SP691ACN SIPEX [Sipex Corporation], SP691ACN Datasheet - Page 11

• Manufacturer Part Number: SP691ACN
• Description: Low Power Microprocessor Supervisory with Battery Switch-Over
• Manufacturer: SIPEX [Sipex Corporation]

RESET and RESET Outputs
The SP691A/693A/800L/800M devices'
RESET and RESET outputs ensure that the µP
powers up in a known state, and prevents
code-execution errors during power-down or
brownout conditions.
The RESET output is active low, and typically
sinks 3.2mA at 0.1V saturation voltage in its
active state. When deasserted, RESET sources
1.6mA at typically V
is open drain, active high, and typically sinks
3.2mA with a saturation voltage of 0.1V. When
no backup battery is used, RESET output is
guaranteed to be valid down to V
an external 10kΩ pull-down resistor on RESET
ensures that RESET will be valid with V
down to GND as shown on Figure 18. As V
goes below 1V, the gate drive to the RESET
output switch reduces accordingly, increasing
the R
10kΩ pull-down resistor ensures the parallel
combination of switch plus resistor is around
Figure 19. Reset and Chip-Enable Timing
Date: 5/25/04
4) Watchdog function
5) Internal switch
where the watchdog output goes to a logic
LOW state if the watchdog input is not
toggled for greater than the timeout period.
to V
threshold.
DS
THRESHOLD
(ON) and the saturation voltage. The
BATT
RESET
RESET
CE
if the V
RESET
SP691A/693A/800L/800M Low Power Microprocessor Supervisor with Battery Switch-Over © Copyright 2004 Sipex Corporation
CE
Vcc
OUT
OUT
IN
CC
Switches over from V
– 0.5V. RESET output
falls below the reset
Monitors µP activity
CC
100µs
= 1V, and
12µ
CC
CC
CC
11
Figure 18. External Pull-down Resistor Ensures
RESET is Valid with V
10kΩ and the output saturation voltage is below
0.4V while sinking 40µA. When using a 10kΩ
external pull-down resistor, the high state for
the RESET output with Vcc = 4.75V is 4.5V
typical. For battery voltages less than or equal
to 2V connected to V
remains valid for V
RESET and RESET are asserted when V
below the reset threshold and remain asserted
for the Reset Timeout Period (200ms nominal)
after V
on power-up. Refer to Figure 19. The devices'
battery-switchover comparator does not affect
reset assertion. However, both reset outputs are
asserted in battery-backup mode since V
be below the reset threshold to enter this mode.
CC
100µs
rises above the reset threshold voltage
Corporation
RESET
CC
15
CC
BATT
Down to Ground.
from 0V to 5.5V.
, RESET and RESET
10kΩ
TO µP RESET
CC
CC
must
falls