IMP183 4/A/D
P
OWER
M
ANAGEMENT
Dual 5V and 3.3V
µ
P Power
Supply Supervisors w/Manual Reset
– Push-Pull and Open-Dr ain Outputs
– Select able T r ip Point Toler ance
The IMP1834 supervisors simultaneously monitor both 3.3V and 5V
power sources and issue reset signals when either supply is out of toler-
ance. When an out-of-tolerance condition is detected, the output-reset
signal of the affected supply becomes active and resets the system micro-
processor/microcontroller. On power-up and after the supply voltage
returns to an in-tolerance condition, the reset signal remains active for
approximately 350ms. This allows the power supply and system micro-
processor to stabilize.
The IMP1834 supervisors are pin-compatible with devices from Dallas
Semiconductor and require up to 40% less current.
Tolerance levels are independently selectable for both supplies.
Tolerance options are 5- and 10-percent for the 5V supply and for the
3.3V supply, 10- and 20-percent.
The IMP1834 and IMP1834D have push-pull reset output stages. The
IMP1834A active LOW reset outputs are open drain devices that can
both be connected to either 5 volt or 3.3 volt supply. The IMP1834 and
IMP1834A have active LOW reset outputs. The IMP1834D has active
HIGH reset outputs.
All devices can issue reset signals through an internally debounced
pushbutton reset input that affects both reset outputs.
All devices operate over the extended industrial temperature range.
Devices are available in 8-pin DIP, surface mount 8-pin SO and 8-pin
MicroSO packages. Die are also available.
Key Features
x
Lower power, pin-compatible replacements for
the Dallas DS1834
— 40% lower maximum supply current:
30µA vs 50µA
x
Monitor 5V and 3.3V supplies simultaneously
x
5V and 3.3V power-on reset
x
350ms reset time
x
Debounced pushbutton reset input
x
Push-Pull CMOS output
— IMP1834, IMP1834D
— Eliminates external pull-up resistors
— Active LOW (IMP1834), HIGH (IMP1834D)
x
Open drain output
— IMP1834A
— Active LOW
x
Selectable 5V and 3.3V trip point tolerance
x
Internal power drawn from highest input
voltage, 5V or 3.3V
x
Precision temperature-compensated voltage
reference and comparator
x
Low-cost surface mount SO, compact
MicroSO and DIP packages
x
Wide operating temperature, – 40°C to +85°C
IMP1834A
2
5VRESET
Block Diagram
IMP1834
5V
IN
1
1834_02.eps
7
3.3VRESET
5VTOL
3
5V Tolerance
Bias
Low TC
Reference
40kΩ
+
–
For IMP1834D
350 ms
Delay
2
5VRESET
5VRESET (IMP1834D)
PBRST
3.3V
IN
3.3VTOL
GND
5
8
6
4
3.3V Tolerance
Bias
Pushbutton Level
Sense and Debounce
For IMP1834D
+
–
350 ms
Delay
7
3.3VRESET
3.3VRESET (IMP1834D)
1834_01.eps
©
1999 IMP, Inc.
408-432-9100/www.impweb.com
1
A1PROS [ A1 PROS CO., LTD. ]
