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®
Data Sheet
X40410, X40411, X40414, X40415
4kbit EEPROM
March 28, 2005
FN8116.0
Dual Voltage Monitor with Integrated CPU
Supervisor
FEATURES
• Dual voltage detection and reset assertion
—Standard reset threshold settings
See Selection table on page 2.
—Adjust low voltage reset threshold voltages
using special programming sequence
—Reset signal valid to VCC = 1V
—Monitor three voltages or detect power fail
• Independent Core Voltage Monitor (V2MON)
• 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)
• Low power CMOS
—25µA typical standby current, watchdog on
—6µA typical standby current, watchdog off
• 4Kbits of EEPROM
—16 byte page write mode
—5ms write cycle time (typical)
www.DataSheet4U.com
• Built-in inadvertent write protection
—Power-up/power-down protection circuitry
—Block lock protect none or 1/2 of EEPROM
• 400kHz 2-wire interface
• 2.7V to 5.5V power supply operation
BLOCK DIAGRAM
• Available packages
—8-lead SOIC, TSSOP
• Monitor Voltages: 5V to 0.9V
• Memory Security
• Independent Core Voltage Monitor
APPLICATIONS
• Communication Equipment
—Routers, Hubs, Switches
—Disk Arrays, Network Storage
• Industrial Systems
—Process Control
—Intelligent Instrumentation
• Computer Systems
— Computers
—Network Servers
DESCRIPTION
The X40410/11/14/15 combines power-on reset con-
trol, watchdog timer, supply voltage supervision, and
secondary voltage supervision, and Block Lockpro-
tect serial EEPROM in one package. This combination
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 oscilla-
SDA
SCL
VCC
(V1MON)
V2MON
Data
Register
Command
Decode Test
& Control
Logic
Threshold
Reset Logic
Fault Detection
Register
Status
Register
EEPROM
Array
Watchdog Timer
and
Reset Logic
User Programmable
VTRIP1
User Programmable
VTRIP2
+
-
VCC or
+ V2MON
Power-on,
Low Voltage
Reset
Generation
-
*X40410/11= V2MON*
X40414/15 = VCC
WDO
RESET
X40410/14
RESET
X40411/15
V2FAIL
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-352-6832 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2005. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.

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X40410, X40411, X40414, X40415
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/RE-
SET 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 com-
mon low voltage combinations are available, however,
Intersil’s unique circuits allows the threshold for either
voltage monitor to be reprogrammed to meet special
needs or to fine-tune the threshold for applications re-
quiring higher precision.
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 Intersil’s Block Lock protection.
The array is internally organized as x 8. The device
features a 2-wire interface and software protocol
allowing operation on an I2C® bus.
The device utilizes Intersil’s proprietary Direct Write
cell, providing a minimum endurance of 100,000
cycles and a minimum data retention of 100 years.
Triple Voltage Monitors
Device
X4040/11
-A
-B
-C
X40414/15
-A
-B
-C
Expected System Voltages
5V; 3V or 3.3V
5V; 3V
3V; 3.3V; 1.8V
3V; 3.3V; 1.5V
3V; 1.5V
3V or 3.3V; 1.1 or 1.2V
Vtrip1(V)
2.0–4.75*
4.55–4.65*
4.35–4.45*
2.85–2.95*
2.0–4.75*
2.85–2.95*
2.55–2.65*
2.85–2.95*
*Voltage monitor requires VCC to operation. Others are independent of VCC.
Vtrip2(V)
1.70–4.75
2.85–2.95
2.55–2.65
1.65–1.75
0.90–3.50*
1.25–1.35*
1.25–1.35*
0.95–1.05*
POR (system)
RESET = X40410
RESET = X40411
RESET = X40414
RESET = X40415
PIN CONFIGURATION
X40410/14, X40411/15
8-Pin SOIC
V2FAIL 1
V2MON 2
8 VCC
7 WDO
RESET/RESET
VSS
3
4
6 SCL
5 SDA
X40410/14, X40411/15
8-Pin TSSOP
WDO
VCC
V2FAIL
V2MON
1
2
3
4
8 SCL
7 SDA
6 VSS
5 RESET/RESET
PIN DESCRIPTION
Pin
SOIC TSSOP Name
Function
1 3 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 4 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.The V2MON comparator is supplied by V2MON (X40410/11) or by VCC Input (X40414/15).
3 5 RESET/ RESET Output. (X40411/15) This is an active LOW, open drain output which goes active whenever
RESET VCC falls below VTRIP1. It will remain active until VCC rises above VTRIP1 and for the tPURST thereafter.
RESET Output. (X40410/14) This is an active HIGH CMOS output which goes active whenever VCC
falls below VTRIP1. It will remain active until VCC rises above VTRIP1 and for the tPURST thereafter.
4 6 VSS Ground
5 7 SDA 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 transi-
tion within the watchdog time out period results in WDO going active.
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X40410, X40411, X40414, X40415
PIN DESCRIPTION (Continued)
Pin
SOIC TSSOP
68
71
82
Name
SCL
WDO
VCC
Function
Serial Clock. The Serial Clock controls the serial bus timing for data input and output.
WDO Output. WDO is an active LOW, open drain output which goes active whenever the watch-
dog timer goes active.
Supply Voltage
PRINCIPLES OF OPERATION
Power-On Reset
Application of power to the X40410/11/14/15 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 to
operate with insufficient voltage.
– It prevents the processor from operating prior to stabili-
zation of the oscillator.
– It allows time for an FPGA to download its configura-
tion prior to initialization of the circuit.
– It prevents communication to the EEPROM, greatly
reducing the likelihood of data corruption on power-up.
When VCC exceeds the device VTRIP1 threshold value for
tPURST (selectable) the circuit releases the RESET
(X40411) and RESET (X40410) pin allowing the system
to begin operation.
For the X40414/15 devices, the V2FAIL signal remains
actice until VCC drops below 1Vx and remains active
until V2MON returns and exceeds VTRIP2. This sense
circuitry is powered by VCC. If VCC = 0, V2MON cannot
be monitored.
Figure 1. Two Uses of Multiple Voltage Monitoring
X40411-A
VCC V2MON
6–10V
1M
1M
5V VCC
Reg RESET
V2MON
(2.9V)
V2FAIL
System
Reset
Resistors selected so 3V appears on V2MON when unregulated
supply reaches 6V.
Low Voltage VCC (V1 Monitoring)
During operation, the X40410/11/14/15 monitors the
VCC level and asserts RESET/RESET if supply voltage
falls below a preset minimum VTRIP1. The
RESET/RESET signal prevents the microprocessor
from operating in a power fail or brownout condition.
The V1FAIL signal remains active until the voltage
drops below 1V. It also remains active until VCC returns
and exceeds VTRIP1 for tPURST.
Low Voltage V2 Monitoring
The X40410/11/14/15 also monitors a second voltage
level and asserts V2FAIL if the voltage falls below a
preset minimum VTRIP2. The V2FAIL signal is either
ORed with RESET to prevent the microprocessor from
operating in a power fail or brownout condition or used to
interrupt the microprocessor with notification of an
impending power failure. For the X40410/11 the V2FAIL
signal remains active until the VCC drops below 1V (VCC
falling). It also remains active until V2MON returns and
exceeds VTRIP2 by 0.2V. This voltage sense circuitry
monitors the power supply connected to the V2MON pin.
If VCC = 0, V2MON can still be monitored.
Unreg.
Supply
3.3V
Reg
1.2V
Reg
X40414-C
VCC
VCC
RESET
V2MON
V2FAIL
System
Reset
Notice: No external components required to monitor two voltages.
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X40410, X40411, X40414, X40415
Figure 2. VTRIPX Set/Reset Conditions
VTRIPX
(X = 1, 2)
VCC/V2MON
WDO
VP
SCL 0
70
70
7
SDA
A0h
WATCHDOG TIMER
The Watchdog Timer circuit monitors the microprocessor
activity by monitoring the SDA and SCL pins. The micro-
processor must toggle the SDA pin HIGH to LOW period-
ically, while SCL also toggles from HIGH to LOW (this is
a start bit) followed by a stop condition prior to the expira-
tion of the watchdog time out period to prevent a WDO
signal going active. The state of two nonvolatile control
bits in the Status Register determines the watchdog timer
period. The microprocessor can change these watchdog
bits by writing to the X40410/11/14/15 control register
(also refer to page 19).
Figure 3. Watchdog Restart
.6µs
1.3µs
SCL
SDA
Timer Start
V1 AND V2 THRESHOLD PROGRAM PROCEDURE
(OPTIONAL)
The X40410/11/14/15is shipped with standard V1 and
V2 threshold (VTRIP1, VTRIP2) voltages. These values
will not change over normal operating and storage
conditions. However, in applications where the stan-
dard thresholds are not exactly right, or if higher preci-
sion is needed in the threshold value, the
X40410/11/14/15 trip points may be adjusted. The pro-
cedure is described below, and uses the application of
a high voltage control signal.
4
00h tWC
Setting a VTRIPx Voltage (x = 1, 2)
There are two procedures used to set the threshold
voltages (VTRIPx), depending if the threshold voltage
to be stored is higher or lower than the present value.
For example, if the present VTRIPx is 2.9 V and the
new VTRIPx is 3.2 V, the new voltage can be stored
directly into the VTRIPx cell. If however, the new setting
is to be lower than the present setting, then it is neces-
sary to “reset” the VTRIPx voltage before setting the
new value.
Setting a Higher VTRIPx Voltage (x = 1, 2)
To set a VTRIPx threshold to a new voltage which is
higher than the present threshold, the user must apply
the desired VTRIPx threshold voltage to the corre-
sponding input pin Vcc(V1MON), or V2MON. The
Vcc(V1MON) and V2MON must be tied together dur-
ing this sequence. Then, a programming voltage (Vp)
must be applied to the WDO pin before a START con-
dition is set up on SDA. Next, issue on the SDA pin the
Slave Address A0h, followed by the Byte Address 01h
for VTRIP1 and 09h for VTRIP2, and a 00h Data Byte in
order to program VTRIPx. The STOP bit following a
valid write operation initiates the programming
sequence. Pin WDO must then be brought LOW to
complete the operation.
Note: This operation does not corrupt the memory
array.
Setting a Lower VTRIPx Voltage (x = 1, 2)
In order to set VTRIPx to a lower voltage than the
present value, then VTRIPx must first be “reset” accord-
ing to the procedure described below. Once VTRIPx
has been “reset”, then VTRIPx can be set to the desired
voltage using the procedure described in “Setting a
Higher VTRIPx Voltage”.
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X40410, X40411, X40414, X40415
Resetting the VTRIPx Voltage
To reset a VTRIPx voltage, apply the programming volt-
age (Vp) to the WDO pin before a START condition is
set up on SDA. Next, issue on the SDA pin the Slave
Address A0h followed by the Byte Address 03h for
VTRIP1 and 0Bh for VTRIP2, followed by 00h for the
Data Byte in order to reset VTRIPx. The STOP bit fol-
lowing a valid write operation initiates the program-
ming sequence. Pin WDO must then be brought LOW
to complete the operation.
After being reset, the value of VTRIPx becomes a nomi-
nal value of 1.7V or lesser.
Note: This operation does not corrupt the memory
array.
CONTROL REGISTER
The Control Register provides the user a mechanism for
changing the Block Lock and Watchdog Timer settings.
The Block Lock and Watchdog Timer bits are nonvolatile
and do not change when power is removed.
The Control Register is accessed with a special pream-
ble in the slave byte (1011) and is located at address
1FFh. It can only be modified by performing a byte write
operation directly to the address of the register and only
one data byte is allowed for each register write operation.
Prior to writing to the Control Register, the WEL and
RWEL bits must be set using a two step process, with
the whole sequence requiring 3 steps. See "Writing to
the Control Registers" on page 7.
The user must issue a stop, after sending this byte to
the register, to initiate the nonvolatile cycle that stores
WD1, WD0, PUP1, PUP0, BP1, and BP0. The
X40410/11/14/15 will not acknowledge any data bytes
written after the first byte is entered.
The state of the Control Register can be read at any
time by performing a random read at address 01Fh,
using the special preamble. Only one byte is read by
each register read operation. The master should sup-
ply a stop condition to be consistent with the bus pro-
tocol, but a stop is not required to end this operation.
765 4
PUP1 WD1 WD0 BP
3 2 10
0 RWEL WEL PUP0
RWEL: Register Write Enable Latch (Volatile)
The RWEL bit must be set to “1” prior to a write to the
Control Register.
Figure 4. Sample VTRIP Reset Circuit
VTRIP1
Adj.
V2FAIL
RESET
VTRIP2
Adj.
4.7K
1
3 SOIC
2 X4041x
4
8
7
6
5
VP
Adjust
Run
µC
SCL
SDA
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