PIN DESCRIPTION
SP705/706
SP707/708
SP813L
NAME
FUNCTION
DIP/
DIP/
SOIC
DIP/
SOIC
µSOIC
SOIC
µSOIC
µSOIC
Manual Reset - This input triggers a reset pulse
when pulled below 0.8V. This active-LOW input
has an internal 250µA pull-up current. It can be
driven from a TTL or CMOS logic line or shorted
to ground with a switch
MR
1
3
1
3
1
3
VCC
+5V power supply
2
3
4
5
2
3
4
5
2
3
4
5
GND
Ground reference for all signals
Power-Fail Input - When this voltage monitor input
is less than 1.25V, PFO goes LOW. Connect PFI
to ground or VCC when not in use.
PFI
4
5
6
7
4
5
6
7
4
5
6
7
Power-Fail Output - This output is HIGH until PFI
is less than 1.25V.
PFO
Watchdog Input - If this input remains HIGH or
LOW for 1.6s, the internal watchdog timer times
out and WDO goes LOW. Floating WDI or
connecting WDI to a high-impedance tri-state
buffer disables the watchdog feature. The internal
watchdog timer clears whenever RESET is
asserted, WDI is tri-stated, or whenever WDI sees
a rising or falling edge.
WDI
N.C.
6
-
8
-
-
-
6
-
8
-
No Connect.
6
7
8
1
Active-LOW RESET Output - This output pulses
LOW for 200ms when triggered and stays LOW
whenever VCC is below the reset threshold (4.65V
for the SP705/707/813L and 4.40V for the
SP706/708). It remains LOW for 200ms after Vcc
rises above the reset threshold or MR goes from
LOW to HIGH. A watchdog timeout will not trigger
RESET unless WDO is connected to MR.
RESET
7
1
-
-
Watchdog Output - This output pulls LOW when
the internal watchdog timer finishes its 1.6s count
and does not go HIGH again until the watchdog is
cleared. WDO also goes LOW during low-line
conditions. Whenever VCC is below the reset
threshold, WDO stays LOW. However, unlike
RESET, WDO does not have a minimum pulse
width. As soon as VCC is above the reset
WDO
8
2
-
-
8
7
2
1
threshold, WDO goes HIGH with no delay.
Active-HIGH RESET Output - This output is the
complement of RESET. Whenever RESET is
HIGH, RESET is LOW, and vice versa. Note the
SP813L/813M has a reset output only.
RESET
-
-
8
2
Table 1. Device Pin Description
June 2008 Rev C
SP705 Low Power Microprocessor Supervisory Circuits
© 2008 Exar Corporation
4
EXAR [ EXAR CORPORATION ]
