Outline Package
DIP or Dual Inline Package
ZIP or Zigzag Inline Package
PLCC or Plastic Leaded Chip Carrier
Packaging Contd..

SOJ or Small Outline J-lead

TSOP or Thin Standard Outline Package

DIP or Dual Inline Package

ZIP or Zigzag Inline Package

PLCC or Plastic Leaded Chip Carrier
Pricing
Depends on
•
•
•
•
•
•
The type of package it comes in (DIP, SOJ, TSOP)
The speed of the memory.
The market value.
The vendor (Digikey, Jameco)
Storage capacity( 128K X 8, 256K X 8)
The type of memory (Flash, EEPROM)
References
•
•
•
•
•
•
www.cygnal.com
www.digikey.com
www.srams.co.uk
www.jameco.com
www.atmel.com
www.xicor.com