November 2006
rev 1.5
ASM1834/A/D
Detailed Description
Operation Power Monitor
The ASM1834 supervisors simultaneously detect out-of-
tolerance power supply conditions on both 3.3V and 5V
power supplies. If the voltages at 5VIN or 3.3VIN are outside
the tolerance band, the reset for the falling supply voltage
becomes active. When the monitored supply returns to an in-
tolerance state, the reset remains active for approximately
350ms before returning to the inactive state.
On power-up, the reset signals are kept active for
approximately 350ms after the power supply voltages have
reached the selected tolerance. This allows the power supply
and microprocessor to stabilize before the reset is removed.
All supply current for the ASM1834 devices is drawn from the
input (5V
IN
or 3.3V
IN
) with the highest voltage level. The
outputs draw current from their input supplies 5V
IN
and
3.3V
IN
.
RESET
V
OH
RESET
V
IN
V
INTP
(MAX)
V
INTP
V
INTP
(MIN)
t
F
t
RPD
RESET Slews
with V
CC
Figure 2: Timing Diagram: Power Down (ASM1834D only)
Reset Signal Polarity and Output Stage Structure
The ASM1834 and the ASM1834A supervisors have active
LOW reset signals. The ASM1834D reset outputs are active
HIGH.
The ASM1834 and the ASM1834D have CMOS push-pull
output stages. The ASM1834A has open drain reset outputs.
~
~~
RESET
Polarity
LOW
LOW
LOW
LOW
LOW
LOW
HIGH
HIGH
HIGH
V
OL
~~
t
R
V
INTP
(MAX)
V
INTP
t
RPU
RESET
V
OH
Part #
ASM1834
ASM1834U
ASM1834S
ASM1834A
V
OL
RESET
Output Stage
Configuration
Push-Pull
Push-Pull
Push-Pull
Open Drain
Open Drain
Open Drain
Push-Pull
Push-Pull
Push-Pull
V
INTP
(MIN)
~
~
V
IN
ASM1834AU
ASM1834AS
ASM1834D
ASM1834DU
ASM1834DS
Figure 1: Timing Diagram: Power Up (ASM1834D only)
~
~
~~
Dual 5V and 3.3V µP Power Supply Supervisor with Manual Reset
Notice: The information in this document is subject to change without notice
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PULSECORE [ PulseCore Semiconductor ]
