Cypress CY14B256K manual Features, Functional Description, Logic Block Diagram

CY14B256K

256 Kbit (32K x 8) nvSRAM with Real Time Clock

Features

■25 ns, 35 ns, and 45 ns access times

■Pin compatible with STK17T88

■Data integrity of Cypress nvSRAM combined with full featured Real Time Clock

❐Low power, 350 nA RTC current

❐Capacitor or battery backup for RTC

■Watchdog timer

■Clock alarm with programmable interrupts

■Hands off automatic STORE on power down with only a small capacitor

■STORE to QuantumTrap™ initiated by software, device pin, or on power down

■RECALL to SRAM initiated by software or on power up

■Infinite READ, WRITE, and RECALL cycles

■High reliability

❐Endurance to 200K cycles

❐Data retention: 20 years at 55°C

■Single 3V operation with tolerance of +20%, -10%

■Commercial and industrial temperature

■48-Pin SSOP (ROHS compliant)

Functional Description

The Cypress CY14B256K combines a 256 Kbit nonvolatile static RAM with a full-featured real time clock in a monolithic integrated circuit. The embedded nonvolatile elements incorporate QuantumTrap technology producing the world’s most reliable nonvolatile memory. The SRAM is read and written an infinite number of times, while independent, nonvolatile data resides in the nonvolatile elements.

The real time clock function provides an accurate clock with leap year tracking and a programmable high accuracy oscillator. The alarm function is programmable for one time alarms or periodic seconds, minutes, hours, or days. There is also a programmable watchdog timer for process control.

Logic Block Diagram

		QuantumTrap	VCC	VCAP
		512 X 512	POWER		VRTCbat
A5	DECODER	STORE	CONTROL		VRTCcap
A6
A7		RECALL	STORE/
A8
		STATIC RAM	RECALL			HSB
A9		ARRAY
			CONTROL
A11	ROW	512 X 512
A12
A13				SOFTWARE		A13 - A0
A14
				DETECT
DQ0		COLUMN IO
DQ1	BUFFERS	COLUMN DEC
DQ2						x1
DQ3				RTC		x2
DQ4						INT
	INPUT
DQ5		A0 A1 A2 A3 A4 A10
DQ6
DQ7				MUX		A14 - A0
						OE
						CE
						WE

Cypress Semiconductor Corporation • 198 Champion Court	•	San Jose, CA 95134-1709	•	408-943-2600
Document Number: 001-06431 Rev. *H		Revised February 24, 2009

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