SP791EK SIPEX [Sipex Corporation], SP791EK Datasheet - Page 3

• Manufacturer Part Number: SP791EK
• Description: Evaluation Board Manual
• Manufacturer: SIPEX [Sipex Corporation]

Pin 10 - LOWLINE - LOWLINE Output goes
low when V
threshold. The output can be used to generate
a NMI (non-maskable interrupt) if the
unregulated supply is inaccessible
Pin 11 - WDI - Watchdog Input. WDI is a three-
level input. If WDI remains either high or low
for longer than the watchdog timeout period,
WDO goes low. WDO remains low until the
next transition at WDI. Leaving WDI
unconnected disables the watchdog function.
WDI connects to an internal voltage divider
between V
1.8V when left unconnected. For a simple check
of watchdog function, connect WDI to either
Probe pins GND or V
a Logic Low and produce pulses at WDPO
every 1.6 seconds. (typically 1.6 seconds unless
an external capacitor is used at the SWT pin).
Pin 12 - CE OUT - Chip-Enable Output. The
Chip-Enable (CE) function CE OUT provides
internal gating of chip enable signals to prevent
erroneous data from corrupting the CMOS RAM
in the event of a power failure. During normal
operation, the CE gate is enabled and all CE
transitions are passed from CE IN to CE OUT.
When Reset is asserted, this path is disabled.
Note that CE OUT goes low (active) only when
CE IN is low and V
old. If CE IN is low when reset is asserted, CE
OUT will stay low for 15us or until CE IN goes
high, whichever occurs first.
Pin 13 - CE IN - Chip-Enable Input. The Input
to chip-enable gating circuit. Connect to GND
or V
Pin 14 - WDO - Watchdog Output. WDO goes
low if WDI remains either high or low longer
than the watchdog timeout period. WDO returns
high on the next transition at WDI. WDO
remains high if WDI is unconnected. WDO is
also high when RESET is asserted.
Pin 15 - RESET - RESET Output goes low
whenever V
RESET will remain low for 200ms after V
crosses the reset threshold on power-up.
SP791EB/04
OUT
if not used.
OUT
CC
CC
falls to 150mV above the reset
falls below the reset threshold.
and GND, which sets it to
CC
OUT
is above the reset thresh-
to cause WDO to go to
SP791 Evaluation Board Manual
CC
3
Pin 16 - WDPO - Watchdog-Pulse Output.
Upon the absence of a transition at WDI,WDPO
will pulse low for 1ms. WDPO precedes WDO
by 70ns.
Note: To accurately measure the extremely small
supply current in Battery Back-up mode, you
need to cut split pads SP1 & SP2 (solder side of
board) severing connections to C1 & C2 which
would have leakage currents in the measurement
range. Also, remove charging circuit components
C
BATT
and D1 if they are installed.
©Copyright 2000 Sipex Corporation