Cypress CY14B256K - Manual
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Table of Contents:
- Page 2 – Top View
- Page 3 – Device Operation; SRAM READ; Figure 2. AutoStore Mode
- Page 5 – Low Average Active Power; Figure 3; Best Practices; Stopping and Starting the Oscillator; Figure 3. Current versus Cycle Time
- Page 7 – Real Time Clock Operation; Register Map Detail; Table 2. RTC Backup Time
- Page 8 – Calibrating the Clock; Alarm; Note; Watchdog Timer; Figure 4
- Page 9 – Power Monitor; “AutoStore® Operation”; Interrupts; Watchdog Interrupt Enable - WIE; Flags Register; “Stopping and Starting the Oscillator”; Figure 4. Watchdog Timer Block Diagram
- Page 10 – WDF - Watchdog Timer Flag
- Page 13 – WatchDog Timer; “Watchdog; Interrupt Status/Control
- Page 14 – Table 4. Register Map Detail
- Page 15 – DC Electrical Characteristics
- Page 16 – Thermal Resistance; AC Test Conditions
- Page 17 – AC Switching Characteristics
- Page 19 – AutoStore or Power Up RECALL; Parameter
- Page 20 – Software Controlled STORE/RECALL Cycles
- Page 21 – Hardware STORE Cycle; Time Allowed to Complete SRAM Cycle; Hardware STORE Pulse Width; Soft Sequence Commands; Soft Sequence Processing Time
- Page 22 – RTC Characteristics; Truth Table For SRAM Operations
- Page 23 – Part Numbering Nomenclature; Cypress
- Page 24 – Ordering Information
- Page 25 – Package Diagrams
- Page 26 – Document History Page; ECN
CY14B256K
256 Kbit (32K x 8) nvSRAM with Real Time Clock
Cypress Semiconductor Corporation
•
198 Champion Court
•
San Jose
,
CA 95134-1709
•
408-943-2600
Document Number: 001-06431 Rev. *H
Revised February 24, 2009
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.
STORE/
RECALL
CONTROL
POWER
CONTROL
SOFTWARE
DETECT
STATIC RAM
ARRAY
512 X 512
QuantumTrap
512 X 512
STORE
RECALL
COLUMN IO
COLUMN DEC
ROW DECODER
INPUT
BUFFERS
OE
CE
WE
HSB
V
CC
V
CAP
A
13
-
A
0
A
0
A
1
A
2
A
3
A
4
A
10
A
5
A
6
A
7
A
8
A
9
A
12
A
13
A
14
DQ
0
DQ
1
DQ
2
DQ
3
DQ
4
DQ
5
DQ
6
DQ
7
RTC
MUX
A
14
-
A
0
x
1
x
2
INT
V
RTCbat
V
RTCcap
A
11
Logic Block Diagram
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Summary
CY14B256K Document Number: 001-06431 Rev. *H Page 2 of 28 Pin Configurations Figure 1. 48-Pin SSOP Pin Definitions Pin Name Alt IO Type Description A 0 –A 14 Input Address Inputs. Used to select one of the 32,768 bytes of the nvSRAM. DQ0-DQ7 Input or Output Bidirectional Data IO lines . Used as inpu...
CY14B256K Document Number: 001-06431 Rev. *H Page 3 of 28 Device Operation The CY14B256K nvSRAM consists of two functionalcomponents paired in the same physical cell. The componentsare SRAM memory cell and a nonvolatile QuantumTrap cell. TheSRAM memory cell operates as a standard fast static RAM. Da...
CY14B256K Document Number: 001-06431 Rev. *H Page 5 of 28 Low Average Active Power CMOS technology provides the CY14B256K the benefit ofdrawing significantly less current when it is cycled at times longerthan 50 ns. Figure 3 shows the relationship between I CC and READ and/or WRITE cycle time. Worst...
