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Preliminary Information
Replaces X25163/X25165
X5163/X5165
CPU Supervisor with 16Kbit SPI EEPROM
FEATURES
• Selectable watchdog timer
• Low VCC detection and reset assertion
—Five standard reset threshold voltages
—Re-program low VCC reset threshold voltage
using special programming sequence
—Reset signal valid to VCC = 1V
• Determine watchdog or low voltage reset with a
volatile flag bit
• Long battery life with low power consumption
—<50µA max standby current, watchdog on
—<1µA max standby current, watchdog off
—<400µA max active current during read
• 16Kbits of EEPROM
• Built-in inadvertent write protection
—Power-up/power-down protection circuitry
—Protect 0, 1/4, 1/2 or all of EEPROM array with
Block Lockprotection
—In circuit programmable ROM mode
• 2MHz SPI interface modes (0,0 & 1,1)
• Minimize EEPROM programming time
—32-byte page write mode
—Self-timed write cycle
—5ms write cycle time (typical)
• 2.7V to 5.5V and 4.5V to 5.5V power supply
operation
• Available packages
—14-lead TSSOP, 8-lead SOIC
BLOCK DIAGRAM
DESCRIPTION
These devices combine four popular functions, Power-
on Reset Control, Watchdog Timer, Supply Voltage
Supervision, and Block Lock Protect Serial EEPROM
Memory in one package. This combination lowers
system cost, reduces board space requirements, and
increases reliability.
Applying power to the device activates the power on
reset circuit which holds RESET/RESET active for a
period of time. This allows the power supply and oscilla-
tor to stabilize before the processor can execute code.
The Watchdog Timer provides an independent protection
mechanism for microcontrollers. When the microcon-
troller fails to restart a timer within a selectable time out
interval, the device activates the RESET/RESET signal.
The user selects the interval from three preset values.
Once selected, the interval does not change, even
after cycling the power.
The device’s low VCC detection circuitry protects the
user’s system from low voltage conditions, resetting the
system when VCC falls below the minimum VCC trip point.
RESET/RESET is asserted until VCC returns to proper
operating level and stabilizes. Five industry standard
VTRIP thresholds are available, however, Xicor’s unique
circuits allow the threshold to be reprogrammed to meet
custom requirements or to fine-tune the threshold for
applications requiring higher precision.
WP
SI
SO
SCK
CS/WDI
VCC
Watchdog Transition
Detector
Protect Logic
Data
Register
Command
Decode &
Control
Logic
VCC Threshold
Reset Logic
Status
Register
4K Bits
4K Bits
8K Bits
VTRIP
+
-
Watchdog
Timer Reset
Reset &
Watchdog
Timebase
Power on and
Low Voltage
Reset
Generation
RESET/RESET
X5163 = RESET
X5165 = RESET
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X5163/X5165 – Preliminary Information
PIN DESCRIPTION
Pin Pin
(SOIC/PDIP) TSSOP
11
22
36
47
58
69
7 13
8 14
3-5,10-
12
Name
CS/WDI
SO
WP
VSS
SI
SCK
RESET/
RESET
VCC
NC
Function
Chip Select Input. CS HIGH, deselects the device and the SO output pin is at
a high impedance state. Unless a nonvolatile write cycle is underway, the device
will be in the standby power mode. CS LOW enables the device, placing it in the
active power mode. Prior to the start of any operation after power up, a HIGH to
LOW transition on CS is required
Watchdog Input. A HIGH to LOW transition on the WDI pin restarts the Watch-
dog timer. The absence of a HIGH to LOW transition within the watchdog time
out period results in RESET/RESET going active.
Serial Output. SO is a push/pull serial data output pin. A read cycle shifts data out
on this pin. The falling edge of the serial clock (SCK) clocks the data out.
Write Protect. The WP pin works in conjunction with a nonvolatile WPEN bit to
“lock” the setting of the Watchdog Timer control and the memory write protect bits.
Ground
Serial Input. SI is a serial data input pin. Input all opcodes, byte addresses, and
memory data on this pin. The rising edge of the serial clock (SCK) latches the input
data. Send all opcodes (Table 1), addresses and data MSB first.
Serial Clock. The Serial Clock controls the serial bus timing for data input and out-
put. The rising edge of SCK latches in the opcode, address, or data bits present on
the SI pin. The falling edge of SCK changes the data output on the SO pin.
Reset Output. RESET/RESET is an active LOW/HIGH, open drain output which
goes active whenever VCC falls below the minimum VCC sense level. It will remain
active until VCC rises above the minimum VCC sense level for 200ms. RESET/
RESET goes active if the Watchdog Timer is enabled and CS remains either
HIGH or LOW longer than the selectable Watchdog time out period. A falling
edge of CS will reset the Watchdog Timer. RESET/RESET goes active on power
up at 1V and remains active for 200ms after the power supply stabilizes.
Supply Voltage
No internal connections
PIN CONFIGURATION
CS/WDI
SO
WP
VSS
8-Lead SOIC/PDIP
18
27
3 X5163/65 6
45
VCC
RESET/RESET
SCK
SI
CS/WDI
SO
NC
NC
NC
WP
VSS
14-Lead TSSOP
1 14
2 13
3 12
X5163/65
4 11
5 10
69
78
VCC
RESET/RESET
NC
NC
NC
SCK
SI
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X5163/X5165 – Preliminary Information
PRINCIPLES OF OPERATION
Power On Reset
Application of power to the X5163/X5165 activates a
Power On Reset Circuit. This circuit goes active at 1V
and pulls the RESET/RESET pin active. This signal
prevents the system microprocessor from starting to
operate with insufficient voltage or prior to stabilization
of the oscillator. When VCC exceeds the device VTRIP
value for 200ms (nominal) the circuit releases RESET/
RESET, allowing the processor to begin executing code.
Low Voltage Monitoring
During operation, the X5163/X5165 monitors the VCC
level and asserts RESET/RESET if supply voltage falls
below a preset minimum VTRIP. The RESET/RESET
signal prevents the microprocessor from operating in a
power fail or brownout condition. The RESET/RESET
signal remains active until the voltage drops below 1V.
It also remains active until VCC returns and exceeds
VTRIP for 200ms.
Watchdog Timer
The Watchdog Timer circuit monitors the microproces-
sor activity by monitoring the WDI input. The micropro-
cessor must toggle the CS/WDI pin periodically to
prevent a RESET/RESET signal. The CS/WDI pin
must be toggled from HIGH to LOW prior to the expira-
tion of the watchdog time out period. The state of two
nonvolatile control bits in the Status Register deter-
mine the watchdog timer period. The microprocessor
can change these watchdog bits, or they may be
“locked” by tying the WP pin LOW and setting the
WPEN bit HIGH.
VCC Threshold Reset Procedure
The X5163/X5165 has a standard VCC threshold
(VTRIP) voltage. This value will not change over normal
operating and storage conditions. However, in applica-
tions where the standard VTRIP is not exactly right, or
for higher precision in the VTRIP value, the X5163/
X5165 threshold may be adjusted.
Setting the VTRIP Voltage
This procedure sets the VTRIP to a higher voltage
value. For example, if the current VTRIP is 4.4V and the
new VTRIP is 4.6V, this procedure directly makes the
change. If the new setting is lower than the current set-
ting, then it is necessary to reset the trip point before
setting the new value.
To set the new VTRIP voltage, apply the desired VTRIP
threshold to the VCC pin and tie the CS/WDI pin and
the WP pin HIGH. RESET and SO pins are left uncon-
nected. Then apply the programming voltage VP to
both SCK and SI and pulse CS/WDI LOW then HIGH.
Remove VP and the sequence is complete.
Figure 1. Set VTRIP Voltage
CS
SCK
VP
VP
SI
Resetting the VTRIP Voltage
This procedure sets the VTRIP to a “native” voltage
level. For example, if the current VTRIP is 4.4V and the
VTRIP is reset, the new VTRIP is something less than
1.7V. This procedure must be used to set the voltage to
a lower value.
To reset the VTRIP voltage, apply a voltage between
2.7 and 5.5V to the VCC pin. Tie the CS/WDI pin, the
WP pin, AND THE SCK pin HIGH. RESET and SO
pins are left unconnected. Then apply the program-
ming voltage VP to the SI pin ONLY and pulse CS/WDI
LOW then HIGH. Remove VP and the sequence is
complete.
Figure 2. Reset VTRIP Voltage
CS
SCK VCC
VP
SI
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X5163/X5165 – Preliminary Information
Figure 3. VTRIP Programming Sequence Flow Chart
VTRIP Programming
Execute
Reset VTRIP
Sequence
Set VCC = VCC Applied =
Desired VTRIP
New VCC Applied =
Old VCC applied + Error
Execute
Set VTRIP
Sequence
Apply 5V to VCC
Decrement VCC
(VCC = VCC - 50mV)
New VCC Applied =
Old VCC applied - Error
Execute
Reset VTRIP
Sequence
NO RESET pin
goes active?
YES
Error > -Emax
Emax = Maximum Desired Error
Measured VTRIP
Desired VTRIP
Error > Emax
Error < Emax
DONE
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X5163/X5165 – Preliminary Information
Figure 4. Sample VTRIP Reset Circuit
VTRIP
Adj.
Program
4.7K
+
NC
18
27
3 X5163/65 6
45
NC 4.7K
RESET
NC
VP
10K 10K
Reset VTRIP
Test VTRIP
Set VTRIP
SPI SERIAL MEMORY
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
a Serial Peripheral Interface (SPI) and software proto-
col allowing operation on a simple four-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.
The device is designed to interface directly with the
synchronous Serial Peripheral Interface (SPI) of many
popular microcontroller families. It contains an 8-bit
instruction register that is accessed via the SI input,
with data being clocked in on the rising edge of SCK.
CS must be LOW during the entire operation.
All instructions (Table 1), addresses and data are
transferred MSB first. Data input on the SI line is
latched on the first rising edge of SCK after CS goes
LOW. Data is output on the SO line by the falling edge
of SCK. SCK is static, allowing the user to stop the
clock and then start it again to resume operations
where left off.
Write Enable Latch
The device contains a Write Enable Latch. This latch
must be SET before a Write Operation is initiated. The
WREN instruction will set the latch and the WRDI
instruction will reset the latch (Figure 3). This latch is
automatically reset upon a power-up condition and
after the completion of a valid Write Cycle.
Status Register
The RDSR instruction provides access to the Status
Register. The Status Register may be read at any time,
even during a Write Cycle. The Status Register is for-
matted as follows:
7 6 5 4 32 1 0
WPEN FLB WD1 WD0 BL1 BL0 WEL WIP
The Write-In-Progress (WIP) bit is a volatile, read only
bit and indicates whether the device is busy with an
internal nonvolatile write operation. The WIP bit is read
using the RDSR instruction. When set to a “1”, a non-
volatile write operation is in progress. When set to a
“0”, no write is in progress.
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