bq2205LY
SLUS581 − FEBRUARY 2004
POWER MONITORING AND SWITCHING CONTROLLER
FOR 3.3 V SRAM
FEATURES
D
Power Monitoring and Switching for
D
D
D
D
D
D
D
Non-Volatile Control of SRAMs
Input Decoder Allows Control of 1 or 2 Banks
of SRAM
Write-Protect Control
3-V Primary Cell Input
3.3-V Operation
Reset Output for System Power-On Reset
Less than 20-ns Chip Enable Propagation
Delay
Small 16-Lead TSSOP Package
DESCRIPTION
The CMOS bq2205 SRAM non-volatile controller
with reset provides all the necessary functions for
converting one or two banks of standard CMOS
SRAM into non-volatile read/write memory.
A precision comparator monitors the 3.3-V VCC
input for an out-of-tolerance condition. When
out-of-tolerance is detected, the two conditioned
chip-enable outputs are forced inactive to
write-protect both banks of SRAM.
Power for the external SRAMs, VOUT, is switched
from the VCC supply to the battery-backup supply
as VCC decays. On a subsequent power-up, the
VOUT supply is automatically switched from the
backup supply to the VCC supply. The external
SRAMs are write-protected until a power-valid
condition exists. The reset output provides
power-fail and power-on resets for the system.
During power-valid operation, the input decoder, A,
selects one of two banks of SRAM.
APPLICATIONS
D
NVSRAM Modules
D
Point-of-Sale Systems
D
Facsimile, Printers and Photocopiers
D
Internet Appliances
D
Servers
D
Medical Instrumentation and Industrial
Products
From Address
Selector
bq2205LYPW
BW
15
VCC
VCC
To Microprocessor
Main Supply
VDC
GND
12 VCC
1
A
RST 16
VOUT 13
VCC
CECON1 10
CE
SRAM Bank 1
CECON2 14
UDG−03129
Backup Supply
VDC
GND
11 CE
9 BCP
4
5
8
VSS
VSS
VSS
VCC
Pushbutton
Reset
(Optional)
VCC
CE
SRAM Bank 2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright
2004, Texas Instruments Incorporated
www.ti.com
1
TI [ TEXAS INSTRUMENTS ]
