S93WD462_98 Datasheet, PDF (2/14 Pages) Summit Microelectronics, Inc. – Precision Supply-Voltage Monitor and Reset Controller With a Watchdog Timer and 1k-bit Microwire Memory

PIN CONFIGURATION
S93WD462/S93WD463
DIP Package (P)
CS 1
SK 2
DI 3
DO 4
8 VCC
7 RESET
6 RESET
5 GND
SOIC Package (S)
CS 1
SK 2
DI 3
DO 4
8 VCC
7 RESET
6 RESET
5 GND
2029 ILL1.0
PIN FUNCTIONS
Pin Name
CS
SK
DI
DO
V_CC
GND
RESET/RESET
Function
Chip Select
Clock Input
Serial Data Input
Serial Data Output
+2.7 to 6.0V Power Supply
Ground
RESET I/O
DEVICE OPERATION
APPLICATIONS
The S93WD462/WD463 is ideal for applications requir-
ing low voltage and low power consumption. This device
provides microcontroller RESET control and can be
manually resettable.
RESET CONTROLLER DESCRIPTION
The S93WD462/WD463 provides a precision reset con-
troller that ensures correct system operation during
brown-out and power-up/-down conditions. It is config-
ured with two open drain reset outputs; pin 7 is an active
high output and pin 6 is an active low output.
During power-up, the reset outputs remain active until
VCC reaches the VTRIP threshold. The outputs will con-
tinue to be driven for approximately 150 ms after reach-
ing VTRIP. The reset outputs will be valid so long as VCC
is ≥ 1.0V. During power-down, the reset outputs will
begin driving active when VCC falls below VTRIP.
The reset pins are I/Os; therefore, the S93WD462/
WD463 can act as a signal conditioning circuit for an
externally applied reset. The inputs are edge triggered;
that is, the RESET input will initiate a reset timeout after
detecting a low to high transition and the RESET input
will initiate a reset timeout after detecting a high to low
transition. Refer to the applications Information section
for more details on device operation as a debounce/
reset extender circuit.
It should be noted the reset outputs are open drain.
When used as outputs driving a circuit they need to be
either tied high (RESET) or tied to ground (RESET)
through the use of pull-up or pull-down resistors. Refer
to the applications aid section for help in determining the
value of resistor to be used. Internally these pins are
weakly pulled up (RESET) and pulled down (RESET):
therefore, if the signals are not being used the pins may
be left unconnected.
WATCHDOG TIMER DESCRIPTION
The S93WD462/WD463 has a watchdog timer with a
nominal timeout period of 1.6 seconds. Whenever the
watchdog times out, it will generate a reset output to both
pins 6 and 7. The watchdog timer is reset by any
transition on CS.
The watchdog timer will be held in a reset state during
power-on while VCC is less than VTRIP. Once VCC
exceeds VTRIP the watchdog will continue to be held in
a reset state for the tPURST period. After tPURST it will be
released and the timer will begin operation. If either reset
input is asserted the watchdog timer will be reset and
remain in the reset condition until either tPURST has
expired or the reset input is released, whichever is
longer.
GENERAL OPERATION
The S93WD462/WD463 is a 1024-bit nonvolatile memory
intended for use with industry standard microproces-
sors. The S93WD463 is organized as X16, seven 9-bit
instructions control the reading, writing and erase
operations of the device. The S93WD462 is organized
as X8, seven 10-bit instructions control the reading,
writing and erase operations of the device. The device
operates on a single 3V or 5V supply and will generate
2029-01 4/14/98
2