IMP183 4/A/D
Application Information
Operation – Power Monitor
The IMP1834 supervisors simultaneously detect out-of-tolerance
power supply conditions on both 3.3V and 5V power supplies. If
the voltages at 5V
IN
or 3.3V
IN
are outside the tolerance band, the
reset for the failing supply voltage becomes active. When the moni-
tored 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 IMP1834 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
.
t
R
V
INTP
(Max)
V
INTP
(Min)
V
INTP
Reset Signal Polarity and Output Stage Structure
The IMP1834 and IMP1834A supervisors have active LOW reset
signals. The IMP1834D reset outputs are active HIGH.
The IMP1834 and IMP1834D have CMOS push-pull output
stages. The IMP1834A has open drain reset outputs.
IMP Part
IMP1834
IMP1834EMA
IMP1834S
IMP1834A
IMP1834AEMA
IMP1834AS
IMP1834D
IMP1834DEMA
IMP1834DS
RESET Polarity
LOW
LOW
LOW
LOW
LOW
LOW
HIGH
HIGH
HIGH
Output Stage
Configuration
Push-Pull
Push-Pull
Push-Pull
Open Drain
Open Drain
Open Drain
Push-Pull
Push-Pull
Push-Pull
Trip Point Tolerance Selection
The 3.3VTOL and 5VTOL inputs allow independent selection of
the reset trip points. If 5VTOL is connected to the 5V supply input,
a 10% tolerance is selected. If 5VTOL is grounded, a 5% tolerance
is selected.
RESET
V
OH
V
IN
t
RPU
If 3.3VTOL is connected to the 3.3V supply input, a 20% tolerance
is selected. If 3.3VTOL is grounded, a 10% tolerance is selected.
See
Table 1.
The 3.3VTOL and 5VTOL tolerance select inputs should be tied to
ground or to the respective input supply voltage pin, 3.3V
IN
or 5V
IN
.
V
OL
RESET
(IMP1834D Only)
1834_10.eps
Figure 1. Timing Diagram: Power Up
V
IN
t
F
V
INTP
(Max)
V
INTP
V
INTP
(Min)
> t
RPD
RESET
V
OH
V
OL
RESET
(IMP1834D Only)
RESET Slews
with V
CC
1834_09.eps
Figure 2. Timing Diagram: Power Down
4
408-432-9100/www.impweb.com
©
1999 IMP, Inc.
A1PROS [ A1 PROS CO., LTD. ]
