x4c105 Intersil Corporation, x4c105 Datasheet - Page 2

• Manufacturer Part Number: x4c105
• Description: Cpu Supervisor With Novram And Output Ports
• Manufacturer: Intersil Corporation

PACKAGE/PINOUTS
Pin Names
DEVICE DESCRIPTION
Serial Memory Section
The device contains a 4Kbit EEPROM memory array
with an internal address counter that allows it to be
read sequentially, through its entire address space
after receiving only 1 full address. The serial interface
includes a current address read that requires no input
address, but allows reading of the entire array starting
from the address plus one of the last read or write. The
address counter is also used for the write operation
where the user may enter up to a page of data (16
bytes) after supplying only 1 full address.
RESET
S1, S2
O0-O3
D0-D3
SDA
CAP
SCL
V
V
Pin
WP
WE
OE
CE
SS
CC
RESET
CAP
V
WE
OE
CE
O3
O2
S1
S2
SS
Ground
Serial Data
Power
Serial Clock
Write Protect
Device Select Inputs
External AUTOSTORE Capacitor
NOVRAM I/Os
Low Voltage Detect Output
NOVRAM Chip Enable
NOVRAM Read Signal
NOVRAM Write signal
NOVRAM Outputs
20-Lead TSSOP
1
2
3
4
5
6
7
8
9
10
2
Description
20
19
18
17
16
15
14
13
12
11
V
WP
SCL
SDA
D0
D1
D2
D3
O0
O1
CC
X4C105
A WP pin provides hardware write protection. The WP
pin active (HIGH) prevents writes to the top half of the
memory.
This section is a 4K-bit version of an industry standard
24C04 device.
NOVRAM Section
The X4C105 also contains a single nibble of
NOVRAM, with parallel access. This memory is com-
pletely isolated from the serial memory section. The
NOVRAM is intended to connect to the system mem-
ory bus and uses standard CE, OE, and WE pins to
control access.
A NOVRAM (or nonvolatile RAM) consists of an
SRAM part and an EEPROM part. The SRAM is saved
to EEPROM only when power fails and the EEPROM
is recalled to SRAM only on power-up.
Output Ports
The X4C105 has four output only ports. These are
active whenever power is applied to the device. The
state of the output pin reflects the value in the respec-
tive SRAM bit. As such, these port pins provide a non-
volatile state. The conditions on the pins are restored
when power is re-applied to the device. This can be
valuable as a DIP switch replacement for controlling
the conditions of an ASIC or other system logic.
Low Voltage Detection
When the internal low voltage detect circuitry senses
that V
– The RESET pin goes active.
– The contents of the SRAM are automatically saved
– Internal circuitry switches to provide power for the
— Communication to the device is interrupted and any
to the “shadow” EEPROM.
AUTOSTORE operation from the CAP pin so the
store operation can complete even in the event of a
catastrophic power failure. To insure this, it is rec-
ommended that a 47µF capacitor be used on the
CAP pin. The capacitor is continuously charged dur-
ing normal operation to provide the necessary
charge to complete the store operation. Other inter-
nal circuits are turned off to minimize current con-
sumption during the store operations.
command is aborted. If a serial nonvolatile store is
in progress when power fails, the operation is com-
pleted
AUTOSTORE cycle.
CC
is low, several things happen:
and
is
followed
by
a
NOVRAM
March 18, 2005
FN8124.0