Micrel
MIC2772
Transients on VCC
The MIC2772 is inherently immune to very short
“glitches” on VCC.
In the case of very brief
transients, VCC may drop below the reset-voltage
threshold without triggering a reset. As shown in the
graph, the MIC2772 is relatively immune to
transients with typical duration of 25us. The lines on
the graph represent the typical allowable transient
duration for a given amount of threshold overdrive
that will not generate a reset. The data was taken by
adding negative-going square-wave pulse to a DC
input voltage set at 0.5V above actual measured
threshold for the part being characterized. Figure 1
shows the graph for the MIC2772[UP3] and Figure 2
shows the graph for the MIC2772[UP5]
35
30
25
20
15
10
5
0
V
TH
= 4.393V
Motorola 68HC11 family is one example. Because
the MIC2772’s output is active-low, open-drain, it
can be connected directly to the processor’s reset
pin with only the pull-up resistor normally required.
MIC2772 Replaces Single Supervisor
The table below lists common single voltage
supervisors that can be considered for replacement
by MIC2772.
P/N Suffix
L2L3
Supervisor #1
MIC6315-46D2
Supervisor #2
MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
MIC6315-31D3,
MIC809T, MIC811T
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
MIC6315-31D3,
MIC809T, MIC811T
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
MIC6315-31D3,
MIC809T, MIC811T
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
Typical Transient
Response
M2M3
MIC6315-44D2
MAX. TRANSIENT DURATION (µs)
L3L3
MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
MIC6315-31D3,
MIC809T, MIC811T
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
MIC6315-31D2
MIC6315-29D2
M3M3
0
200 400 600 800 1000
RESET COMP. OVERDRIVE V
TH
- V
CC
(mV)
T3T3
S3S3
Figure 1
40
35
30
25
20
15
10
5
0
V
TH
= 2.933V
Typical Transient
Response
MAX. TRANSIENT DURATION (µs)
T2T3
S2S3
L3T3
0
200 400 600 800 1000
RESET COMP. OVERDRIVE V
TH
- V
CC
(mV)
MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
M3S3
Figure 2
Interfacing to Processors with Bi-directional
Reset Pins
Some microprocessors have reset signal pins that
are bi-directional, rather than input only. The
April 2005
7
M9999-042605
(408) 955-1690
MICREL [ MICREL SEMICONDUCTOR ]
