X40431 XICOR [Xicor Inc.], X40431 Datasheet - Page 3

• Manufacturer Part Number: X40431
• Description: 4kbit EEPROM, Triple Voltage Monitor with Integrated CPU Supervisor
• Manufacturer: XICOR [Xicor Inc.]

X40430/X40431 – Preliminary Information
PIN DESCRIPTION (Continued)
PRINCIPLES OF OPERATION
Power On Reset
Applying power to the X40430/31 activates a Power
On Reset Circuit that pulls the RESET/RESET pins
active. This signal provides several benefits.
– It prevents the system microprocessor from starting
– It prevents the processor from operating prior to sta-
– It allows time for an FPGA to download its configura-
– It prevents communication to the EEPROM, greatly
When V
for t
(X40431) and RESET (X40430) pin allowing the system
to begin operation.
REV 1.2.3 11/28/00
Pin
to operate with insufficient voltage.
bilization of the oscillator.
tion prior to initialization of the circuit.
reducing the likelihood of data corruption on power up.
10
11
12
13
14
8
9
PURST
CC
V3MON
V3FAIL
Name
WDO
SDA
SCL
V
(selectable) the circuit releases the RESET
WP
exceeds the device V
CC
Serial Data. SDA is a bidirectional pin used to transfer data into and out of the device. It has an
open drain output and may be wire ORed with other open drain or open collector outputs. This pin
requires a pull up resistor and the input buffer is always active (not gated).
Watchdog Input. A HIGH to LOW transition on the SDA (while SCL is toggled from HIGH to LOW
and followed by a stop condition) restarts the Watchdog timer. The absence of this transition within
the watchdog time out period results in WDO going active.
Serial Clock. The Serial Clock controls the serial bus timing for data input and output.
Write Protect. WP HIGH prevents writes to any location in the device (including all the registers).
It has an internal pull down resistor.
V3 Voltage Monitor Input. When the V3MON input is less than the V
LOW. This input can monitor an unregulated power supply with an external resistor divider or can
monitor a third power supply with no external components. Connect V3MON to V
not used.
V3 Voltage Fail Output. This open drain output goes LOW when V3MON is less than V
goes HIGH when V3MON exceeds V
WDO Output. WDO is an active LOW, open drain output which goes active whenever the watch-
dog timer goes active.
Supply Voltage
TRIP1
threshold value
www.xicor.com
TRIP3
Figure 1. Connecting a Manual Reset Push-Button
Manual Reset
By connecting a push-button directly from MR to
ground, the designer adds manual system reset capa-
bility. The MR pin is LOW while the push-button is
closed and RESET/RESET pin remains HIGH/LOW
until the push-button is released and for t
after.
. There is no power up reset delay circuitry on this pin.
Function
System
Reset
RESET
Characteristics subject to change without notice.
X40430
MR
TRIP3
voltage, V3FAIL goes
V
CC
SS
or
PURST
V
Manual
Reset
TRIP3
CC
when
there-
3 of 24
and