cat1232 Catalyst Semiconductor, cat1232 Datasheet - Page 5

• Manufacturer Part Number: cat1232
• Description: 5v And 3.3v Supply Monitor, Watchdog Timer, Manual Reset, With Active High & Low Resets
• Manufacturer: Catalyst Semiconductor

V
APPLICATION INFORMATION
SUPPLY VOLTAGE MONITOR
Reset Signal Polarity and Output Stage Structure
¯¯¯¯¯¯ is an active LOW signal. It is developed with
RESET
an open drain driver in the CAT1232LP. A pull-up
resistor is required, typical values are 10kŸ to 50kŸ.
The CAT1832 uses a CMOS push-pull output stage
for the RESET
RESET is an active High signal developed by a
CMOS push-pull output stage and is the logical
opposite to RESET
Trip Point Tolerance Selection
The TOL input is used to select the V
threshold. This selection is made connecting the
TOL input to ground or V
Ground makes the V
CAT1232LP and 2.88V for the CAT1832.
Connecting TOL to V
4.37V for the CAT1232LP and 2.55V for the
CAT1832.
After V
RESET and RESET
period of 250ms.
On power-down, once V
threshold the RESET outputs will remain active and
are guaranteed valid down to a V
Figure 1. Timing Diagram: Power Up
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CC
¯¯¯¯¯¯ .
CC
V
CCTP(MIN)
has risen above the trip point set by TOL,
¯¯¯¯¯¯ .
¯¯¯¯¯¯ remain active for a minimum time
V
CC
CC
CCTP
V
CCTP(MAX)
makes the V
t
R
trip threshold 4.62V for the
t
CC
RPU
CC
falls below the reset
. Connecting TOL to
CC
level of 1.0V.
CC
V
V
OH
OL
trip threshold
CC
RESET
RESET
trip point
5
Manual Reset Operation
Push-button input, PBRST
reset signals. The pushbutton input is debounced and
is pulled high through an internal 40kŸ resistor.
When PBRST
20ms, both resets become active and remain active
for a minimum time period of 250ms after PBRST
returns high.
No external pull-up resistor is required, since PBRST
is pulled high by an internal 40kŸ resistor.
¯¯¯¯¯¯ can be driven from a TTL or CMOS logic line
PBRST
or short-ed to ground with a mechanical switch.
Figure 2. Timing Diagram: Power Down
CAT1232LP
CAT1232LP
TOL = GND
TOL = GND
RESET
RESET
Tolerance
TOL = V
TOL = V
CAT1832
CAT1832
Voltage
Select
V
CC
¯¯¯¯¯¯ is held low for the minimum time of
V
CC
CC
CCTP(MAX)
V
Tolerance
Trip Point
CCTP
10 %
20 %
10 %
5 %
¯¯¯¯¯¯ , allows the user to issue
V
V
OH
OL
V
CCTP(MIN)
t
F
t
4.25
4.50
2.47
2.80
MIN
RPD
Trip Point Voltage (V)
CAT1232, CAT1832
NOMINAL
Doc. No. MD-3018 Rev. D
4.37
4.62
2.55
2.88
¯¯¯¯¯¯
MAX
4.49
4.74
2.64
2.97