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]
0
5
10
15
20
25
30
35
0 200 400 600 800 1000
MAX. TRANSIENT DURATION (µs)
RESET COMP. OVERDRIVE V
TH
- V
CC
(mV)
Typical Transient
Response
V
TH
= 4.393V
Figure 1
0
5
10
15
20
25
30
35
40
0 200 400 600 800 1000
MAX. TRANSIENT DURATION (µs)
RESET COMP. OVERDRIVE V
TH
- V
CC
(mV)
Typical Transient
Response
V
TH
= 2.933V
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
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 Supervisor #1 Supervisor #2
L2L3 MIC6315-46D2 MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
M2M3 MIC6315-44D2 MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
L3L3 MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
M3M3 MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
T3T3 MIC6315-31D3,
MIC809T, MIC811T
MIC6315-31D3,
MIC809T, MIC811T
S3S3 MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
T2T3 MIC6315-31D2 MIC6315-31D3,
MIC809T, MIC811T
S2S3 MIC6315-29D2 MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
L3T3 MIC1810-5,
MIC6315-46D3,
MIC809L, MIC811L
MIC6315-31D3,
MIC809T, MIC811T
M3S3 MIC1810-10,
MIC6315-44D3,
MIC809M,
MIC811M
MIC1815-10,
MIC6315-29D3,
MIC809S, MIC811S
April 2005 7
M9999-042605
(408) 955-1690
