IMP1834/A/D
Application Information
Operation – Power Monitor
Reset Signal Polarity and Output Stage Structure
The IMP1834 supervisors simultaneously detect out-of-tolerance The IMP1834 and IMP1834A supervisors have active LOW reset
power supply conditions on both 3.3V and 5V power supplies. If signals. The IMP1834D reset outputs are active HIGH.
the voltages at 5V or 3.3V are outside the tolerance band, the
IN
IN
The IMP1834 and IMP1834D have CMOS push-pull output
stages. The IMP1834A has open drain reset outputs.
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.
Output Stage
Configuration
IMP Part
RESET Polarity
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.
IMP1834
LOW
LOW
LOW
LOW
LOW
LOW
HIGH
HIGH
HIGH
Push-Pull
Push-Pull
Push-Pull
Open Drain
Open Drain
Open Drain
Push-Pull
Push-Pull
Push-Pull
IMP1834EMA
IMP1834S
IMP1834A
All supply current for the IMP1834 devices is drawn from the
IMP1834AEMA
IMP1834AS
IMP1834D
input (5VIN or 3.3V ) with the highest voltage level. The outputs
IN
draw current from their input supplies 5VIN and 3.3VIN
.
IMP1834DEMA
IMP1834DS
tR
V
INTP (Max)
Trip Point Tolerance Selection
V
INTP
VINTP (Min)
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.
VIN
tRPU
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.
RESET
RESET
VOH
The 3.3VTOL and 5VTOL tolerance select inputs should be tied to
ground or to the respective input supply voltage pin, 3.3VIN or 5VIN.
VOL
(IMP1834D Only)
1834_10.eps
Figure 1. Timing Diagram: Power Up
tF
VIN
VINTP (Max)
V
INTP
VINTP (Min)
> tRPD
RESET
RESET Slews
with VCC
VOH
VOL
RESET
1834_09.eps
(IMP1834D Only)
Figure 2. Timing Diagram: Power Down
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© 1999 IMP, Inc.
4
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