X40421 Monitor Datasheet

X40421 Datasheet, PDF, Equivalent


Part Number

X40421

Description

(X40420 / X40421) Dual Voltage Monitor

Manufacture

Xicor

Total Page 25 Pages
Datasheet
Download X40421 Datasheet


X40421
New Features
• Monitor Voltages: 5V to 1.6V
• Memory Security
• Battery Switch Backup
• VOUT 5mA to 50mA
Preliminary Datasheet
4kbit EEPROM
X40420/X40421
Dual Voltage Monitor with Integrated CPU Supervisor and System Battery Switch
FEATURES
• Dual voltage detection and reset assertion
—Three standard reset threshold settings
(4.6V/2.9V, 4.6V/2.6V, 2.9V/1.6V)
—VTRIP2 Programmable down to 0.9V
—Adjust low voltage reset threshold voltages
using special programming sequence
—Reset signal valid to VCC = 1V
—Monitor two voltages or detect power fail
• Battery Switch Backup
• VOUT: 5mA to 50mA from VCC; or 250µA from
VBATT
• Fault detection register
• Selectable power on reset timeout
(0.05s, 0.2s, 0.4s, 0.8s)
• Selectable watchdog timer interval
(25ms, 200ms, 1.4s, off)
• Debounced manual reset input
• Low power CMOS
—25µA typical standby current, watchdog on
—6µA typical standby current, watchdog off
—1µA typical battery current in backup mode
www.DataSheet4U.com 4Kbits of EEPROM
—16 byte page write mode
—Self-timed write cycle
—5ms write cycle time (typical)
• Built-in inadvertent write protection
—Power-up/power-down protection circuitry
—Block lock protect 0 or 1/2, of EEPROM
• 400kHz 2-wire interface
• 2.7V to 5.5V power supply operation
• Available packages
—14-lead SOIC, TSSOP
APPLICATIONS
• Communications Equipment
—Routers, Hubs, Switches
—Disk arrays
• Industrial Systems
—Process Control
—Intelligent Instrumentation
• Computer Systems
—Desktop Computers
—Network Servers
X40420/21
Standard VTRIP1 Level Standard VTRIP2 Level
4.6V (+/-1%)
2.9V(+/-1.7%)
4.6V (+/-1%)
2.6V (+/-2%)
2.9V(+/-1.7%)
1.6V (+/-3%)
See “Ordering Information” for more details
For Custom Settings, call Xicor.
Suffix
-A
-B
-C
DESCRIPTION
The X40420/21 combines power-on reset control,
watchdog timer, supply voltage supervision, and sec-
ondary supervision, manual reset, and Block Lock
protect serial EEPROM in one package. This combina-
tion lowers system cost, reduces board space require-
ments, and increases reliability.
Applying voltage to VCC activates the power on reset
circuit which holds RESET/RESET active for a period of
time. This allows the power supply and system oscillator
to stabilize before the processor can execute code.
BLOCK DIAGRAM
V2MON
SDA
WP
SCL
VCC
(V1MON)
BATT-ON
VOUT
VBATT
REV 1.2.14 7/12/02
Data
Register
Command
Decode Test
& Control
Logic
System
Battery
Switch
V2 Monitor
Logic
VOUT
+
VTRIP2
-
Fault Detection
Register
Status
Register
EEPROM
Array
VCCLoMgoicnitor
VOUT
+
VTRIP1
-
Watchdog
and
Reset Logic
Power on,
Manual Reset
Low Voltage
Reset
Generation
VOUT
V2FAIL
WDO
MR
RESET
X40420
RESET
X40421
LOWLINE
www.xicor.com
Characteristics subject to change without notice. 1 of 25

X40421
X40420/X40421 – Preliminary
Low VCC detection circuitry protects the user’s system
from low voltage conditions, resetting the system when
VCC falls below the minimum VTRIP1 point. RESET/
RESET is active until VCC returns to proper operating
level and stabilizes. A second voltage monitor circuit
tracks the unregulated supply to provide a power fail
warning or monitors different power supply voltage.
Three common low voltage combinations are available,
however, Xicor’s unique circuits allows the threshold for
either voltage monitor to be reprogrammed to meet
special needs or to fine-tune the threshold for applica-
tions requiring higher precision.
A manual reset input provides debounce circuitry for
minimum reset component count.
A battery switch circuit compares VCC with VBATT input
and connects VOUT to whichever is higher. This pro-
vides voltage to external SRAM or other circuits in the
event of main power failure. The X40420/21 can drive
50mA from VCC to 250µA from VBATT. The device only
switches to VBATT when VCC drops below the low VCC
voltage threshold and VBATT.
The Watchdog Timer provides an independent protec-
tion mechanism for microcontrollers. When the micro-
controller fails to restart a timer within a selectable time
out interval, the device activates the WDO signal. The
user selects the interval from three preset values. Once
selected, the interval does not change, even after
cycling the power.
The memory portion of the device is a CMOS Serial
EEPROM array with Xicor’s Block Lock protection. The
array is internally organized as x 8. The device features
an 2-wire interface and software protocol allowing
operation on a two-wire bus.
The device utilizes Xicor’s proprietary Direct Write
cell, providing a minimum endurance of 100,000 cycles
and a minimum data retention of 100 years.
Example Application
Unreg.
Supply
5V
REG
BATT-ON
VCC
VBATT VOUT
+
X40420/21
V2MON
V2FAIL
VDO
RESET
MR
SCL SDA
Enable
SRAM
Addr
Manual
Reset
Addr
uC
NMI
IRQ VCC
RESET
I2C
PIN CONFIGURATION
X40420
14-Pin SOIC, TSSOP
V2FAIL 1
V2MON 2
14 VCC
13 BATT-ON
LOWLINE
WDO
MR
RESET
VSS
3
4
5
6
7
12 VOUT
11 VBATT
10 WP
9 SCL
8 SDA
X40421
14-Pin SOIC, TSSOP
V2FAIL
V2MON
LOWLINE
WDO
MR
RESET
VSS
1
2
3
4
5
6
7
14 VCC
13 BATT-ON
12 VOUT
11 VBATT
10 WP
9 SCL
8 SDA
PIN DESCRIPTION
Pin Name
Function
1 V2FAIL V2 Voltage Fail Output. This open drain output goes LOW when V2MON is less than VTRIP2 and
goes HIGH when V2MON exceeds VTRIP2. There is no power up reset delay circuitry on this pin.
2 V2MON V2 Voltage Monitor Input. When the V2MON input is less than the VTRIP2 voltage, V2FAIL goes
LOW. This input can monitor an unregulated power supply with an external resistor divider or can
monitor a second power supply with no external components. Connect V2MON to VSS or VCC
when not used.
3 LOWLINE Early Low VCC Detect. This open drain output signal goes LOW when VCC < VTRIP1.
When VCC > VTRIP1, this pin is pulled high with the use of an external pull up resistor.
REV 1.2.14 7/12/02
www.xicor.com
Characteristics subject to change without notice. 2 of 25


Features New Features • • • • Monitor Vol tages: 5V to 1.6V Memory Security Batte ry Switch Backup VOUT 5mA to 50mA Prel iminary Datasheet 4kbit EEPROM X40420 /X40421 APPLICATIONS • Communications Equipment —Routers, Hubs, Switches Disk arrays • Industrial Systems Process Control —Intelligent Instrum entation • Computer Systems —Deskto p Computers —Network Servers X40420/2 1 Dual Voltage Monitor with Integrated CPU Supervisor and System Battery Swit ch FEATURES • Dual voltage detection and reset assertion —Three standard r eset threshold settings (4.6V/2.9V, 4.6 V/2.6V, 2.9V/1.6V) —VTRIP2 Programmab le down to 0.9V —Adjust low voltage r eset threshold voltages using special p rogramming sequence —Reset signal val id to VCC = 1V —Monitor two voltages or detect power fail • Battery Switch Backup • VOUT: 5mA to 50mA from VCC; or 250µA from VBATT • Fault detecti on register • Selectable power on res et timeout (0.05s, 0.2s, 0.4s, 0.8s) • Selectable watchdog timer interval (25ms, 200ms, 1.4s, off) • Debounced.
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